tag:theconversation.com,2011:/es/topics/fish-187/articlesFish – The Conversation2024-03-27T01:14:51Ztag:theconversation.com,2011:article/2265132024-03-27T01:14:51Z2024-03-27T01:14:51ZThese extraordinary Australian islands are teeming with life – and we must protect them before it’s too late<p>In the Southern Ocean about 4,000 kilometres from Perth lies a truly extraordinary place. Known as the Heard Island and McDonald islands, they are among the most remote places on Earth: a haven for marine life amid the vast ocean, virtually undisturbed by human pressures.</p>
<p>But as our <a href="https://research-repository.uwa.edu.au/en/publications/understanding-the-marine-ecosystems-surrounding-heard-island-and-">report</a> released today reveals, this special place in Australia’s territory is at risk. In particular, climate change is warming the waters around the islands, threatening a host of marine life.</p>
<p>More than 20 years ago, a marine reserve was declared over the islands and parts of the surrounding waters. At the time, it was a significant step forward in environmental protection. But since then, science has progressed and the threats have worsened. </p>
<p>Our report reviewed these protections and found they are no longer adequate. The marine reserve surrounding the Heard and McDonald islands must urgently be expanded. </p>
<h2>Spotlight on the reserve system</h2>
<p>The Heard and McDonald islands are just a tiny tip of the Kerguelen Plateau – a huge underwater mass rising high above the surrounding ocean basins. </p>
<p>The plateau intercepts the Antarctic Circumpolar Current, the strongest current system in the world. When the current hits the plateau, deep, nutrient-rich waters are pushed to the surface. This supports a food chain ranging from tiny plankton to fish, invertebrates, seabirds and marine mammals such as elephant seals and sperm whales.</p>
<p>On Heard Island, Mawson’s Peak is officially Australia’s highest mountain. It is 2,745 metres high and forms the summit of an active volcano known as Big Ben. Heard Island and McDonald Islands also host valuable fisheries for Patagonian toothfish and mackerel icefish.</p>
<p>The marine reserve around the islands was declared in 2002 and extended in 2014. It now covers 17% of what is known as the “exclusive economic zone” – the area of the sea in which a nation (in this case, Australia) has exclusive rights to resources such as fish and minerals.</p>
<p>The original reserve was primarily designed for waters shallower than 1,000m, because in 2002 little was known about the area’s deeper waters. A review of the reserve system is due this year.</p>
<p>Our report draws on more than 20 years’ of research conducted since the reserve was first declared. It highlights new scientific understanding of the region and the need to expand its protection.</p>
<p><iframe id="oSiut" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/oSiut/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>Climate pressures on the plateau</h2>
<p>Climate change poses wicked threats for the Heard and McDonald islands and surrounding marine environment. </p>
<p>We found the shelf area is <a href="https://www.nature.com/articles/s41467-020-20781-1">becoming warmer</a>. This potentially threatens species adapted to cold polar waters, such as the mackerel icefish. This species lives in shallow water and is an important food source for fur seals and other predators. </p>
<p>No other sub-antarctic shelf exists to the south of Heard Island, which means the region is a vital animal habitat. Maintaining the islands’ biodiversity in the face of climate change is best achieved by extending the existing marine reserve to cover more shallow waters, as well as protecting currently unprotected deeper waters.</p>
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Read more:
<a href="https://theconversation.com/australias-only-active-volcanoes-and-a-very-expensive-fish-the-secrets-of-the-kerguelen-plateau-123351">Australia's only active volcanoes and a very expensive fish: the secrets of the Kerguelen Plateau</a>
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<h2>Protecting deep-water species</h2>
<p>The Patagonian toothfish is a top predator species that connects different parts of the food web. Commercial fishing in the islands’ economic zone targets toothfish using “<a href="https://www.fisheries.noaa.gov/national/bycatch/fishing-gear-bottom-longlines">bottom longlines</a>” which are weighted to the seafloor at depths down to 2,000m. The footprint of fishing operations has expanded over the past 30 years.</p>
<p>Our report suggests protecting <a href="https://www.sciencedirect.com/science/article/pii/S0304380016303325">spawning grounds</a> of toothfish will reduce risks to this species and help ensure the fishery does not deplete fish stock.</p>
<p>Fishing is managed in such a way to eliminate the accidental catching (or by-catch) of seabirds. But there is still significant by-catch of a number of non-target fish species, especially skates. </p>
<p>Keeping fishing out of some areas can reduce pressure on vulnerable species. Important areas for achieving this are in the deeper waters to the southeast of Heard Island. </p>
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Read more:
<a href="https://theconversation.com/climate-risk-index-shows-threats-to-90-per-cent-of-the-worlds-marine-species-190221">Climate risk index shows threats to 90 per cent of the world's marine species</a>
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<h2>Sustaining biodiversity into the future</h2>
<p>Our analysis reveals an updated understanding of the marine ecosystems surrounding Heard and McDonald islands.</p>
<p>Scientists now know more about where <a href="https://www.sciencedirect.com/science/article/abs/pii/S1470160X16302977">marine mammals and birds forage</a> – particularly in the important period when parents are feeding their young. We found some species that breed on Heard Island, including king penguins and fur seals, rely on areas not protected by the marine reserve during these times.</p>
<p>Our analysis also reveals a complex mosaic of productive habitats in shallow water, and less productive habitats in deeper water. This in turn affects the distribution of animal species.</p>
<p>Increased protection for the areas in the west, south, and southeast of the economic zone will be needed to protect animals in these habitats.</p>
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<img alt="Increased protections are needed to protect biodiversity in the region." src="https://images.theconversation.com/files/298059/original/file-20191022-28092-12ocbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298059/original/file-20191022-28092-12ocbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298059/original/file-20191022-28092-12ocbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298059/original/file-20191022-28092-12ocbi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298059/original/file-20191022-28092-12ocbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298059/original/file-20191022-28092-12ocbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298059/original/file-20191022-28092-12ocbi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Bird activity behind a research vessel near the Kerguelen Plateau.</span>
<span class="attribution"><span class="source">Paul Tixier</span></span>
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<h2>Looking ahead</h2>
<p>The current marine reserve covering Heard and McDonald islands is not sufficient. It should cover deeper water ecosystems and provide protection for foraging areas of resident seals, penguins and albatross. </p>
<p>Protecting spawning grounds of toothfish and areas important to cold-adapted species, such as mackerel icefish, will help ensure these species have the best chance against continuing warming of the ocean. </p>
<p>Extending the protections would help Australia meet its domestic policy and international agreements. For example, the federal government has committed to protecting <a href="https://theconversation.com/weve-committed-to-protect-30-of-australias-land-by-2030-heres-how-we-could-actually-do-it-217795">at least 30%</a> of ocean ecosystems by 2030.</p>
<p>It would also ensure our marine protected areas are <a href="https://www.dcceew.gov.au/environment/marinereservesreview/resources/representative-system">nationally representative</a> – a key national objective Australia has committed to.</p>
<p>By extending adequate protection of Heard and McDonald islands, Australia has the chance to show global leadership in conserving this precious natural asset in the Southern Ocean.</p><img src="https://counter.theconversation.com/content/226513/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The report underpinning this article was part-funded by Pew Charitable Trusts and the Australian Marine Conservation Society.</span></em></p>A new report has found the marine reserve covering the Heard and McDonald islands must urgently be expanded.Ian Cresswell, Adjunct professor, The University of Western AustraliaAndrew J Constable, Adviser, Antarctica and Marine Systems, Science & Policy, University of TasmaniaKeith Reid, Honorary Research Associate, Institute for Marine and Antarctic Studies, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2246822024-03-20T22:41:06Z2024-03-20T22:41:06ZHow do halibut migrate? Clues are in their ear bones<figure><img src="https://images.theconversation.com/files/578657/original/file-20240220-18-5yndy5.jpg?ixlib=rb-1.1.0&rect=24%2C18%2C3953%2C2999&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The habitats used throughout the halibut's life and the movements between them are difficult to characterize.</span> <span class="attribution"><span class="source">(Charlotte Gauthier)</span>, <span class="license">Fourni par l'auteur</span></span></figcaption></figure><p>Rising temperatures, changes in major currents, <a href="https://theconversation.com/why-the-st-lawrence-estuary-is-running-out-of-breath-184626">oxygen depletion at great depths</a>: the Gulf of St. Lawrence has undergone major changes in its environmental conditions in recent decades. That has put many species in danger and, as a consequence, made them more sensitive to the effects of fishing.</p>
<p>However, these changes are benefiting other species such as Atlantic halibut, which is beating records for its abundance and is presently seeing the highest stock in the Gulf of St. Lawrence in <a href="https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/41206708.pdf">the last 60 years</a>.</p>
<p>As a biology researcher, I’d like to shed some light on some of the mysteries that still surround this unusual species.</p>
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<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
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<h2>Atlantic halibut: champion of the Gulf of St. Lawrence</h2>
<p>Atlantic halibut is a flatfish that lives at the bottom of the estuary and gulf of the St. Lawrence. It is prized for its fine, firm white flesh, which is highly appreciated by consumers.</p>
<p>Halibut can grow to impressive sizes of <a href="https://www.tandfonline.com/doi/full/10.1080/23308249.2021.1948502">more than two metres</a>. Because of the quality of its flesh and its popularity on dinner plates, it is currently the most commercially valuable fish in the Gulf of St. Lawrence.</p>
<p>But this has not always been the case. In the 1950s, the adult, harvestable portion of halibut populations, known as the stock, <a href="https://academic.oup.com/icesjms/article/73/4/1104/2458915?login=false">suffered a major decline due to overfishing</a>.</p>
<p>If we want to continue to exploit this resource over the long term, we must not repeat the same mistakes we made in the past. To avoid these mistakes, it is vital to have a good understanding of the life cycle of halibut and the effects that fishing can have on the stock. So far, this has not been done to the fullest.</p>
<h2>The challenges for sustainable fishing</h2>
<p>The basic biology of Atlantic halibut is fairly well known. However, both the habitats they use throughout their lives and their movement between these places are more difficult to characterize.</p>
<p><a href="https://academic.oup.com/icesjms/article/77/7-8/2890/5923787?login=false">Recent studies</a> have placed satellite tags on halibut to record data on the depth and temperature of the water in which they are found, making it possible to accurately calculate their movement. By using this method, the researchers were able to identify the trajectories of adult halibut over a one-year period and discover that they reproduce in winter in the deep channels of the Gulf.</p>
<p>In the halibut’s different annual trajectories, the researchers observed that, in summer, some remain in the deep channels while others migrate to shallower areas.</p>
<p>Even with this new information, a number of questions remain, specifically about the youngest life stages, which are caught only anecdotally in the Gulf. Satellite tags also provide accurate information, but only over a one-year period, which doesn’t tell the whole story for a fish that can live up to 50 years.</p>
<p>With this in mind, the use of a new tool to study the entire life of fish becomes highly relevant.</p>
<h2>Ear bones to the rescue</h2>
<p>All bony fish have small calcareous structures in their inner ear called otoliths, or ear bones, which perform balance and hearing functions.</p>
<p>Otoliths develop at the very beginning of a fish’s life and grow at the same rate as the fish. Otoliths form annual growth rings that are comparable to those visible in tree trunks.</p>
<p>To grow, otoliths accumulate chemical elements that are found in the environment in which the fish swim. So, when the fish moves, the chemical elements accumulated in the otoliths will be different from one place to another. Each location is characterized by a unique combination of different concentrations of chemical elements. This is known as an elemental fingerprint. Identifying these fingerprints can provide us with crucial information about the movement of fish in different places throughout their lives.</p>
<p>I used this method of characterizing the chemical elements in otoliths to study the migratory patterns of Atlantic halibut in the Gulf of St. Lawrence.</p>
<h2>A wide range of migratory strategies</h2>
<p>To find out what concentrations of a chemical element correspond to the place where the fish was caught, we use the fingerprint of the otolith margin, i.e. the material at the end of the outermost ring of the otolith, which was accumulated last.</p>
<p>The concentrations of the elements found there are considered to be characteristic of the place where the fish was caught. By analyzing the margins of nearly 200 halibut otoliths from all over the Gulf, I was able to distinguish two basic fingerprints: one representative of surface waters (less than 100 metres deep) and one characteristic of deeper waters (more than 100 metres deep).</p>
<p>Once these fingerprints had been identified, I observed the concentration of chemical elements throughout the life of the fish so that I could associate each moment of life with either the surface water fingerprint or the deep-water fingerprint.</p>
<p>By separating the life of each individual into time spent in surface and deep waters, I was able to identify recurring patterns and group them into three different migratory strategies: residents, annual migrants and irregular migrants.</p>
<p>In this way, I was able to observe that halibut caught in the southern part of the Gulf were mainly annual migrants, and therefore undertake migrations between deep and shallow waters every year. However, in the northern part of the Gulf the majority are residents. Residents are fish that may have migrated early in their lives, but have settled permanently in deep waters before reaching maturity. Irregular migrants, on the other hand, show migrations on a more sporadic frequency, and are found in similar proportions throughout the study area.</p>
<h2>On the right track to optimal management</h2>
<p>My study is the first to offer a global view of the movements made by halibut over their entire lifetime.</p>
<p>This new information provides a better understanding of the structure of the stock and the diversity of migratory strategies that can be found within it.</p>
<p>Given that these strategies are distributed differently in different areas of the Gulf, we can ensure that we do not disproportionately target halibut using the same migratory strategy and avoid overfishing a single component of the stock.</p>
<p>In this way, it is possible to conserve this diversity, which helps the stock’s resilience in the face of the various changes that can occur.</p><img src="https://counter.theconversation.com/content/224682/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charlotte Gauthier has received funding from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Fondation de l'Université du Québec à Chicoutimi.
</span></em></p>Atlantic halibut are making a strong comeback in the Gulf of St. Lawrence. But how do we know where the fish move throughout their lives?Charlotte Gauthier, Étudiante au doctorat, Université du Québec à Chicoutimi (UQAC)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2189772024-02-15T22:07:25Z2024-02-15T22:07:25Z8 ways that stopping overfishing will promote biodiversity and help address climate change<figure><img src="https://images.theconversation.com/files/576010/original/file-20240215-18-gqysb.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3804%2C2545&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Schools of jackfish pictured in the ocean off Losin, Thailand. Overfishing is a contributing factor in global climate change.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Amid the escalating threats of a warming world, and with the latest annual United Nations global climate conference (COP28) behind us, there is one critical message that’s often left out of the climate change discourse. Halting overfishing is itself effective climate action.</p>
<p>This argument is the logical conclusion of a plethora of studies that unequivocally assert that stopping overfishing isn’t just a necessity, it’s a win-win for ocean vitality, climate robustness and the livelihoods reliant on sustainable fisheries.</p>
<p>The intricate relationship between climate change and ocean ecosystems was the subject of recent collaborative research — led by researchers at the University of British Columbia — that highlighted the crucial links between overfishing and climate change. </p>
<h2>Finding the connections</h2>
<p>Our collaborative team of international researchers applied a host of methodologies ranging from literature reviews to quantitative and quality analysis. The findings of <a href="https://doi.org/10.3389/fmars.2023.1250449">this research</a> illuminate eight key multifaceted impacts.</p>
<p>1 — Ending overfishing <a href="https://doi.org/10.3389/fmars.2020.00523">isn’t merely an ecological imperative but a vital climate action</a>. Doing so would bolster marine life resilience in the face of climate shifts and reduce associate carbon emissions.</p>
<p>2 — Large subsidized fishing boat fleets can <a href="https://doi.org/10.1126/science.abm1680">actually be a burden on small-scale fisheries, leaving them disproportionately vulnerable to shocks</a>. In turn, overfishing not only depletes resources but also escalates carbon emissions, <a href="https://doi.org/10.3389/fmars.2022.768784">intensifying climate impacts on these fisheries and their communities, particularly women</a>.</p>
<p>Additionally, the <a href="https://doi.org/10.3389/fmars.2022.802762">vulnerability of shellfish fisheries to climate stressors further underscores the importance of adaptive strategies</a> tailored to local conditions. </p>
<p>3 — Success stories, like the recovery of European hake stocks, <a href="https://doi.org/10.3389/fmars.2022.788339">reveal a direct tie between stock recuperation and reduced emissions intensity from fisheries</a>. <a href="https://theconversation.com/how-to-stay-hopeful-in-a-world-seemingly-beyond-saving-210415">We must champion and also learn from these successes</a>.</p>
<p>4 — Ecosystem-based fisheries management reverses the “order of priorities so that management starts with ecosystem considerations rather than the maximum exploitation of several target species.” </p>
<p>Ecosystem-based fisheries management has considerable potential to enhance sustainable catches while fostering carbon sequestration. This is perhaps <a href="https://doi.org/10.3389/fmars.2022.879998">best exemplified by the successful implimentation of ecosystem-based fisheries management in the western Baltic Sea</a>.</p>
<p>5 — <a href="https://doi.org/10.3389/fmars.2021.770805">Heavy metal pollution in the ocean — such as mercury or lead waste — intensifies the negative impacts of warming and overfishing</a>. This pollution reinforces the need for developing multifaceted regulations based around ecosystem and ocean sustainability solutions. </p>
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Read more:
<a href="https://theconversation.com/flipping-indigenous-regional-development-in-newfoundland-upside-down-lessons-from-australia-218298">Flipping Indigenous regional development in Newfoundland upside-down: lessons from Australia</a>
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<p>6 — Overfishing <a href="https://doi.org/10.3389/fmars.2021.597385">exacerbates climate and biodiversity threats</a>. Climate change contributes to less defined and predictable seasons <a href="https://theconversation.com/how-climate-change-induced-stress-is-altering-fish-hormones-with-huge-repercussions-for-reproduction-213140">and is causing reproductive challenges</a> and the <a href="https://theconversation.com/climate-change-is-further-reducing-fish-stocks-with-worrisome-implications-for-global-food-supplies-217428">propagation of diseases in fish populations</a> — among other issues.</p>
<p>Adding to these problems, <a href="https://doi.org/10.1016/j.tree.2007.07.001">overfishing itself is altering ecological dynamics, modifying habitats and opening new pathways for invasive species</a>. These compounding crises further exacerbate the impacts of overfishing on marine ecosystems while at the same time making fish populations more vulnerable to climate change.</p>
<p>The above factors all combine to reduce the catch potential in any given ecosystem. In turn, fishers are forced to venture farther and deeper in the ocean to fish — increasing carbon emissions, personal risk factors to fishers and <a href="https://www.greenmatters.com/p/what-is-bycatch">bycatch</a> concerns. </p>
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<img alt="A dead shark is seen tangled in a fishing net." src="https://images.theconversation.com/files/576013/original/file-20240215-24-d1h82g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576013/original/file-20240215-24-d1h82g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=386&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576013/original/file-20240215-24-d1h82g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=386&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576013/original/file-20240215-24-d1h82g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=386&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576013/original/file-20240215-24-d1h82g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=485&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576013/original/file-20240215-24-d1h82g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=485&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576013/original/file-20240215-24-d1h82g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=485&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Reduced fish catches can lead to fishers going farther, and deeper, out to sea to find fish — with a host of associated consequences.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>7 — International fisheries management must play a central role in promoting biodiversity and retaining the ocean’s carbon sequestration potential. While 87 nations have signed the UN’s <a href="https://doi.org/10.3389/fmars.2022.764609">Biodiversity of Areas Beyond National Jurisdiction Treaty</a> (also known as the High Seas Treaty), only one has ratified it. This treaty must be fully ratified and its effective implementation should be contingent upon the creation of marine protected areas that cover at least 30 per cent of the high seas.</p>
<p>8 — The ocean has huge carbon sequestration potential. <a href="https://doi.org/10.3389/fmars.2022.800972">Shifting from the generally accepted maximum of sustainable yield management to maximizing carbon sequestration in fisheries management could further advance climate goals</a>.</p>
<p>Future regulations should allocate a percentage of the annual fish quota to maintain the carbon sequestration function of marine animals. Simply put, beyond just being food, fish stocks serve vital carbon sequestration and biodiversity services that directly benefit humanity. Future regulations should reflect this reality.</p>
<h2>A simple goal</h2>
<p>This joint collaborative research underscores the urgency of this issue. Ending overfishing isn’t just an ecological imperative but a linchpin for climate action. Furthermore, fisheries aren’t mere victims in these dynamics, but have real agency to play a pivotal role in either exacerbating or mitigating climate change.</p>
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Read more:
<a href="https://theconversation.com/the-future-of-fishing-and-fish-and-the-health-of-the-ocean-hinges-on-economics-and-the-idea-of-infinity-fish-182749">The future of fishing and fish — and the health of the ocean — hinges on economics and the idea of 'infinity fish'</a>
</strong>
</em>
</p>
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<p>An ideal governance framework would focus on managing ecosystems with considerations for their diverse benefits, based on the best evidence available. Regulation of fisheries, while controversial, is essential to not overly exploit such a valuable public resource.</p>
<p>As we gear up to the next COP, we would do well to remember these conclusions. Without nurturing ocean life, addressing climate change becomes an uphill battle. Sustainable fisheries management is not just an ecological necessity. It is also the cornerstone of a resilient, sustainable future.</p><img src="https://counter.theconversation.com/content/218977/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rashid Sumaila receives funding from the Social Sciences and Humanities Research Council and the non-governmental organization Our Fish.</span></em></p>Recent research shows how reducing overfishing is both an ecological imperative and a critical means to addressing climate change.Rashid Sumaila, Director & Professor, Fisheries Economics Research Unit, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2226692024-02-12T13:58:41Z2024-02-12T13:58:41ZHow to buy sustainable salmon: an expert guide to navigating the nuance of eco-labels<figure><img src="https://images.theconversation.com/files/574194/original/file-20240207-28-t5ap9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Choosing between wild-caught and farmed salmon can be confusing to shoppers, but certain eco-labels can provide guidance. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fresh-fish-fillet-put-sale-supermarket-1958154268">monticello/Shutterstock</a></span></figcaption></figure><p>We’ve all been there. You’re in the supermarket freezer aisle trying to make sense of the different labels on seafood products. You know the oceans are <a href="https://www.fao.org/documents/card/en?details=cc0461en">in trouble</a> and you’re trying to do the right thing, but the information is confusing and seemingly contradictory. </p>
<p>One packet of salmon fillets has a smiling dolphin logo on the back. Another, a less-smiley bright blue fish logo. You pull out your smartphone and open the sustainable seafood app your friend told you about, only to become more confused by its traffic light ratings. In the end, you just pick any product that the label assures you is sustainable.</p>
<h2>Making sense of salmon sustainability</h2>
<p>Salmon is one of the <a href="https://www.fao.org/documents/card/en?details=cc0461en">most consumed</a> seafoods globally. It’s a rich source of <a href="https://fdc.nal.usda.gov/fdc-app.html#/food-details/173686/nutrients">protein, key micronutrients and fatty acids</a>. But with so many different products on the shelf, it’s hard to know which ones harm the environment and fish stocks the most. </p>
<p>Both wild-caught and farmed salmon can be sustainable, but determining the environmental impact of a fillet isn’t simple. Both can present significant social and environmental problems. Wild-caught salmon can be <a href="https://afspubs.onlinelibrary.wiley.com/doi/full/10.1002/fsh.10062">overfished</a> or sourced from vulnerable fish populations. But while salmon aquaculture can reduce the pressure on wild stocks, it’s no panacea. </p>
<p>Farmed salmon producers often <a href="https://academic.oup.com/icesjms/article/72/3/997/686282">face scrutiny</a> for overcrowding, parasites and pollution, with <a href="https://www.theguardian.com/environment/2023/sep/30/thousands-of-salmon-escaped-an-icelandic-fish-farm-the-impact-could-be-deadly">escapees from open-net pens</a> feared to endanger local wild populations. The fish meal used to feed farmed salmon presents further problems, as it often <a href="https://journals.plos.org/sustainabilitytransformation/article?id=10.1371/journal.pstr.0000005">originates from wild-caught fish</a> that aren’t always <a href="https://www.nature.com/articles/s41893-018-0077-1">taken at sustainable levels</a>.</p>
<p>These challenges are expected to be <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/eva.12164">exacerbated by shifting climates</a>: higher water temperatures and reduced rainfall can enable the growth of pathogens, and <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3624">increase the susceptibility of fish</a> populations to disease. </p>
<p><a href="https://gupea.ub.gu.se/bitstream/handle/2077/66214/gupea_2077_66214_4.pdf?sequence=4&isAllowed=y">Many</a> certification schemes, eco-labels, rankings and guides exist to signpost salmon sustainability. For wild-caught salmon, the <a href="https://www.msc.org/uk">Marine Stewardship Council</a> provides the gold standard, assuring that it has been sourced from fisheries managed according to rigorous environmental standards. For farmed salmon, a tick of approval from the <a href="https://asc-aqua.org/">Aquaculture Stewardship Council</a> is considered the most thorough certification, indicating responsible aquaculture practices.</p>
<p>One of us (Laurence Wainwright) has <a href="https://gupea.ub.gu.se/bitstream/handle/2077/66214/gupea_2077_66214_4.pdf?sequence=4&isAllowed=y">researched eco-labels for five years</a>, finding that these two certification schemes are currently the most scientifically sound, evidenced-based standards for seafood sustainability – including salmon. </p>
<p>Other seafood sustainability schemes offer some assurances of sustainability, but are often not nearly as rigorous. Schemes for farmed salmon such as the <a href="https://www.soilassociation.org/certification/aquaculture/">Soil Association’s organic standard</a> have recently <a href="https://www.theguardian.com/environment/2024/jan/30/unacceptable-greenwashing-scottish-farmed-salmon-should-not-be-labelled-organic-say-charities">faced criticism</a> for having standards that are perceived by some as not going far enough – or potentially even misleading customers by certifying some Scottish salmon farms as organic. </p>
<p>To a consumer, an “organic” label generally signifies that a product has been grown from organic feed and produced without the use of chemical pesticides or antibiotics. Farmed salmon can be organic, if raised and fed correctly. </p>
<p>A <a href="https://8point9.com/soil-association-pushes-back-against-criticism-of-organic-salmon/">Soil Association spokesperson</a> stated: “Organic farms must follow strict rules to minimise impacts on the environment and animal welfare, and when problems occur, they must prove they are taking action in order to use the organic logo.” The Soil Association’s aquaculture standards are currently under review following a <a href="https://www.soilassociation.org/our-standards/aquaculture-and-northern-ireland-organic-standards-consultation/consultation-on-soil-association-standards-for-uk-organic-aquaculture/">60-day consultation</a>, and an update to its standards is due later in 2024. </p>
<p>According to fish conservation charity <a href="https://wildfish.org/wp-content/uploads/2023/09/Responsibly-Sourced_-FINAL-REPORT_130923.pdf">WildFish</a>, some badges of sustainability in salmon aquaculture can mask details of unregulated salmon supply chains – with certifications rarely being lost even when conditions are breached. According to its 2023 report, some UK farms have been permitted to use wild-caught fish for feed and to use <a href="https://wildfish.org/wp-content/uploads/2023/09/Responsibly-Sourced_-FINAL-REPORT_130923.pdf">toxic chemicals</a> for parasite control, without losing their organic certification. This is controversial: such ambiguity and lack of transparency only hinders the salmon aquaculture industry. </p>
<p>In terms of wild-caught salmon, it is our strong opinion that it is never legitimate, under any circumstances, to call it organic. Not only is this misleading but it defies scientific evidence and undermines the meaning of the term organic.</p>
<h2>Which salmon should you buy?</h2>
<p>When buying salmon or ordering it at a restaurant, look for key information on the labels or ask staff about the sourcing of their fish. </p>
<ul>
<li><p>How, and from where, was it caught or farmed? Either can be sustainable, but the devil is in the detail. </p></li>
<li><p>If farmed, what was it fed – and from where did this feed originate? The feed should be from a sustainable source of fish, and perhaps even certified itself. </p></li>
<li><p>If wild-caught, is there minimal by-catch associated with it? </p></li>
<li><p>Which species of salmon is it? Whether Atlantic, chinook, sockeye, pink, coho or chum, sustainability depends on a variety of factors so there is no hard-and-fast rule. But there are better and worse options: <a href="https://www.seafoodwatch.org/recommendations/download-consumer-guides/sustainable-salmon-guide">this guide</a> from Seafood Watch is very useful. </p></li>
<li><p>Which eco-labels does it have? Certifications from the <a href="https://www.msc.org/uk">Marine Stewardship Council</a> and <a href="https://asc-aqua.org/">Aquaculture Stewardship Council</a> are best. </p></li>
</ul>
<h2>The scale of salmon</h2>
<p>While it’s best to choose locally sourced fish where possible, many salmon-loving populations live far from the <a href="https://www.tandfonline.com/doi/full/10.1080/00130095.2018.1506700?needAccess=true">hotspots of salmon production</a>. Sushi salmon in Japan, for example, may have travelled <a href="https://www.nature.com/articles/d42473-023-00290-7">17,000 km</a> from Norwegian or Chilean farms. And an estimated <a href="https://www.sciencedirect.com/science/article/pii/S0306919223000507#bi005">52%</a> of emissions from the production of 1 kilogram of farmed salmon in Norway comes from its air transport to China for consumption. </p>
<p>The need to mitigate the carbon footprint of salmon production will only increase as the world ramps up decarbonisation efforts. With an <a href="https://www.un.org/en/global-issues/population">increasing global population</a>, pressure on the already over-exploited wild salmon stocks is set to intensify.</p>
<p>Salmon farming or aquaculture currently bridges this gap between supply and demand, accounting for <a href="https://www.intechopen.com/chapters/79617">70%</a> of the salmon available for consumption. As the <a href="https://www.intechopen.com/chapters/79617">fastest-growing food</a> production system, the salmon farming industry is projected to reach a value of <a href="https://www.researchandmarkets.com/report/salmon?utm_source=CI&utm_medium=PressRelease&utm_code=fzgfsf&utm_campaign=1851063+-+Global+Salmon+Market+Report+2023:+Sector+to+Reach+$37.4+Billion+by+2027+at+a+3.9%2525+CAGR&utm_exec=como322prd">US$37 billion</a> (£29 billion) globally by 2027. </p>
<p>We need to fundamentally change our relationship with seafood if we are to preserve this wonderful natural food resource. We don’t have to stop eating salmon but we must make smarter decisions, both at the fish counter and within seafood supply chains. </p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Knowing which fish to buy can be confusing, but certain eco-labels can help decipher whether wild-caught, farmed or organic salmon is best for the environment.Laurence Wainwright, Departmental Lecturer and Course Director, Smith School of Enterprise and the Environment, University of OxfordNatasha Lutz, PhD in Disturbance Ecology and Machine Learning, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2193972024-02-06T21:38:09Z2024-02-06T21:38:09ZA 380-million-year old predatory fish from Central Australia is finally named after decades of digging<figure><img src="https://images.theconversation.com/files/568893/original/file-20240111-21-jl663h.jpg?ixlib=rb-1.1.0&rect=609%2C0%2C2039%2C1138&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Harajicadectes cruises through the ancient rivers of central Australia ~385 million years ago.</span> <span class="attribution"><span class="source">Brian Choo</span></span></figcaption></figure><p>More than 380 million years ago, a sleek, air-breathing predatory fish patrolled the rivers of central Australia. Today, the sediments of those rivers are outcrops of red sandstone in the remote outback.</p>
<p>Our new paper, published in the <a href="https://www.tandfonline.com/doi/full/10.1080/02724634.2023.2285000">Journal of Vertebrate Paleontology</a>,
describes the fossils of this fish, which we have named <em>Harajicadectes zhumini</em>. </p>
<p>Known from at least 17 fossil specimens, <em>Harajicadectes</em> is the first reasonably complete bony fish found from Devonian rocks in central Australia. It has also proven to be a most unusual animal.</p>
<h2>Meet the biter</h2>
<p>The name means “Min Zhu’s Harajica-biter”, after the location where its fossils were found, its presumed predatory habits, and in honour of eminent Chinese palaeontologist <a href="http://english.ivpp.cas.cn/people/members/202305/t20230530_331150.html">Min Zhu</a>, who has made many contributions to <a href="https://theconversation.com/a-kung-fu-kick-led-researchers-to-the-worlds-oldest-complete-fish-fossils-heres-what-they-found-190749">early vertebrate research</a>. </p>
<p><em>Harajicadectes</em> was a fish in the <a href="https://en.wikipedia.org/wiki/Tetrapodomorpha">Tetrapodomorpha</a> group. This group had strongly built paired fins and usually only a single pair of external nostrils.</p>
<p>Tetrapodomorph fish from the Devonian period (359–419 million years ago) have long been of great interest to science. They include the forerunners of modern tetrapods – animals with backbones and limbs such as amphibians, reptiles, birds and mammals.</p>
<p>For example, recent fossil discoveries show fingers and toes arose <a href="https://www.nature.com/articles/s41586-020-2100-8">in this group</a>. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-fish-gave-us-the-finger-this-ancient-four-limbed-fish-reveals-the-origins-of-the-human-hand-129072">When fish gave us the finger: this ancient four-limbed fish reveals the origins of the human hand</a>
</strong>
</em>
</p>
<hr>
<p>Devonian fossil sites in <a href="https://www.youtube.com/watch?v=LnHVPgvrn2M">northwestern</a> and <a href="https://australian.museum/learn/australia-over-time/fossils/sites/canowindra/">eastern</a> Australia have produced many spectacular discoveries of early tetrapodomorphs.</p>
<p>But until our discovery, the poorly sampled interior of the continent had only offered tantalising fossil fragments. </p>
<h2>A long road to discovery</h2>
<p>Our species description is the culmination of 50 years of tireless exploration and research. </p>
<p>Palaeontologist Gavin Young from the Australian National University made the initial discoveries in 1973 while exploring the Middle-Late Devonian Harajica Sandstone on Luritja/Arrernte country, more than 150 kilometres west of Alice Springs (Mparntwe).</p>
<p>Packed within red sandstone blocks on a remote hilltop were hundreds of fossil fishes. The vast majority of them were small <em>Bothriolepis</em> – a type of widespread prehistoric fish known as a <a href="https://en.wikipedia.org/wiki/Placodermi">placoderm</a>, covered in box-like armour.</p>
<p>Scattered among them were fragments of other fishes. These included <a href="https://bioone.org/journals/Acta-Palaeontologica-Polonica/volume-54/issue-4/app.2008.0057/A-New-Genus-of-Lungfish-from-the-Givetian-Middle-Devonian/10.4202/app.2008.0057.full">a lungfish known as <em>Harajicadipterus youngi</em></a>, named in honour of Gavin Young and his years of work on material from Harajica.</p>
<p>There were also spines from acanthodians (small, vaguely shark-like fish), the plates of phyllolepids (extremely flat placoderms) and, most intriguingly, jaw fragments of a previously unknown tetrapodomorph. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565947/original/file-20231215-21-3lshgi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The moment of discovery when we found a complete fossil of <em>Harajicadectes</em> in 2016. Flinders University palaeontologists John Long (centre), Brian Choo (right) and Alice Clement (left) with ANU palaeontologist Gavin Young (top left).</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>Many more partial specimens of this Harajica tetrapodomorph were collected in 1991, including some by the late palaeontologist <a href="https://www.smh.com.au/national/the-man-who-found-4000-fish-fossils-in-a-nsw-country-town-20231205-p5ep2m.html">Alex Ritchie</a>.</p>
<p>There were early attempts at figuring out the species, but this proved troublesome. Then, our Flinders University expedition to the site in 2016 yielded the first almost complete fossil of this animal.</p>
<p>This beautiful specimen demonstrated that all the isolated bits and pieces collected over the years belonged to a single new type of fish. It is now in the collections of the Museum and Art Gallery of the Northern Territory, serving as the <a href="https://museum.wa.gov.au/explore/blogs/museumcollections/what-type-specimen">type specimen</a> of <em>Harajicadectes</em>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sandstone image of a fish shape along with two graphics showing it in more detail" src="https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567575/original/file-20240102-21-i0b5nl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The type specimen of <em>Harajicadectes</em> discovered in 2016.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>A strange apex predator</h2>
<p>Up to 40 centimetres long, <em>Harajicadectes</em> is the biggest fish found in the Harajica rocks. Likely the top predator of those ancient rivers, its big mouth was lined with closely-packed sharp teeth alongside larger, widely spaced triangular fangs.</p>
<p>It seems to have combined anatomical traits from different tetrapodomorph lineages via convergent evolution (when different creatures evolve similar features independently). An example of this are the patterns of bones in its skull and scales. Exactly where it sits among its closest relatives is difficult to resolve. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large fish seen on the bottom of the sea with two smaller armoured fish underneath it" src="https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=781&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=781&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=781&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=981&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=981&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569190/original/file-20240114-27-x8x87i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=981&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Artist’s reconstruction of <em>Harajicadectes</em> menacing a pair of armoured <em>Bothriolepis</em>.</span>
<span class="attribution"><span class="source">Artist: Brian Choo</span></span>
</figcaption>
</figure>
<p>The most striking and perhaps most important features are the two huge openings on the top of the skull called spiracles. These typically only appear as minute slits in most early bony fishes.</p>
<p>Similar giant spiracles also appear in <a href="https://en.wikipedia.org/wiki/Gogonasus"><em>Gogonasus</em></a>, a marine tetrapodomorph from the famous Late Devonian Gogo Formation of Western Australia. (It doesn’t appear to be an immediate relative of <em>Harajicadectes</em>.)</p>
<p>They are also seen in the unrelated <a href="https://onlinelibrary.wiley.com/doi/am-pdf/10.1002/spp2.1243"><em>Pickeringius</em></a>, an early ray-finned fish that was also at Gogo.</p>
<h2>The earliest air-breathers?</h2>
<p>Other Devonian animals that sported such spiracles were the famous elpistostegalians – freshwater tetrapodomorphs from the Northern Hemisphere such as <a href="https://en.wikipedia.org/wiki/Elpistostege"><em>Elpistostege</em></a> and <a href="https://en.wikipedia.org/wiki/Tiktaalik"><em>Tiktaalik</em></a>.</p>
<p>These animals were extremely close to the ancestry of limbed vertebrates. So, enlarged spiracles seem to have arisen independently in at least four separate lineages of Devonian fishes.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=628&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=628&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=628&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=789&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=789&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567607/original/file-20240102-21-evllkl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=789&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The skull of <em>Harajicadectes</em> seen from above, showing the enormous spiracles.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>The only living fishes with similar structures are bichirs, African ray-finned fishes that live in shallow floodplains and estuaries. It was recently confirmed <a href="https://theconversation.com/now-listen-air-breathing-fish-gave-humans-the-ability-to-hear-21324">they draw surface air through their spiracles</a> to aid survival in oxygen-poor waters.</p>
<p>That these structures appeared roughly simultaneously in four Devonian lineages provides a fossil “signal” for scientists attempting to reconstruct atmospheric conditions in the distant past.</p>
<p>It could help us uncover the evolution of air breathing in backboned animals.</p><img src="https://counter.theconversation.com/content/219397/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brian Choo receives funding from the Australian Research Council and is employed by Flinders University.</span></em></p><p class="fine-print"><em><span>Alice Clement receives funding from the Australian Research Council and is employed by Flinders University.</span></em></p><p class="fine-print"><em><span>John Long receives funding from The Australian Research Council.</span></em></p>For decades, the sandstone in central Australia yielded tantalising segments of some sort of fossil fish. Now, we have finally pieced together a complete picture of this remarkable species.Brian Choo, Postdoctoral fellow in vertebrate palaeontology, Flinders UniversityAlice Clement, Research Associate in the College of Science and Engineering, Flinders UniversityJohn Long, Strategic Professor in Palaeontology, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2216552024-02-06T14:27:03Z2024-02-06T14:27:03ZMicroplastics found in Nile River’s tilapia fish: new study<figure><img src="https://images.theconversation.com/files/570625/original/file-20240122-15-ncnbn9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fisherman on the River Nile.</span> <span class="attribution"><span class="source">Khaled Desouki/AFP via Getty Images</span></span></figcaption></figure><p>The Nile is one of the world’s most famous rivers. It’s also Africa’s most important freshwater system. <a href="https://www.rti.org/impact/nile-river-basin-initiative#:%7E:text=The%20longest%20river%20in%20the,%2C%20Rwanda%2C%20Burundi%2C%20Tanzania%2C">About 300 million people</a> live in the 11 countries it flows through. Many rely on its waters for agriculture and fishing to make a living. </p>
<p>The Nile’s two main tributaries, the Blue Nile and the White Nile, come together in Sudan’s capital city, Khartoum. This industrial hub has <a href="https://worldpopulationreview.com/world-cities/khartoum-population">grown rapidly over the past few decades</a>.</p>
<p>The Nile is not immune to the same pollutants that affect rivers all over the world. Plastic debris is of particular concern. Over time plastics break down into smaller pieces known as microplastics. These are tiny plastic particles with a maximum size of five millimetres, all the way down to the nanoscale. <a href="https://www.nature.com/articles/s41467-023-40501-9">Recent research</a> found that</p>
<blockquote>
<p>rivers are modelled to export up to 25,000 tons of plastics from their sub-basins to seas annually. Over 80% of this amount is microplastic.</p>
</blockquote>
<p>This has huge negative consequences for biodiversity and the climate. As microplastics degrade, scientists have found, they <a href="https://www.sciencedirect.com/science/article/abs/pii/S2213343722019200">produce greenhouse gases</a>. Airborne microplastics may influence the climate by scattering and absorbing solar and terrestrial radiation, <a href="https://www.wired.com/story/microplastics-may-be-cooling-and-heating-earths-climate/">leading to atmospheric warming or cooling</a> depending on particle size, shape and composition. It also negatively affects <a href="https://www.undp.org/kosovo/blog/microplastics-human-health-how-much-do-they-harm-us">animal and human health</a>. Microplastics <a href="https://pubs.acs.org/doi/10.1021/envhealth.3c00052">have been shown</a> in laboratory studies to be toxic to animals and cells. </p>
<p>Much of the research about microplastics in African waters has focused on marine and coastal areas. To address this gap, I <a href="https://www.cell.com/heliyon/pdf/S2405-8440(23)10601-3.pdf">conducted a study</a> to assess the presence of microplastics in the River Nile in Khartoum. My students and I tested for the presence of microplastics in Nile tilapia. This popular African freshwater fish species <a href="https://www.mdpi.com/2071-1050/14/2/974">forms the basis</a> of commercial fisheries in many African countries, including Sudan.</p>
<p>The results do not make for happy reading. In the 30 freshly caught fish we surveyed, we found a total of 567 microplastic particles. This shows that the River Nile is contaminated with microplastics that can be consumed or absorbed in various ways by the tilapia and other aquatic organisms.</p>
<h2>Our sample</h2>
<p>The fish used in our study were caught just after the meeting point of the two Niles, known in Arabic as Al-Mogran. </p>
<p>We visited the Al-Mawrada fish market in the Omdurman area, which is also alongside the Nile. All 30 specimens we bought were freshly caught. </p>
<p>We dissected the fish to remove their digestive tracts. The individual tracts were treated so they would digest any organic matter they contained without interfering with the analysis of microplastics. The resulting solution was subject to another extraction procedure and we then conducted physical and chemical analyses.</p>
<p>Every specimen had microplastics in its digestive tract.</p>
<p>The number ranged from as few as five to as many as 47 particles per single fish. In total we identified 567 particles. This is high compared to <a href="https://www.sciencedirect.com/science/article/abs/pii/S0045653520331659">studies</a> that have <a href="https://www.researchsquare.com/article/rs-2430557/v1">reported microplastics</a> in tilapia species in other rivers and lakes. There is, as yet, no global guideline or standard for what might be an “acceptable” number.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fish-in-a-major-south-african-river-are-full-of-microplastics-186017">Fish in a major South African river are full of microplastics</a>
</strong>
</em>
</p>
<hr>
<h2>Shape, size and colour</h2>
<p>We detected different sizes of microplastics (0.04mm to 4.94mm), shapes (fibres, fragments, films, foams and pellets) and colours. The most common were very small (less than 1mm), fibrous – they appear slender and elongated – and coloured (dyed).</p>
<p>These characteristics make sense because of how fish and other aquatic organisms feed. Nile tilapia are versatile feeders: they consume a variety of organisms including phytoplankton, aquatic plants, invertebrates, detritus, bacterial films, as well as other fish and fish eggs. That puts them at a high risk of ingesting microplastics.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lagos-beaches-have-a-microplastic-pollution-problem-128133">Lagos beaches have a microplastic pollution problem</a>
</strong>
</em>
</p>
<hr>
<p>Nile tilapia are also more likely to consume particles that are within a similar size range as their natural prey, as well as the same shape and colour.</p>
<p>Smaller microplastics are especially good carriers for other pollutants such as heavy metals, resulting in additional health risks. Their small size also makes it easier for them to move into organs like the liver. Studies have found microplastics in the tissues, muscles, livers, blubber and lungs of other <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X15002581">aquatic</a> as well as <a href="https://www.sciencedirect.com/science/article/pii/S026974912301254X">marine mammal species</a>.</p>
<p>Fibres, the most dominant shape found in our specimens, stay in the intestine for longer than other microplastic shapes. This, too, can lead to health problems for the fish. Coloured microplastics contain dyes, many of which <a href="https://link.springer.com/article/10.1007/s13762-023-05168-1">contain toxic chemicals</a>. </p>
<p>This all has serious implications for human health, as people catch and eat the fish, which introduces those <a href="https://www.intechopen.com/chapters/86342">microplastics and associated chemicals into their bloodstreams</a>.</p>
<h2>Pollution sources</h2>
<p>Where does all this plastic originate? For starters, 65% of plastic waste in Khartoum is disposed of in <a href="https://www.ijsr.net/archive/v4i3/SUB151879.pdf">open dumps</a>. From there, it contaminates water bodies and other parts of the environment.</p>
<p>The city’s wastewater treatment system is ineffective. The three wastewater treatment plants in Khartoum state, Karary, Wd-Daffiaa and Soba, are outdated and <a href="https://www.sciencedirect.com/science/article/abs/pii/S2214785321069704?via%3Dihub">do not meet local and international standards</a>. That means untreated effluent from domestic, industrial and agricultural activities is another probable source of microplastic pollution.</p>
<p>There are also countless recreational sites along the River Nile in Khartoum. The Nile Street is the most popular in the capital city, hosting water sports, restaurants, cafes, clubs, event venues and hotels, as well as the tea ladies (women who serve hot beverages from makeshift mobile cafes along the banks of the river). However, waste disposal and collection practices are sorely lacking, so plastic litter from these leisure activities leaks into the river.</p>
<h2>No easy fix</h2>
<p>Tackling microplastic pollution is not easy. It will require technological advances, as well as the collective efforts of consumers, producers, governments and the scientific community.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/plastic-pollution-in-nigeria-is-poorly-studied-but-enough-is-known-to-urge-action-184591">Plastic pollution in Nigeria is poorly studied but enough is known to urge action</a>
</strong>
</em>
</p>
<hr>
<p>As consumers, we need to change our behaviour around plastic products, especially single-use plastics. For example, opt for fabric shopping bags instead of plastic bags; use glass and metal containers. Recycling is also important.</p>
<p>Governments must enforce waste management regulations and improve waste management practices, as well as helping to improve public awareness. Strategies and policies must explicitly feature microplastics.</p>
<p>Scientists can not only fill the knowledge gaps around microplastics. Communicating scientific findings is crucial; so too is developing innovations to protect against microplastics and their harmful effects.</p>
<p><em>I would like to thank and acknowledge my student Hadeel Alamin, who conducted this study with me.</em></p><img src="https://counter.theconversation.com/content/221655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The project was funded by the Royal Society – UK.</span></em></p>The River Nile is contaminated with microplastics.Dalia Saad, Researcher, School of Chemistry, University of the Witwatersrand, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2218062024-02-02T17:35:14Z2024-02-02T17:35:14ZHow trophy fishing can have a sustainable future<figure><img src="https://images.theconversation.com/files/572280/original/file-20240130-29-g3zie3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blue sharks are popular targets of a catch-and-release fishery along the southern coast of England</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/magnificent-blue-shark-elegant-proud-look-2318078271">Vladimir Turkenich/Shutterstock</a></span></figcaption></figure><p>It was 1984, and a hot tropical sun beat down on the inky blue depths of the Huon Gulf, a large inlet of the Solomon Sea just off the coast of Papua New Guinea. Suddenly, the peace was broken by the scream of a fishing reel as a four-metre-long blue marlin (<em>Makaira mazaraburst</em>) burst from the water. </p>
<p>For the next hour the giant fish surged, leapt and tail walked, as my best friend and fishing companion mostly just held on. Then, suddenly, it was gone. </p>
<p>The trace had frayed. No fishermen likes to lose a fish, but for me, there was also a sense of relief that it had got away. That fish was the most magnificent creature I’d ever seen, and that moment helped inspire my lifelong career in marine biology.</p>
<p>Recreational fishing for the largest species and individual fish in the sea like this is often called trophy fishing. Anglers seek to set new size records, either overall or using particular line strengths. These can be incredible specimens – the <a href="https://www.marlinmag.com/biggest-marlin-ever-caught/">largest marlin ever caught</a> weighed over 700kg, similar to a small car. </p>
<h2>What’s the catch?</h2>
<p><a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.4051">In a new paper</a>, we analysed 80 years of trophy fishing world records, using data recorded by the International Game Fishing Association (IGFA) to reveal some intriguing trends. Notably, in the 1950s, the average record-holding fish weighed a hefty 168kg, but this figure fell drastically to just 8kg in the 2010s. </p>
<p>The fish are not shrinking, instead anglers are now targeting a broader range of smaller species. However, this might signal a concerning decline in the population of larger fish species.</p>
<p>There has also been a noticeable expansion of trophy fishing worldwide. While the US dominated the scene historically, recent decades have seen an uptick in records from regions like Japan and New Zealand. </p>
<p>This global spread offers potential social and economic benefits to these new areas, but also raises concerns about increased fishing pressure on local fish populations that were previously less targeted.</p>
<p>Perhaps our most significant observation was the sharp decline in new records for fish species listed as threatened with extinction by the International Union for Conservation of Nature. Comparing the last decade (2010–2018) to the 2000s, there has been a roughly 66% decrease in records for these at-risk species. </p>
<p>This trend could indicate a growing awareness towards conservation issues in trophy fishing or could reflect the worrying reality of diminished populations of these species. The exact implications of this trend are yet to be fully understood.</p>
<p>Trophy fishing is controversial. Some people will never be fans. The largest fish in the ocean are often <a href="https://academic.oup.com/icesjms/article/71/8/2171/748104">the most productive breeders</a>, so catching and killing them, especially threatened species, doesn’t make sense. However, while world record fish accredited by the IGFA gain the spotlight, they account for a very small number of fish in total. </p>
<p>Much more concerning are the fishing tournaments that offer <a href="https://www.bisbees.com/News/Article/166">highly lucrative prizes</a> for landing the largest and most fish and <a href="https://sharkallies.org/shark-fishing-tournaments">sharks</a> in a given period of time. </p>
<h2>Tackling sustainability</h2>
<p>Trophy fishing, and sport fishing in general, is changing to become more sustainable, and even a force for good. In 2011, the IGFA introduced the <a href="https://igfa.org/announcement/igfa-launches-all-tackle-length-record-release-category/">“all-tackle length” category</a>. This approach records the length of the fish rather than weight, enabling it to be released without needing to kill it. </p>
<p>The Shark Angling Club of Great Britain has been releasing all sharks for decades and the <a href="https://anglingtrust.net/2023/11/22/update-from-british-record-fish-committee/">British Record Fish Committee</a> recently decided to only allow length-based records for large sharks, with fish having to be measured while still in the water. Although releasing fish does not guarantee survival, that can be maximised by using <a href="https://academic.oup.com/conphys/article/11/1/coad100/7503354">the right gear and careful handling</a>. Such approaches should become mandatory for all trophy anglers.</p>
<p>Anglers dedicate extensive time to their passion, developing a wealth of knowledge about the fish they catch. Harnessing this expertise is crucial for better estimating the extent of trophy fishing and increasing knowledge of fish stocks in general. </p>
<p>In the UK, anglers and scientists are working together through initiatives such as <a href="https://anglingtrust.net/sea/sea-angling-science/shark-hub-uk/">Shark Hub UK</a> and <a href="https://anglingtrust.net/sea/sea-angling-science/pollack-project/">Project Pollack</a> to gather catch data, collect samples and tag fish. </p>
<p>This approach not only aids conservation efforts but also aligns with the anglers’ interest in maintaining healthy fish populations for the future. After all, the recreational fisheries are not only a source of livelihood but also contribute to the <a href="https://www.mdpi.com/2673-3986/4/3/30">mental and physical wellbeing</a> of those who engage with them.</p>
<p>Nearly 40 years after that experience in Papua New Guinea, I marvelled at huge schools of giant fish off the coast of southern England last summer. These Atlantic bluefin tuna (<em>Thunnus thynnus</em>) have had <a href="https://academic.oup.com/icesjms/article/78/5/1672/6231587?login=false">a remarkable recovery</a> around the coast, most likely due to a combination of improved management and changing environmental conditions. </p>
<p>From this year, the UK government has authorised a <a href="https://www.gov.uk/government/news/recreational-fishing-for-atlantic-bluefin-tuna-set-to-start-in-english-waters-next-year#:%7E:text=Each%20UK%20fisheries%20administration%20will,commercial%20fishery%20for%20bluefin%20tuna.">catch and release only recreational fishery</a> for these fish. With continued careful management this should bring exciting angling, social and economic benefits for years to come.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<hr><img src="https://counter.theconversation.com/content/221806/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bryce Stewart receives funding from Defra and UK Research and Innovation. He is a member of the Marine Conservation Society and the Yorkshire Wildlife Trust and sits on the Marine Stewardship Council Stakeholder Advisory Council.</span></em></p><p class="fine-print"><em><span>James Boon does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Trophy fishing is a big threat to some of the most threatened species of fish, but there are ways to adapt the sport with marine conservation in mind.Bryce Stewart, Senior research fellow, Marine Biological AssociationJames Boon, PhD candidate in Marine Ecology, University of NottinghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2225112024-02-02T11:04:44Z2024-02-02T11:04:44ZGovernments spend US$22 billion a year helping the fishing industry empty our oceans. This injustice must end<figure><img src="https://images.theconversation.com/files/572830/original/file-20240201-27-sdoziy.jpg?ixlib=rb-1.1.0&rect=2%2C0%2C1370%2C770&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.pexels.com/photo/drone-view-of-fishing-trawler-on-sea-5829126/">Pok Rie/Pexel</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Overfishing has dire consequences for ocean health and for the millions of people who depend on fish for food and wellbeing. Globally, catch has been steadily <a href="https://www.nature.com/articles/ncomms10244">declining</a> since the 1990s. It’s a trend that’s likely to continue if we fail to act now.</p>
<p>Nearly all governments, including Australia’s, subsidise their fishing industries. Financial support comes in many forms, from taxpayer-funded fuel to reduced boat-building costs. These subsidies are harmful because they encourage overfishing. Some of the most environmentally damaging and least efficient fishing activities, such as <a href="https://www.sciencedirect.com/science/article/abs/pii/S0308597X09001663">bottom trawling</a> and <a href="https://www.science.org/doi/full/10.1126/sciadv.aat2504">distant water fishing</a>, would become unprofitable and cease without government <a href="https://archives.nereusprogram.org/ask-an-expert-why-is-the-global-fishing-industry-given-35-billion-in-subsidies-each-year/">subsidies</a>. </p>
<p>Scientists worldwide are rallying for stringent regulations to eliminate harmful fisheries subsidies, which totalled a whopping <a href="https://www.sciencedirect.com/science/article/pii/S0308597X19303677">US$22 billion</a> in 2018. Safeguarding the ocean will strengthen food security and allow more equitable distribution of marine resources.</p>
<p>Trade ministers from around the world are set to convene later this month in Abu Dhabi at a key meeting of the World Trade Organization (WTO). In an <a href="https://www.nature.com/articles/s44183-024-00042-0">open letter</a> published today, we are among 36 marine experts calling on the WTO to adopt ambitious regulations promoting fisheries sustainability and equity, and to eliminate harmful fisheries subsidies.</p>
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Read more:
<a href="https://theconversation.com/putting-an-end-to-billions-in-fishing-subsidies-could-improve-fish-stocks-and-ocean-health-163470">Putting an end to billions in fishing subsidies could improve fish stocks and ocean health</a>
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<h2>A long-awaited agreement</h2>
<p>International pressure from scientists helped to broker an earlier agreement on fishing subsidies, which is yet to be ratified. </p>
<p>In October 2021, 300 experts published an <a href="https://www.science.org/doi/10.1126/science.abm1680">article in Nature</a> calling for an end to harmful subsidies in the fishing sector. </p>
<p>After decades of fruitless negotiations, the WTO finally reached an <a href="https://www.wto.org/english/tratop_e/rulesneg_e/fish_e/fish_factsheet_e.pdf">agreement on fisheries subsidies</a> in June 2022. </p>
<p>Once ratified by two-thirds of WTO members, this agreement will partially address the United Nations <a href="https://indicators.report/targets/14-6/">Sustainable Development Goal Target 14.6</a> to eliminate harmful subsidies.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man in a suit brings down the gavel after agreement was reached on fisheries subsidies at the WTO meeting in 2022." src="https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572831/original/file-20240201-17-tiyvdp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The gavel goes down after members reached an agreement on fisheries subsidies, Geneva, 17 June 2022.</span>
<span class="attribution"><a class="source" href="https://www.wto.org/english/thewto_e/minist_e/mc12_e/photos_e.htm">WTO/Jay Louvion</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Unfortunately, while this agreement is historic, it is narrow. It only prohibits member governments from financing illegal fishing activities and the exploitation of already overfished stocks. But it’s obvious illegal fishing should be banned and the focus on overfished stocks is too little, too late. </p>
<p>Experts argue the agreement fails to specifically address harmful subsidies across global fisheries and as such only affects a <a href="https://oceana.org/blog/the-wto-agreement-saves-face-but-does-it-save-fish/">trivial component</a> of subsidy-driven exploitation. The subsidies that reduce operating costs and increase fishing capacity, allowing vessels to travel further and remain at sea longer, remain in place. </p>
<h2>Fisheries subsidies affect more than just fish</h2>
<p>Scientists have been <a href="https://www.nature.com/articles/s43016-021-00451-1">sounding the alarm</a> for decades. Many published studies document the <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020239">destabilising effects</a> of fisheries subsidies on ecosystems. In addition to impacting biodiversity and ecosystems, subsidies also increase the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0921800921001154">CO₂ emissions</a> that contribute to climate change.</p>
<p>More recently, studies have also applied a social perspective to this issue. Seafood lifts millions of people out of hunger, malnutrition and poverty. Yet more people will lose a secure <a href="https://www.nature.com/articles/534317a">source of food and nutrients</a> if fish stocks continue to decline due to industrial overfishing. </p>
<p>Research shedding light on the concept of “<a href="https://www.sciencedirect.com/science/article/pii/S0308597X20302529">equity</a>” shows subsidies don’t just harm the ocean, they also affect human <a href="https://www.worldwildlife.org/stories/5-ways-harmful-fisheries-subsidies-impact-coastal-communities">communities</a>. These communities are largely in developing countries which are rarely the source of harmful fisheries subsidies. Rather, their waters are exploited by <a href="https://oceana.org/wp-content/uploads/sites/18/OceanaDWF_FinalReport.pdf">foreign vessels</a> supported by wealthy governments’ fisheries subsidies.</p>
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<a href="https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Person wearing gloves, bending down to handle drying squid on a fish net" src="https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572832/original/file-20240201-25-bknp4o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Fisheries contribute to livelihoods and food security of millions of people.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/person-drying-squid-on-fishnet-13243896/">Jimmy Liao/Pexel</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Fisheries subsidies foster unfair competition not only among countries but also between industrial and community led fishing fleets. In the <a href="https://www.nature.com/articles/s44183-023-00031-9">Indian Ocean</a>, the level of subsidies provided to industrial fisheries corresponds to the amount of seafood exported to international markets, largely supplying rich and food-secure countries. This shows governments are deliberately empowering their industrial fleets to fish for seafood largely exported and consumed elsewhere, instead of sustaining fisheries providing food for locals. </p>
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Read more:
<a href="https://theconversation.com/fisheries-subsidies-fuel-ocean-depletion-and-hurt-coastal-communities-142260">Fisheries subsidies fuel ocean depletion and hurt coastal communities</a>
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<h2>The good, the bad and the ugly</h2>
<p>While most nations contribute to harmful subsidies, <a href="https://oceana.org/wp-content/uploads/sites/18/994812/Oceana_Summary6-22.pdf">ten nations</a> are responsible for 70% of this unsustainable financing. Chief among them are China, Japan and the European Union, reflecting the significant size of their distant water fishing fleets that typically access the resources of less-developed nations.</p>
<p>In contrast, <a href="https://www.sciencedirect.com/science/article/pii/S0308597X19303677?via%3Dihub">Australia</a> contributes only 0.1% of global harmful subsidies. Only 6% of Australia’s annual US$400 million in fisheries subsidies is considered harmful. While Australia should give attention to its ongoing annual taxpayer contribution of US$25 million to the fishing sector, it is well placed to demonstrate global leadership on how fishing can deliver sustainable and equitable outcomes without harmful subsidies.</p>
<h2>An essential opportunity</h2>
<p>A <a href="https://www.wto.org/english/thewto_e/minist_e/mc13_e/mc13_e.htm">second wave</a> of negotiations on fisheries subsidies is expected during the WTO Ministerial Conference this February in Abu Dhabi. This conference represents an invaluable opportunity to better protect the ocean. </p>
<p>In anticipation of this meeting, <a href="https://www.nature.com/articles/s44183-024-00042-0">we are urging nations</a> to adopt more ambitious regulations that eliminate harmful subsidies, prioritising fisheries sustainability and ocean equity. </p>
<p>Harmful fisheries subsidies are not only unsustainable but profoundly unfair. Based on the extensive body of evidence, the WTO should agree to eliminate harmful subsidies once and for all.</p><img src="https://counter.theconversation.com/content/222511/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vania Andreoli received funding for her PhD research from the Australian Government Research Training Program Scholarship and The Jock Clough Marine Foundation through the Oceans Institute Robson and Robertson Award. </span></em></p><p class="fine-print"><em><span>Dirk Zeller supervises Vania Andreoli’s PhD, so his lab has indirectly received funding for this doctoral research from the Australian Government and the Jock Clough Marine Foundation.</span></em></p><p class="fine-print"><em><span>Jessica Meeuwig supervises Vania Andreoli's PhD so her lab has indirectly received funding for this doctoral research from the Australian Government and the Jock Clough Marine Foundation. </span></em></p>Governments all over the world are propping up overfishing. Now scientists have penned an open letter calling on trade ministers to implement stricter regulations against harmful fisheries subsidies.Vania Andreoli, PhD Candidate, The University of Western AustraliaDirk Zeller, Professor & Director, Sea Around Us - Indian Ocean, The University of Western AustraliaJessica Meeuwig, Wen Family Chair in Conservation, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2219312024-01-31T00:40:50Z2024-01-31T00:40:50ZA 365-million-year-old fish with an extreme underbite showcases vertebrate diversity<figure><img src="https://images.theconversation.com/files/572031/original/file-20240129-25-h41utn.jpg?ixlib=rb-1.1.0&rect=0%2C40%2C3000%2C2465&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist reconstruction of Alienacanthus malkowskii, a 365-million-year-old placoderm fish from Poland and Morocco.</span> <span class="attribution"><span class="source">(Beat Scheffold & Christian Klug)</span>, <span class="license">Author provided</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/a-365-million-year-old-fish-with-an-extreme-underbite-showcases-vertebrate-diversity" width="100%" height="400"></iframe>
<p>Vertebrates are defined as all animals that possess a vertebral column, or backbone. Most living vertebrates also possess jaws, teeth and paired fins or limbs.</p>
<p>Fossils of the earliest vertebrates help us understand not only how these features originated, but also how they evolved and diversified over time. </p>
<p>Our study, <a href="https://dx.doi.org/10.1098/rsos.231747">published in <em>Royal Society Open Science</em></a>, examines 365-million-year-old fossils of a fish with the world’s longest underbite, called <em>Alienacanthus malkowskii</em>. These fossils demonstrate the diversity of jawed vertebrates early on during their evolution.</p>
<p><em>Alienacanthus</em> is a member of an extinct group of fish called <a href="https://ucmp.berkeley.edu/vertebrates/basalfish/placodermi.html">placoderms</a>, which are some of the first jawed vertebrates. They are armoured fish of various shapes and sizes and are essential to understanding the evolution of vertebrates and their features, particularly jaws and teeth.</p>
<p>Together, placoderm jaws and teeth hold evidence of feeding strategies and diets, giving us insights into what and how some of our fishy ancestors ate. </p>
<h2>From spine to jaw</h2>
<p>In 1957, Polish paleontologist Julian Kulczycki <a href="https://www.app.pan.pl/article/item/app02-285.html">described fossil fishes</a> from the Polish Holy Cross mountains. Among these finds were two partially broken long thin bones which he thought were some weird-looking fin spines from a fish. The odd shape of the so-called spines gave the animal its name, <em>Alienacanthus</em>. </p>
<p>In the late 1990s to early 2000s, members of our research team came across some Moroccan specimens in the collections of the Muséum national d’Histoire naturelle in Paris that included the same bony elements. The team later encountered more specimens from Poland and Morocco, which we identified as belonging to a placoderm.</p>
<p><em>Alienacanthus</em> had a massive, rounded head with a pointy snout and large eyes. What Kulczycki had identified as spines turned out to be the lower jaws, which extended way past the closing of the mouth, unlike the upper jaws. The teeth were sharp, slightly curved towards the back to trap live prey, and the teeth continued past the closing of the mouth. </p>
<p>Unlike in other placoderms, the upper jaws of <em>Alienacanthus</em> were capable of a slight movement independently of the skull, helping to accommodate the lower jaw.</p>
<h2>Most extreme case</h2>
<p>The extended lower jaw of <em>Alienacanthus</em>, twice as long as the skull, is unique among placoderms and extremely rare in other living and fossil groups. In most animals, jaw protrusion is seen in the upper jaw, like in the <a href="https://www.britannica.com/animal/swordfish-fish">swordfish</a>, or both upper and lower jaws like <a href="https://theconversation.com/how-climate-change-killed-the-dinosaurs-underwater-cousins-55803">ichthyosaurs</a> or <a href="https://nationalzoo.si.edu/animals/gharial">gharials</a>. </p>
<p>Among living species, only a tiny fish called the <a href="https://www.britannica.com/animal/halfbeak">halfbeak</a> shows an elongated lower jaw. The halfbeak measures just five to 10 cm in length, while <em>Alienacanthus</em>’ head and jaws alone reach 80 cm. The relative length of the lower jaw is also 20 per cent greater than in the halfbeak.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a small fish with an elongated lower jaw" src="https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572030/original/file-20240129-29-wk61fi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Of currently living species, only the halfbeak shows an elongated lower jaw.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p><em>Alienacanthus</em> also holds the title of the oldest case of lower jaw elongation. The previous record belonged to the 310-million-year-old shark <a href="https://archive.org/details/newsharkoffamily161zang/page/n9/mode/2up"><em>Ornithoprion</em></a>. </p>
<h2>The Age of fishes</h2>
<p><em>Alienacanthus</em> and relatives lived during <a href="https://www.britannica.com/science/Devonian-Period">the Devonian period</a> (358 to 419 million years ago), also referred to by paleontologists as the <a href="https://eartharchives.org/articles/when-monsters-ruled-the-water-the-age-of-fishes/index.html">Age of fishes</a>. During this time, a variety of fish groups ruled the oceans, including <a href="https://www.nhm.ac.uk/discover/shark-evolution-a-450-million-year-timeline.html">sharks</a>, <a href="https://theconversation.com/its-less-than-2cm-long-but-this-400-million-year-old-fossil-fish-changes-our-view-of-vertebrate-evolution-96419">bony fishes</a>, <a href="https://eartharchives.org/articles/ostracoderms-armored-fishes-without-jaws/index.html">jawless fishes</a> and placoderms, which together illustrated a wide range of body, head and jaw shapes. </p>
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Read more:
<a href="https://theconversation.com/ancient-fishes-kept-their-young-in-a-nursery-65400">Ancient fishes kept their young in a nursery</a>
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<p><em>Alienacanthus</em> stretches that diversity to the limit with such a unique look. Fifteen million years after this animal’s occurrence, placoderms met their demise. </p>
<p>The evolution of more complex jaws allowed for a wider range of feeding and hunting methods. The oldest placoderms favoured a <a href="https://doi.org/10.1098/rsbl.2006.0569">fast-closing mouth</a> for catching prey. But some placoderms started <a href="https://doi.org/10.1111/j.1096-3642.1980.tb01932.x">feeding on durophagous animals, with hard shells and exoskeletons</a>, and others may have been <a href="https://doi.org/10.1098/rsos.200272">filter-feeders</a>. </p>
<p><em>Alienacanthus</em> used its sharp teeth to catch and trap live prey, possibly using its elongated jaw to confuse or injure its future meal, as seen in swordfish and some ichthyosaurs. </p>
<h2>Learning more</h2>
<p>The further back in time we go, the more our planet’s continents looked different. During the Late Devonian period, when <em>Alienacanthus</em> lived, Poland was situated on the northeastern coast and Morocco on the southern coast of a vast ocean. The presence of the same species on both ends shows that migration occurred in that ocean at that time, despite sea level fluctuation. </p>
<p><em>Alienacanthus</em> comprises just one of numerous recent finds in Poland and Morocco from the Late Devonian period. Such discoveries illustrate the remaining high potential for deposits of this age to reveal critical insights about early vertebrates.</p><img src="https://counter.theconversation.com/content/221931/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Melina Jobbins received funding from the Swiss National Science Foundation. </span></em></p><p class="fine-print"><em><span>Christian Klug receives funding from the Swiss National Science Foundation SNSF (grant nr. 200020_184894).</span></em></p><p class="fine-print"><em><span>Martin Rücklin received funding from Dutch Research Council (NWO).</span></em></p>What paleontologists had believed to be spiny fins turned out to be elongated jaws. New examination of fossils that were 365 million years old revealed a fish with a remarkable lower jaw.Melina Jobbins, Researcher, Evolutionary Biology, University of ZurichChristian Klug, Professor, Curator of the Palaentological Museum, University of ZurichMartin Rücklin, Research group leader, Naturalis Biodiversity Center and Senior researcher, Instituut Biologie Leiden, Leiden UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2217702024-01-30T13:19:19Z2024-01-30T13:19:19ZNigeria’s plastic ban: why it’s good and how it can work<p>Two weeks into January 2024, Nigerian authorities took steps to curb environmental degradation caused by plastic pollution in the country.</p>
<p>The <a href="https://von.gov.ng/environment-ministry-bans-single-use-plastics-at-headquarters-agencies/">Federal Ministry of Environment</a> and the Lagos State government both announced <a href="https://twitter.com/tokunbo_wahab/status/1749055962193744206">bans</a> on single-use plastics.</p>
<p>The Federal Ministry of Environment was the first to issue a directive. It banned single-use plastics in its own departments and agencies. The Lagos State government followed a few days later with a ban on styrofoam containers (popularly used for food packaging) and <a href="https://www.youtube.com/watch?v=OPr_5fdI_BQ">gave</a> businesses three weeks to mop up styrofoam in circulation.</p>
<p>The Abia State government in the south-east followed with its own <a href="https://dailypost.ng/2024/01/28/abia-govt-bans-take-away-foils/">ban</a> on single-use plastics, announced on 27 January. </p>
<p>Nigeria generates excessive amounts of <a href="https://www.mdpi.com/2071-1050/16/2/672#B9-sustainability-16-00672">plastic waste</a>, nearly 90% of which is <a href="https://www.mdpi.com/2071-1050/16/2/672">mismanaged</a>. </p>
<p>As an environmental toxicologist, I argue that there is enough research evidence showing the adverse effects of plastic waste on the environment – as well as potential harm to people – to support the ban. As a member of the Metrics Task Force of the <a href="https://www.globalplasticaction.org/nigeria">Nigeria National Plastic Action Plan</a>, among others, I have been part of several stakeholder <a href="https://www.linkedin.com/feed/update/urn:li:activity:7066392385236123649/">engagements</a> since 2022 across the plastic waste value chain, contributing to the evidence on the severity of the plastic waste menace in Nigeria. </p>
<p>The challenge will be implementation. Nigeria has had a law in the pipeline banning single-use plastics <a href="https://www.greenpeace.org/africa/en/blogs/11156/34-plastic-bans-in-africa/">since 2013</a>. It has still not been <a href="https://www.greenpeace.org/africa/en/blogs/50697/the-negative-impact-of-plastic-in-nigeria-the-need-for-a-legal-framework/">promulgated</a> at the national level. </p>
<p>Nevertheless, the recent bans are being announced with <a href="https://punchng.com/lasg-gives-styrofoam-makers-three-weeks-to-clear-stock/#:%7E:text=The%20Lagos%20State%20Government%2C%20on,before%20the%20commencement%20of%20enforcement.">pledges</a> of <a href="https://businesspost.ng/general/abia-prohibits-use-of-styrofoam-foils-after-lagos/#:%7E:text=A%20statement%20issued%20over%20the,but%20the%20implementation%20was%20relaxed.">stringent implementation</a>.</p>
<p>To make it work this time, Nigeria could learn from other countries like <a href="https://www.no-burn.org/rwanda-plastic-ban/#:%7E:text=Rwanda%20was%20the%20first%20country,the%20issue%20of%20plastic%20pollution.">Rwanda</a> that have issued similar bans. It is also important to consider affordable alternatives and the human and financial resources that are needed to enforce the ban.</p>
<h2>Why banning single-use plastics is necessary</h2>
<p>Nigeria has been rather slow to tackle plastic pollution. This is despite research documenting the extent of plastic waste in the environment, which has <a href="https://www.wacaprogram.org/sites/waca/files/knowdoc/Nigeria_plastics_PWC_final%20%281%29.pdf#page=4">caused</a> pollution of rivers and water bodies and reduced fish populations.</p>
<p>We conducted a <a href="https://www.researchgate.net/profile/Temitope-Sogbanmu/publication/360677339_Plastic_Pollution_in_the_Environment_in_Nigeria_A_Rapid_Systematic_Review_of_the_Sources_Distribution_Research_Gaps_and_Policy_Needs/links/6291f3886886635d5caa425c/Plastic-Pollution-in-the-Environment-in-Nigeria-A-Rapid-Systematic-Review-of-the-Sources-Distribution-Research-Gaps-and-Policy-Needs.pdf">review</a> of about 40 studies, mostly in south-western Nigeria, that documented the sources and extensive distribution of plastic waste. </p>
<p>In more recent <a href="https://www.sciencedirect.com/science/article/pii/S277241662400010X?via%3Dihub">research we found</a> microplastics in Osun River, its sediments and fish. These tiny pieces of plastic are not degradable and can leach into living organisms when ingested, causing adverse effects.</p>
<p>A range of studies have documented various plastic waste types, forms, sizes and polymer compositions, especially highly hazardous ones. Hazardous plastic polymers have been found in potable water (<a href="https://www.tandfonline.com/doi/abs/10.1080/03067319.2021.1982926">bottled water</a> and <a href="https://jfqhc.ssu.ac.ir/article-1-483-en.html">sachet water</a>) and food such as (<a href="https://link.springer.com/article/10.1007/s11356-023-26410-w">fish</a> and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0075951119300970?via%20percent%203DDihub">snails</a>). They have also been found in <a href="https://www.sciencedirect.com/science/article/pii/S2468227622001272">surface waters</a>, sediments and air. </p>
<p>There is also evidence of a large quantity of uncollected plastic litter across major metropolises like <a href="https://www.researchgate.net/publication/361548692_REVIEWING_THE_CONCEPT_WASTE_HIERARCHY_GUIDELINE_AND_THE_ENVIRONMENTAL_PROBLEM_OF_WASTE_MANAGEMANET_IN_LAGOS_STATE_NIGERIA">Lagos</a> and Abuja. </p>
<p>And there’s evidence that single-use plastics make up most of the plastic waste across the country. An example is water sachets – about <a href="https://www.sciencedirect.com/science/article/abs/pii/B9780128178805000220?via%3Dihub">60 million</a> of these are used daily in Nigeria. </p>
<h2>Lessons from other countries</h2>
<p>Nigeria can learn from the mistakes and successes of other countries that have banned single-use plastics. </p>
<p>It is estimated that <a href="https://www.euronews.com/green/2023/04/05/really-encouraging-plastic-bag-bans-work-say-campaigners-where-is-europe-lagging-behind">over 100 countries globally</a> have partially or fully banned single-use plastics. African and Asian countries top the list. </p>
<p>About <a href="https://cadmus.eui.eu/bitstream/handle/1814/73207/PB_2021_21_STG.pdf?sequence=1&isAllowed=y#page=3">60%</a> of the countries in Africa have various bans on single-use plastics. Not all the countries have recorded <a href="https://cadmus.eui.eu/bitstream/handle/1814/73207/PB_2021_21_STG.pdf?sequence=1&isAllowed=y">successes</a>. </p>
<p>Rwanda is one African country that has <a href="https://www.undp.org/blog/umuganda-rwandas-audacity-hope-end-plastic-pollution#:%7E:text=The%20cleanliness%20is%20anchored%20in,is%20not%20an%20isolated%20law">succeeded</a>. The government used a top-down approach involving enforcement with stringent penalties and a bottom-up approach involving advocacy campaigns at the grassroots. </p>
<p>There have also been failures. In <a href="https://www.efdinitiative.org/publications/case-banning-single-use-plastics-malawi">Malawi</a>, the ban failed thrice mainly due to <a href="https://www.sciencedirect.com/science/article/pii/S2667010021000081?via%3Dihub">lack of robust stakeholder</a> consultation and national advocacy. </p>
<p>In Nigeria, affordable alternatives to single-use plastics should be made available in critical sectors such as pharmaceuticals, fast moving consumer goods, food manufacturing and processing.</p>
<h2>Enforcement</h2>
<p>For sustainable enforcement in Nigeria, the ban should be done sequentially. Non-essential uses, such as fizzy drinks and beverages packaging, should be targeted first. </p>
<p>This should be done while providing affordable alternatives and encouraging the production and use of sustainable materials. For example, potable water needs to be provided by the government at accessible and affordable prices as an alternative to sachet and plastic bottled water. </p>
<p>Strategic stakeholder engagement for monitoring, advocacy and buy-in is also key. It is important to carry along the private and informal sectors which drive the single-use plastics value chain. </p>
<p>Incentives to promote the adherence to this ban are important. The Federal Ministry of Environment is already leading this by <a href="https://punchng.com/govt-plans-to-stop-single-use-plastics/#:%7E:text=Kindly%20share%20this%20story%3A,Ministry%20of%20Environment%20in%20Abuja.">enforcing</a> the ban across its departments and agencies first.</p>
<p>The use of mainstream and social media platforms is important. And the judiciary and legal institutions must be engaged to support the enforcement, as was done in <a href="https://www.weforum.org/agenda/2020/11/q-a-reflecting-on-kenyas-single-use-plastic-bag-ban-three-years-on/">Kenya</a>. </p>
<p>Funds must be invested in sustainable local alternatives to single-use plastics. The aim would be to provide livelihoods. </p>
<p>Universities, polytechnics, and government research institutions such as the <a href="https://www.scienceandtech.gov.ng/parastatals/">Federal Ministry of Science, Technology and Innovation parastatals</a> should be funded to research and pilot innovative and affordable alternatives to single-use plastics. </p>
<p>Monitoring must be harmonised across states and national institutions to track progress. Open access digital platforms such as the <a href="https://eepon.unilag.edu.ng/">Environmental Evidence Portal for Nigeria</a> can be partnered by the government to make available contextual “Nigerian” evidence in non-technical formats for education and advocacy.</p><img src="https://counter.theconversation.com/content/221770/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Temitope O. Sogbanmu receives funding from the Association of Commonwealth Universities (ACU), Social Sciences and Humanities Research Council (SSHRC) Canada, Royal Academy of Engineering (RAE), among other. Her affiliations include the Nigeria National Plastic Action Partnership (NPAP) as a member of the Metrics Task Force, One Health and Development Initiative (OHDI) and the the Nigerian Young Academy (NYA).</span></em></p>Banning single-use plastics in Nigeria is a step in the right direction. But its success will depend on provisions made for enforcement.Temitope O. Sogbanmu, Senior Lecturer, Ecotoxicology and Conservation Unit, Department of Zoology, Faculty of Science, University of LagosLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2207602024-01-18T13:28:52Z2024-01-18T13:28:52ZNot all underwater reefs are made of coral − the US has created artificial reefs from sunken ships, radio towers, boxcars and even voting machines<figure><img src="https://images.theconversation.com/files/569704/original/file-20240116-27-b90elk.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C5682%2C3788&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The bow of the U.S. Coast Guard cutter Duane, a decommissioned ship deliberately sunk off Florida to serve as an artificial reef.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/bow-of-uscg-duane-royalty-free-image/492717259">Stephen Frink via Getty Images</a></span></figcaption></figure><p>When people hear about underwater reefs, they usually picture colorful gardens created from coral. But some reefs are anchored to much more unusual foundations. </p>
<p>For more than a century, people have placed a wide assortment of objects on the seafloor off the U.S. coast to provide habitat for marine life and recreational opportunities for fishing and diving. Artificial reefs have been created from decommissioned ships, chicken transport cages, concrete pipes, rail cars and more.</p>
<p>We study how ocean-dwelling fish <a href="https://scholar.google.com/citations?user=wZ-kv2AAAAAJ&hl=en">use artificial reefs</a> in the <a href="https://scholar.google.com/citations?user=WF8vzA4AAAAJ">U.S. and beyond</a>. Through our research, we have learned that artificial reefs can be hot spots for large predatory fish such as <a href="https://doi.org/10.1111/faf.12548">groupers</a> and <a href="https://doi.org/10.1371/journal.pone.0237374">jacks</a>. They also can serve as <a href="https://doi.org/10.1038/s42003-019-0398-2">stepping stones</a> for reef fish expanding their range northward with warming water temperatures and as <a href="https://doi.org/10.1002/ecy.2687">rest stops</a> for sharks. </p>
<p>Artificial reefs can be <a href="https://doi.org/10.1002/ecs2.3924">strategically designed and placed</a> to optimize fish habitat. But although they provide valuable ecological services, no one has inventoried how many of these structures exist in U.S. waters or how much seafloor they occupy.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Fish swim through a sunken ship doorway rimmed with coral as a scuba diver hovers nearby." src="https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569699/original/file-20240116-25-xly63u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A diver at the U.S. Coast Guard cutter Duane, which was decommissioned in 1985 and intentionally sunk in 1987 off Key Largo, Fla., to create reef habitat.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/diver-on-shipwreck-royalty-free-image/109010339">Stephen Frink/The Image Bank via Getty Images</a></span>
</figcaption>
</figure>
<p>To help fill this knowledge gap, we led a team of scientists and artificial reef directors from the 17 U.S. states with artificial reef-building programs in the first national calculation of artificial reef extent. Our <a href="https://www.nature.com/articles/s41893-023-01258-7">new study</a> shows that these reefs cover a total of about 7 square miles (19 square kilometers) of U.S. seafloor – an area equivalent to 3,600 football fields. We also describe the diversity of objects used to create reefs, as well as patterns in artificial reef creation over time.</p>
<h2>Creating modern artificial reefs</h2>
<p>Modern reefing is different from dumping trash into the water and is <a href="https://media.fisheries.noaa.gov/dam-migration/noaa_artificial_reef_guidelines.pdf">regulated at the federal and state levels</a>. A rigorous permitting and approval process ensures that the proposed objects or materials are appropriate to deploy in the ocean. </p>
<p>For example, decommissioned ships are thoroughly <a href="https://www.epa.gov/ocean-dumping/vessel-reef-projects">cleaned and drained of fuel and other polluting substances</a> prior to sinking to minimize environmental risks. Some materials that were once used to create artificial reefs, such as rubber, fiberglass, wood and plastic, are now prohibited because they may move from their placed location, damaging nearby habitat, or deteriorate quickly in salt water. </p>
<p>Reefed objects can be sunk only in predesignated areas of the U.S. seafloor. These zones, which are usually sandy sea bottom, total about 2,200 square miles (5,800 square kilometers) – roughly the area of Delaware.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/48Py7uILHHg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Seven months after the Texas Parks and Wildlife Dept.’s artificial reef program sank the Kraken, a decommissioned 371-foot cargo ship, divers found it heavily colonized by ocean life.</span></figcaption>
</figure>
<p>Each zone can support the creation of many individual reefs over multiple decades. Within a given zone, reefed objects are usually placed away from one another, separated by large swaths of sand. This maximizes the amount of sand habitat, where some reef fish forage.</p>
<p>The extent of artificial reefs in these zones has increased by about 2,000% over the past 50 years. Since 2010, however, artificial reef extent has grown only 12%. This is likely because of challenges in acquiring and sinking acceptable reef materials. It could also reflect a push toward <a href="https://theconversation.com/3d-printing-coral-reefs-can-create-new-habitat-but-it-doesnt-tackle-human-destruction-103927">developing structures</a> specifically for use as artificial reefs. </p>
<h2>Planes, trains and automobiles</h2>
<p>For our study, we gathered records of intentional reefings dating back to 1899 and occurring off artificial all U.S. coastal states, except for six without artificial ocean reef programs: Maine, New Hampshire, Connecticut, Oregon, Washington and Alaska.</p>
<p>For some of these events, especially in recent decades, there were detailed records of the sizes and quantities of sunken objects or seafloor maps from which we could derive these measurements. These reefs were easy to quantify. </p>
<p>Other records, including some from the early 20th century, had scant detail. For these, we developed an approach to estimate how much seafloor the reefs covered, based on similar deployments with better records.</p>
<p>Our study found a vast assortment of reefed objects on the U.S. seafloor. They included decommissioned tugboats, fishing vessels, barges, ferries and military vessels. Reefs have also been created from rail boxcars, aircraft, vehicles, chicken transport cages, voting machines, missile platforms, concrete pipes, radio towers, tires, limestone rocks and objects purposely designed as artificial reefs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A boat with a crane lowers pyramid-shaped structures into the water." src="https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569701/original/file-20240116-19-2hqu7p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Florida Fish and Wildlife Commission deploys artificial reef modules off the coast of Mexico Beach on April 6, 2013.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/eh6fXS">Florida Fish and Wildlife Commission/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Objects that occupy the largest amount of seafloor include limestone rocks, large concrete modules designed specifically for reefing, metal rigs and towers and long, narrow concrete pieces repurposed from their previous uses, such as culverts or bridges.</p>
<h2>Potential impacts</h2>
<p>After a reef is created, fish can appear within minutes or hours. The sequence of fish arrival sometimes <a href="https://doi.org/10.1016/j.ecoleng.2018.09.012">follows a pattern</a>. Transient fish such as jacks and barracuda come first, followed by bottom-dwelling fish such as grouper and smaller reef fish. With time, plants and animals grow on the hard surfaces of the artificial reef, helping to provide food and sanctuary for fish.</p>
<p>However, these reefs can also cause ecological harm. Invasive species, such as plants and other animals that grow on hard structures, can use artificial reefs to <a href="https://doi.org/10.1371/journal.pone.0038124">spread to new places</a>. </p>
<p>Artificial reefs also may attract fish away from nearby natural reefs. Since constructed reefs are often in prime recreational fishing locations, this could lead to higher catches of those species. </p>
<p>Another risk is that if artificial reefs are improperly placed or secured on the sea floor, they can shift into unintended areas and harm sensitive habitats, particularly in the aftermath of storms. For example, Florida <a href="https://www.theguardian.com/us-news/2015/may/22/florida-retrieving-700000-tires-after-failed-bid-to-create-artifical-reef">sank 1 million to 2 million tires offshore</a> in the 1970s in an effort to create artificial reefs, but sea life didn’t colonize them as intended. Now the tires are washing around and smothering coral.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/reel/CxvnpSdOnsr/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Learning from artificial reefs</h2>
<p>Monitoring how fish and other species use artificial reefs, especially compared with naturally occurring reefs, will be key for understanding benefits and risks from these structures. As <a href="https://theconversation.com/artificial-coral-reefs-showing-early-signs-they-can-mimic-real-reefs-killed-by-climate-change-new-research-215011">climate change</a> continues to alter ocean ecosystems, we see opportunities to learn which types of artificial reefs are best suited for enhancing habitat for particular sorts of fish. </p>
<p>For example, we know that large predators that dwell in open water, such as jacks, barracuda and sharks, tend to prefer <a href="https://doi.org/10.1371/journal.pone.0237374">taller artificial reefs over shorter ones</a>. This is similar to insights from oil rigs, showing that these vertical and complex structures are <a href="https://doi.org/10.1073/pnas.1411477111">valuable fish habitat</a>. More than 500 decommissioned oil rigs <a href="https://www.bsee.gov/what-we-do/environmental-compliance/environmental-programs/rigs-to-reefs">have been converted to reefs</a>. Our calculation included only those that are managed by state artificial reef programs. </p>
<p>Other structures in the water, such as <a href="https://theconversation.com/as-the-us-begins-to-build-offshore-wind-farms-scientists-say-many-questions-remain-about-impacts-on-the-oceans-and-marine-life-216330">offshore wind turbine foundations</a>, will <a href="https://youtu.be/0SBxDWuE1vY">likely form habitat for sea life</a> similarly to artificial reefs. Insights about what types of structures different fish prefer may help guide the design or location of offshore wind farms.</p>
<p>Humans rely on the ocean for many benefits, including food, commerce, energy and a stable climate. Measuring artificial reefs’ footprint is a first step toward understanding their effects, both good and bad, on ocean wildlife and human uses of the ocean.</p>
<p><em><a href="https://www.nature.org/en-us/about-us/where-we-work/united-states/virginia/stories-in-virginia/our-staff/">Brendan Runde</a>, a marine scientist at The Nature Conservancy, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/220760/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Artificial reefs are structures that humans put in place underwater that create habitat for sea life. A new study shows for the first time how much of the US ocean floor they cover.Avery Paxton, Research Marine Biologist, National Oceanic and Atmospheric AdministrationD'amy Steward, Master's Student in Biology, University of GuamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2164102024-01-10T14:16:10Z2024-01-10T14:16:10ZMating anchovies stir up the sea as much as a major storm – and it’s good for the environment too<figure><img src="https://images.theconversation.com/files/568398/original/file-20240109-21-v0brit.jpg?ixlib=rb-1.1.0&rect=1556%2C8%2C3891%2C3620&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/school-anchovies-swimming-deep-blue-sea-2292958167">ennar0/Shutterstock</a></span></figcaption></figure><p>Why would oceanographers ever care about anchovies having sex? We do because these small fish can help mix different layers of the ocean when they mate. This circulates nutrients, oxygen and greenhouse gases around different layers of the ocean, thereby sustaining the ecosystem.</p>
<p>Mixing layers of the ocean vertically requires energy. Most of this energy is provided by winds and tides. However, <a href="https://www.sciencedirect.com/science/article/pii/0011747166906024">research</a> that was conducted in 1966 found a mismatch between the energy required for mixing and the energy provided by available sources. </p>
<p>This prompted an intriguing question: can swimming animals such as fish and crustaceans fill the energy gap and contribute to ocean mixing?</p>
<p>After decades of mixed and extremely scarce evidence, the oceanographic community came close to reaching a verdict on the topic in 2019. A <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-marine-010318-095047">study</a> conducted by an American researcher called Eric Kunze concluded that biological mixing is extremely unlikely to happen. </p>
<p>The rationale for this conclusion is simple. Marine swimmers do create some turbulent eddies as they move around, but these eddies are too small to cause any substantial vertical mixing. Whirls shed by marine swimmers are so small that they are instead dissipated as heat due to friction between water molecules. </p>
<p>But in a <a href="https://www.nature.com/articles/s41561-022-00916-3">study</a> published in 2022, my colleagues and I challenged this conclusion. Our findings show that biological mixing can happen under certain circumstances.</p>
<figure class="align-center ">
<img alt="A boat sailing through a bay." src="https://images.theconversation.com/files/568401/original/file-20240109-27-n09bw7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568401/original/file-20240109-27-n09bw7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568401/original/file-20240109-27-n09bw7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568401/original/file-20240109-27-n09bw7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568401/original/file-20240109-27-n09bw7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568401/original/file-20240109-27-n09bw7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568401/original/file-20240109-27-n09bw7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Spanish research vessel Ramon de Margalef leaving the coast of Galicia in 2018.</span>
<span class="attribution"><span class="source">Bieito Fernández Castro</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>A surprising observation</h2>
<p>In July 2018, our team left the coast of Galicia in north-west Spain on a mission to understand if variations in ocean mixing conditions were to blame for the frequent occurrence of harmful algal blooms that threaten the region’s thriving mussel aquaculture industry. We measured water turbulence along with various ecological indicators every 30 minutes for 15 consecutive days. </p>
<p>We monitored turbulence by measuring fluctuations in the velocity and temperature of water at very small scales. These fluctuations are an indication of the intensity of turbulent motions and mixing respectively. To our surprise, we detected extremely high levels of turbulence every night, at a level similar to that caused by a major storm. </p>
<p>But, at the time of our study, the weather was calm and tides were weak. So what was happening? The key to unravelling this mystery came from the casual observation of screens in the lab onboard our research vessel. These screens show signals from the ship’s echo-sounder, an instrument designed to detect the presence of fish. </p>
<p>No one was paying much attention initially, since we were – in principle – not interested in fish. But the acoustic measurements revealed very strong echo signals that coincided with our strong nighttime turbulence measurements. This suggested that the strong nighttime turbulence was related to the presence of fish. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bongo-shaped nets being lowered into the sea." src="https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568400/original/file-20240109-27-ydgca9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The bongo-shaped nets used to capture tiny fish eggs.</span>
<span class="attribution"><span class="source">Bieito Fernández Castro</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>The obvious solution was to capture the fish. We used some of the small bongo-shaped nets designed to capture microscopic algae. </p>
<p>What we found in the nets caught us by surprise. They were full of thousands and thousands of tiny fish eggs, probably belonging to European <a href="https://www.britannica.com/animal/anchovy">anchovies</a>. </p>
<p>The circle was closed, the mystery solved. Hundreds of anchovies aggregated around our sampling station every night to mate and fertilise their eggs. In their nightly frenzy, they created the strong turbulence that we measured. </p>
<h2>Reviving the ‘biomixing’ controversy</h2>
<p>However, an important question was still unanswered. Were the small but energetic water motions created by the libidinous fish capable of mixing the different ocean layers together? </p>
<p>To answer this question we examined the millimetre-scale temperature signals from our turbulence profiler. We found that the small-scale temperature fluctuations were more than ten times larger during the night, when lively anchovies were around, than during the day. Biological mixing was indeed happening beneath our feet. </p>
<p>We believe that the explanation for our unique finding is related to a fundamental aspect of the physics of turbulence rather than to the sexual preferences of anchovies. </p>
<p>The water column in our study region shows very sharp vertical variations of water properties, referred to as “vertical stratification”. Water layers displaying different properties are thus relatively “thin”, meaning that the small-scale motions created by the fish can mix them together. This contrasts with <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014JC010659">previous studies</a> that have been conducted in more open ocean regions where stratification is usually weaker.</p>
<p>Our fortuitous observation proved the longstanding conjecture of biologically driven mixing of the ocean. However, our finding remains an isolated observation. </p>
<p>There is much work to do to assess the significance of biological mixing for the local ecosystem. But one thing is for sure: the biological mixing controversy will stick around for much longer than we would have expected a few years ago.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<p class="fine-print"><em><span>Bieito Fernandez Castro receives funding from the Natural Environment Research Council, UK. </span></em></p>Anchovies cause a stir as they mate – getting the oceans moving.Bieito Fernandez Castro, Lecturer in Physical Oceanography, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2201062024-01-09T13:25:50Z2024-01-09T13:25:50ZI set out to investigate where silky sharks travel − and by chance documented a shark’s amazing power to regenerate its sabotaged fin<figure><img src="https://images.theconversation.com/files/567867/original/file-20240104-19-fvz9ed.jpg?ixlib=rb-1.1.0&rect=0%2C114%2C919%2C596&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rather than a tracking tag telling scientists where this shark traveled, its violent removal let them observe an unexpected regeneration process.</span> <span class="attribution"><span class="source">Josh Schellenberg</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>I made an accidental and astonishing discovery while studying the movements of sharks off the coast of Jupiter, Florida. I set out to record the migration routes of silky sharks, named for their smooth skin. Instead, in a story filled with twists and turns, I ended up documenting the rare phenomenon of a shark <a href="https://doi.org/10.1155/2023/6639805">regenerating a dorsal fin</a>. </p>
<h2>Tagging, then trauma</h2>
<p>It all started in the summer of 2022, when my team and I tagged silky sharks (<em>Carcharhinus falciformis</em>) as part of my <a href="https://chelsealeighblack.com/research-projects/biotrack/">Ph.D. research</a>. <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-falciformis/">Silky sharks</a> are commonly found in the open ocean and grow to be 10 feet long. Scientists know these sharks congregate in South Florida each summer, but where they go the rest of the year remains a mystery – one I hoped to solve. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three scientists wearing latex gloves lean over the side of a boat holding a still shark. Woman in middle attaches a hand-sized tag with an short antena to the fin on the shark's back." src="https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=493&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=493&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=493&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=620&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=620&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567682/original/file-20240103-23-h8z0ck.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=620&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chelsea Black, center, leads a satellite tagging team from the University of Miami in June 2022.</span>
<span class="attribution"><span class="source">Tanner Mansell</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Local boat captain John Moore took us to a site where sharks are known to gather. We carefully caught and gently attached GPS trackers to the dorsal, or top, fin of 10 silky sharks. </p>
<p>The tags, which are attached like large earrings, do not interfere with swimming and are designed to fall off after a few years. When the tag’s antenna breaks the surface of the water, its GPS location is picked up by overhead satellites, hopefully revealing details of the shark’s secret life.</p>
<p>I headed home to track their travels from my laptop. </p>
<p>The story took an unexpected turn a few weeks later, when I received disturbing photos from an avid diver and underwater photographer, Josh Schellenberg, who knew of my work.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Silky shark swiming in water with its dorsal fin missing a chunk of tissue shaped like a satellite tag." src="https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=333&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=333&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=333&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567714/original/file-20240103-23-9nlx4h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The first sighting of the wounded silky shark in July 2022.</span>
<span class="attribution"><span class="source">Josh Schellenberg</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The photos showed a male silky shark with a large, gaping wound in its dorsal fin, as if someone had taken a satellite-tag-shaped cookie cutter and punched it right through. Josh wondered if this individual was one of the sharks from my study. </p>
<p>When placing the GPS tags, I also place a second tag beneath each shark’s dorsal fin that displays a unique ID number, so I was able to confirm the injured shark was one from my study, #409834.</p>
<p>I felt a mixture of relief and sadness. Relief that the shark survived this ordeal; sadness for the scientific data that would now go uncollected. </p>
<p>Silky sharks are often caught by local fishermen in this area but are protected in Florida and <a href="https://myfwc.com/fishing/saltwater/commercial/sharks/">illegal to kill or retain</a>. Josh’s photos of #409834 showed several hooks in his mouth, so I knew this animal had been captured several times since my team tagged him.</p>
<p>The way the satellite tag attaches means it’s impossible for it to naturally rip out of the fin and leave a wound of this shape. Why someone cut off the shark’s satellite tag remains a mystery, but perhaps they thought they could resell it or possibly wanted to interfere with research. I never expected to see that shark again.</p>
<h2>The return of #409834</h2>
<p>Flash forward to one year later, the summer of 2023. I received several photos of silky sharks from John Moore, our boat captain, who is also an avid diver. John was on the lookout for any of our sharks making their seasonal return to Jupiter. In the many shark photos he sent, I noticed a silky shark with an oddly shaped dorsal fin. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Silky shark swimming through water with an oddly shaped dorsal fin." src="https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567740/original/file-20240103-15-s905sn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Shark #409834 spotted a year later, in June 2023, with a healed dorsal fin.</span>
<span class="attribution"><span class="source">Josh Schellenberg</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>I knew immediately it had to be #409834 from the previous summer. A few days later, John was able to get close enough to photograph the ID tag to confirm my hunch. Josh Schellenberg also spotted and photographed #409834. With both John’s and Josh’s photos, I was able to compare the healed dorsal fin with the freshly injured one. </p>
<p>I wasn’t expecting to make a groundbreaking discovery. Simple curiosity led me to start analyzing the photos. But the revelation was astonishing: Not only had the wound completely healed, but the 2023 dorsal fin was 10.7% larger in size than it was after the injury in 2022. New fin tissue had regenerated.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A collage of four photos – two are close ups of the dorsal fin freshly injured in 2022 and two are close ups of it healed in 2023. Much of it has grown back." src="https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=359&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=359&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=359&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567744/original/file-20240103-29-ocqay6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=451&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Changes in the dorsal fin from 2022 and 2023.</span>
<span class="attribution"><span class="source">Josh Schellenberg and John Moore</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1155/2023/6639805">My analysis</a> determined that within 332 days, the shark regenerated enough tissue that his dorsal fin was almost back to 90% of its original size, growing back more than half of what had been cut off in 2022.</p>
<p>The <a href="https://dlnr.hawaii.gov/sharks/anatomy/fins-swimming/">dorsal fin</a>, pivotal for balance, steering and hydrodynamics, is vital for a shark to be able to hunt and survive. Seeing no infection or any signs of malnourishment in #409834 suggests an extraordinary feat of endurance.</p>
<p>Scientists know that sharks have an incredible <a href="https://doi.org/10.1093/conphys/cov062">aptitude for healing</a> – but mechanisms behind these observations are still poorly understood. While limb regeneration has been widely documented in other marine animals like <a href="https://ssec.si.edu/stemvisions-blog/all-about-starfish">starfish</a> and <a href="https://doi.org/10.1016/j.jembe.2023.151895">crabs</a>, there is only <a href="https://doi.org/10.1093/conphys/coaa120">one other documented case</a> of dorsal fin regeneration in a shark – a whale shark in the Indian Ocean that regrew its dorsal fin after a boat accident in 2006.</p>
<h2>400 million years of resilience</h2>
<p>There’s a reason sharks have been on Earth <a href="https://www.sciencedaily.com/releases/1999/04/990422060147.htm">longer than trees</a> and have survived <a href="https://doi.org/10.1101/2021.01.20.427414">multiple mass extinction events</a> that wiped out other species. They are a product of <a href="https://www.nhm.ac.uk/discover/shark-evolution-a-450-million-year-timeline.html">400 million years</a> of <a href="https://www.floridamuseum.ufl.edu/discover-fish/sharks/fossil/basics/">evolutionary adaptations</a> that demonstrate their remarkable resilience and have primed them for survival.</p>
<p>To be able to pinpoint an ability that helps make them so resilient is a major scientific advance – especially considering scientists are still questioning where silky sharks spend most of their time in the Atlantic. </p>
<p>One person’s attempt to undermine shark science and harm a shark ultimately proved futile. Instead, the shark’s toughness prevailed and led to an amazing discovery about this species. This story also shows there are countless individual people, including scientists like me and shark enthusiasts like Josh and John, who share a genuine love and respect for these animals.</p>
<p>While I’ll never know for certain where #409834 spends the rest of the year, I hope he continues to return to Jupiter each summer so we can further assess his progress. Based on the healing rate calculated in my study, we just might see his dorsal fin grow back to 100% its original size.</p><img src="https://counter.theconversation.com/content/220106/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chelsea Black does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>After scientists’ GPS tracking tag was violently removed from one shark’s dorsal fin, they were in for a surprise: The wound didn’t just heal, but the missing tissue grew back.Chelsea Black, Ph.D. Candidate in Marine Ecosystems and Society, University of MiamiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2091962024-01-08T13:36:16Z2024-01-08T13:36:16ZWhat happens to the ocean if we take out all the fish? A marine ecologist explains the complex roles fish play in their ecosystem<figure><img src="https://images.theconversation.com/files/543088/original/file-20230816-19-h6b36a.jpg?ixlib=rb-1.1.0&rect=6%2C12%2C2038%2C1348&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fish swim in a reef at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/UNBiodiversity/3ead5d56c624402893c0df11ab789657/photo?Query=ocean%20fish&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=262&currentItemNo=31&vs=true">AP Photo/Jacob Asher </a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>What would happen to the ocean if we took out all the fish? – Reny, age 12</strong></p>
</blockquote>
<hr>
<p>The ocean is massive and covers most of the surface of our planet. In addition to its size, it’s packed with life, ranging from an astounding diversity of plants, microbes, worms, corals and crabs to squids, whales and, yes, even fish. The ocean is full of fish, so much so that they make up the <a href="https://doi.org/10.1073/pnas.1711842115">second-largest amount of all carbon</a> – the material that makes up living things – in the entire animal kingdom. They’re just behind the group containing insects and crustaceans.</p>
<p>Most people only interact with the ocean from a beach or in a boat, so it can be hard to wrap your head around how many fish there really are. But the ocean is swarming with them, from its surface <a href="https://www.nbcnews.com/news/world/deepest-ever-fish-filmed-japan-scientists-rcna77858">to its depths</a>. </p>
<p>These fish also come in all kinds of shapes and sizes, ranging from the tiny sardines, guppies and blennies that you might <a href="https://www.palmbeachpost.com/story/opinion/columns/guest/2020/01/25/point-of-view-call-for-more-diversity-not-only-more-fish-in-marine-protected-areas/112150854/">see on a coral reef</a> to massive tunas and whale sharks that you might find <a href="https://www.fisheries.noaa.gov/feature-story/surface-slicks-are-pelagic-nurseries-diverse-ocean-fauna">out in the open ocean</a>. </p>
<p>These fish perform all kinds of <a href="https://doi.org/10.1002/ecs2.4288">roles in their ecosystems</a> that support the lives of other organisms around them. If they disappeared one day, the ocean would look very different.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/542471/original/file-20230813-127481-q0e3vz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542471/original/file-20230813-127481-q0e3vz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542471/original/file-20230813-127481-q0e3vz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542471/original/file-20230813-127481-q0e3vz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542471/original/file-20230813-127481-q0e3vz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542471/original/file-20230813-127481-q0e3vz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542471/original/file-20230813-127481-q0e3vz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">School of slopehead parrotfish.</span>
<span class="attribution"><span class="source">NOAA, Kevin Lino</span></span>
</figcaption>
</figure>
<p>I’m a <a href="https://koryevans.weebly.com/">scientist who studies fish</a>, their diversity and all the ways they contribute to ocean environments.</p>
<h2>Fish as food</h2>
<p>Fish play important roles as both <a href="https://www.noaa.gov/education/resource-collections/marine-life/aquatic-food-webs">predators and prey</a> in ocean ecosystems. Thousands of species throughout the ocean and terrestrial ecosystems rely on fish for food – <a href="https://www.fisheries.noaa.gov/feature-story/economic-importance-seafood">including people</a>. </p>
<p>In coral reef ecosystems, small fish are eaten by larger fish and other marine animals. This means the little fish form the base of the food web – they provide energy to the bigger fish and other creatures. </p>
<figure class="align-center ">
<img alt="Conceptual food web of a coral reef ecosystem identifying key functional groups." src="https://images.theconversation.com/files/542472/original/file-20230813-197557-ebgabl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542472/original/file-20230813-197557-ebgabl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=569&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542472/original/file-20230813-197557-ebgabl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=569&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542472/original/file-20230813-197557-ebgabl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=569&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542472/original/file-20230813-197557-ebgabl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=715&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542472/original/file-20230813-197557-ebgabl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=715&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542472/original/file-20230813-197557-ebgabl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=715&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Links between different species of coral reef animals.</span>
<span class="attribution"><span class="source">Global Change Biology, Rogers et al., 2015</span></span>
</figcaption>
</figure>
<p>Outside of the water, many birds, mammals and reptiles eat fish and rely on them as an <a href="https://doi.org/10.1016/S0921-8009(99)00015-4">essential source of protein</a>. </p>
<p>Even land plants can benefit from the presence of fish. On the western coast of the United States, salmon returning to small streams after spending several years at sea function as a conveyor belt of nutrients. The salmon feed not only animals that catch them, like bears, but also the plants that border the streams. Studies have shown that some plants get <a href="https://www.adfg.alaska.gov/index.cfm?adfg=wildlifenews.view_article&articles_id=407">70% of their nitrogen</a> from salmon that die on or near the river banks. </p>
<p>Humans also depend on fish as a food source. Fish and other seafood products are an important protein source for <a href="https://www.nature.org/en-us/what-we-do/our-priorities/provide-food-and-water-sustainably/food-and-water-stories/global-fisheries/">nearly 3 billion people</a>. Human populations have been eating and following fish around the world for <a href="https://doi.org/10.1073/pnas.1710186114">thousands of years</a>. </p>
<h2>Fish maintain habitats</h2>
<p>Fish are also more than just food. As fish themselves forage for food, they can create and maintain important <a href="https://doi.org/10.1007/s00338-006-0112-y">habitats for other organisms</a>. In coral reef ecosystems, plant-eating fish control the growth of algae by constantly grazing it down. Without the help of these herbivores, or plant-eating fish, the algae would rapidly grow and smother the coral, effectively killing it. </p>
<p>One type of herbivorous fish, the parrotfish, <a href="https://ocean.si.edu/ocean-life/fish/tough-teeth-and-parrotfish-poop">feeds directly on the corals</a>. At first, this may seem bad for the corals, but the grazing done by parrotfish can actually increase a coral colony’s rate of growth. And <a href="https://ocean.si.edu/ocean-life/fish/tough-teeth-and-parrotfish-poop">the poop</a> – yes, the poop – from parrotfish has been shown to be <a href="https://doi.org/10.1016/j.tim.2022.03.006">particularly nutritious</a> for corals. Parrotfish poop also forms part of the <a href="https://ocean.si.edu/ocean-life/fish/tough-teeth-and-parrotfish-poop">beautiful white sand beaches</a> that you may have enjoyed on a family vacation.</p>
<p>Other fish create habitats for other animals and influence their environment by <a href="https://www.ingentaconnect.com/content/umrsmas/bullmar/1986/00000038/00000001/art00006">disturbing sand</a> while they feed. By moving the sand around, they’re exposing tiny organisms hiding in the sand, which other animals can eat. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_pN5-96nduge?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Some fish sift through sand to find their food. That creates more opportunities for other creatures to find food in the sand.</span></figcaption>
</figure>
<p>Despite the fact that many types of fish are confined to the ocean, their presence can be felt across many habitats. They can directly and indirectly affect the lives of the organisms that depend on them for food and shelter. Without fish, Earth would gradually lose its beautiful white sand beaches, the coral reef ecosystems would be overgrown with algae, lots of people would run out of food to eat, and we would lose some of the planet’s most fascinating creatures.</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/209196/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kory Evans receives funding from National Science Foundation. </span></em></p>There are so many fish in the ocean that if you took them out, important habitats and food sources for many creatures would be lost.Kory Evans, Assistant Professor of BioSciences, Rice UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2146882023-12-19T18:13:36Z2023-12-19T18:13:36ZShipwrecks teem with underwater life, from microbes to sharks<figure><img src="https://images.theconversation.com/files/555600/original/file-20231024-25-xo8h4f.jpg?ixlib=rb-1.1.0&rect=30%2C15%2C5061%2C3534&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A school of grunts on a sunken World War II German submarine in the Atlantic Ocean off North Carolina.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/diver-and-schooling-tomtates-on-wwii-u-352-german-royalty-free-image/153943111">Karen Doody/Stocktrek Images via Getty Images</a></span></figcaption></figure><p>Humans have sailed the world’s oceans for thousands of years, but they haven’t all reached port. Researchers estimate that there are <a href="https://unesdoc.unesco.org/ark:/48223/pf0000152883">some three million shipwrecks</a> worldwide, resting in shallow rivers and bays, coastal waters and the deep ocean. Many sank during catastrophes – some during storms or after running aground, others in battle or collisions with other vessels.</p>
<p>Shipwrecks like <a href="https://www.britannica.com/topic/Titanic">the RMS Titanic</a>, <a href="https://www.britannica.com/topic/Lusitania-British-ship">RMS Lusitania</a> and <a href="https://www.britannica.com/technology/monitor-ship-type#ref51448">USS Monitor</a> conjure tales of human courage and sacrifice, sunken treasure and unsolved mysteries. But there’s another angle to their stories that doesn’t feature humans. </p>
<p>I have <a href="https://scholar.google.com/citations?user=wZ-kv2AAAAAJ&hl=en">studied the biology of shipwrecks</a> in the United States and internationally for 14 years. From this work, I have learned that shipwrecks are not only cultural icons but can also be biological treasures that create habitat for diverse communities of underwater life. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/FTYyzAxt3JI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The USS Monitor, which sank off Cape Hatteras, North Carolina, in a storm on Dec. 31, 1862, is now a center for sea life.</span></figcaption>
</figure>
<p>Recently, I led an international team of biologists and archaeologists in disentangling the mysteries of how this transformation happens. Drawing on scientific advances from our team and international colleagues, our <a href="https://academic.oup.com/bioscience/article-lookup/doi/10.1093/biosci/biad084">new study</a> describes how wrecked vessels can have second lives as seabed habitats.</p>
<h2>A new home for underwater life</h2>
<p>Ships are typically made of metal or wood. When a vessel sinks, it adds foreign, artificial structure to the seafloor. </p>
<p>For example, the World War II tanker <a href="https://monitor.noaa.gov/shipwrecks/clark.html">E.M. Clark</a> sank on a relatively flat, sandy seabed in 1942 when it was torpedoed by a German submarine. To this day, the intact metal wreck looms over the North Carolina seafloor like an underwater skyscraper, creating an island oasis in the sand. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Bx_uzNvNU1s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">In this video narrated by NOAA research scientist Avery Paxton, sand tiger sharks hover above the wreck of the E.M. Clark off North Carolina, with vermilion snapper schooling nearby. Jacks and an invasive lionfish also appear.</span></figcaption>
</figure>
<p>The creatures that reside on and around sunken ships are so diverse and abundant that scientists often colloquially call these sites “<a href="https://3d-shipwreck-data-viewer-noaa.hub.arcgis.com/">living shipwrecks</a>.” Marine life ranging from microscopic critters to some of the largest animals in the sea use shipwrecks as homes. Brilliantly colored corals and sponges blanket the wrecks’ surfaces. Silvery schools of baitfish dart and shimmer around the structures, chased by sleek, fast-moving predators. Sharks sometimes cruise around wrecks, likely resting or looking for prey. </p>
<h2>The origin of a second life</h2>
<p>A ship’s transformation from an in-service vessel into a thriving metropolis for marine life can seem like a fairy tale. It has a once-upon-a-time origin story – the wrecking event – and a sequence of life arriving on the sunken structure and beginning to blossom.</p>
<p>Tiny microbes invisible to the naked human eye initially settle on the wreck’s surface, forming a carpet of cells, called a <a href="https://www.britannica.com/science/biofilm">biofilm</a>. This coating helps to <a href="https://doi.org/10.3389/fmars.2019.00048">make the wreck structure suitable</a> for larval animals like sponges and corals to settle and grow there.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Shellfish, deepwater coral and anemones cling to the surface of a sunken wreck." src="https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/555611/original/file-20231024-23-oqeoj2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diverse sea creatures living on the 19th-century, wooden-hulled Ewing Bank wreck, which lies 2,000 feet (610 meters) deep in the Gulf of Mexico.</span>
<span class="attribution"><a class="source" href="https://oceanexplorer.noaa.gov/explorations/19microbial-stowaways/background/archaeology/media/img2-hires.jpg">NOAA</a></span>
</figcaption>
</figure>
<p>Larger animals like fish sometimes appear within minutes after a ship sinks. <a href="https://coastalscience.noaa.gov/news/artificial-reefs-may-help-tropical-fish-expand-geographic-range-video/">Small fish</a> hide in the structure’s cracks and crevices, while <a href="https://doi.org/10.1016/j.fooweb.2020.e00147">large sharks</a> glide around it. <a href="https://doi.org/10.1016/j.marenvres.2020.104916">Sea turtles</a> and marine mammals such as <a href="https://doi.org/10.1371/journal.pone.0130581">fur seals</a> have also been spotted on wrecks.</p>
<h2>Hot spots for biodiversity</h2>
<p>Shipwrecks host quantities and varieties of marine life that can make them hot spots for biodiversity. The microbes that transform the wreck structure into habitat also enrich the surrounding sand. Evidence from deep Gulf of Mexico wrecks shows that a <a href="https://doi.org/10.1038/s41396-021-00978-y">halo of increased microbial diversity</a> radiates outward anywhere from 650 to 1,000 feet (200-300 meters) from the wreck. In the Atlantic Ocean, <a href="https://doi.org/10.1111/faf.12548">thousands of grouper</a>, a type of reef fish highly valued by fishers, congregate around and inside shipwrecks.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Fish hover above a wrecked ship's surface." src="https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/555613/original/file-20231024-29-aaqe3w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Groupers and a conger eel, bottom center, on the wreck of the German submarine U-576 off the coast of North Carolina.</span>
<span class="attribution"><a class="source" href="https://oceanexplorer.noaa.gov/explorations/16battlefield/logs/sept7/sept7.html">NOAA</a></span>
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<p>Shipwrecks can also serve as stepping stones across the ocean floor that animals use as temporary homes while moving from one location to another. This has been documented in areas of the world with dense concentrations of shipwrecks, such as off North Carolina, where storms and war have sunk hundreds of ships.</p>
<p>In this part of the ocean, popularly known as the “<a href="https://www.ncpedia.org/graveyard-atlantic">Graveyard of the Atlantic</a>,” reef fish likely <a href="https://doi.org/10.1038/s42003-019-0398-2">use the islandlike shipwrecks as corridors</a> when moving north or south away from the equator to find favorable water temperatures as climate change <a href="https://theconversation.com/ocean-heat-is-at-record-levels-with-major-consequences-174760">warms the oceans</a>. Scientists have also observed <a href="https://doi.org/10.1002/ecy.2687">sand tiger sharks</a> traveling from one wreck to another, possibly using the shipwrecks like rest stops during migration.</p>
<p>In the deep sea, life growing on shipwrecks can even generate energy. Tube worms that grow on organic shipwreck materials such as paper, cotton and wood host symbiotic bacteria that produce chemical energy. Such tube worm colonies have been documented in the Gulf of Mexico on the steel <a href="https://www.boem.gov/sites/default/files/boem-newsroom/Library/Ocean-Science/Ocean-Science-Jul-Aug-Sep-2014.pdf">luxury yacht Anona</a>. </p>
<h2>Biological mysteries abound</h2>
<p>Despite their biological value, shipwrecks can also threaten underwater life by altering or destroying natural habitats, causing pollution and spreading invasive species.</p>
<p>When a ship sinks, it can damage existing seafloor habitats. In a well-documented case in the Line Islands of the central Pacific, an <a href="https://doi.org/10.1038/ismej.2011.114">iron shipwreck</a> sank on a healthy coral reef. The iron infusion substantially decreased coral cover, and the reef was overcome by algae.</p>
<p>Ships may carry pollutants as fuel or cargo. As shipwrecks deteriorate in seawater, there is a risk that these pollutants may be released. The <a href="https://doi.org/10.1016/j.marpolbul.2021.112087">level of risk</a> depends on how much of the pollutant the ship was carrying and how intact the wreck is. One recent investigation revealed that effects from shipwreck pollutants can be detected in microbes up to <a href="https://doi.org/10.3389/fmars.2022.1017136">80 years after the wreck</a>.</p>
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<figcaption><span class="caption">Ships and planes wrecked in wartime can leak toxic materials for decades after they come to rest in the ocean.</span></figcaption>
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<p>Shipwrecks may also inadvertently assist the spread of invasive plants and animals that wreak biological havoc. Wrecks are new structures that invasive species can settle on, grow and use as a hub to expand to other habitats. <a href="https://doi.org/10.1016/j.marpolbul.2020.111394">Invasive cup coral</a> has spread on World War II shipwrecks off Brazil. In Palmyra Atoll in the Pacific, a type of anemone called a corallimorph <a href="https://doi.org/10.1371/journal.pone.0002989">rapidly invaded</a> a shipwreck and now <a href="https://doi.org/10.1007/s10530-018-1696-1">threatens healthy coral reefs</a>.</p>
<h2>The future of shipwreck exploration</h2>
<p>Shipwrecks create millions of study sites that scientists can use to ask questions about marine life and habitats. One of the greatest challenges is that many wrecks are undiscovered or in remote locations. Advances in technology can help researchers see into the most inaccessible areas of the ocean, not only to find shipwrecks but to better understand their biology. </p>
<p>Maximizing discovery will require biologists, archaeologists and engineers to work together to explore these special habitats. Ultimately, the more we learn, the more effectively we can conserve these historical and biological gems.</p><img src="https://counter.theconversation.com/content/214688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Avery Paxton is affiliated with NOAA National Centers for Coastal Ocean Science. </span></em></p>When ships sink, they add artificial structures to the seafloor that can quickly become diverse, ecologically important underwater communities.Avery Paxton, Research Marine Biologist, National Oceanic and Atmospheric AdministrationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2174282023-12-14T22:14:08Z2023-12-14T22:14:08ZClimate change is further reducing fish stocks with worrisome implications for global food supplies<figure><img src="https://images.theconversation.com/files/565799/original/file-20231214-17-9k9tr0.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4000%2C3000&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Seafood is a ubiquitous human food-source, the future stability of which is uncertain.</span> <span class="attribution"><span class="source">(Pexels)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/climate-change-is-further-reducing-fish-stocks-with-worrisome-implications-for-global-food-supplies" width="100%" height="400"></iframe>
<p>The health benefits of eating seafood are appreciated in many <a href="https://www.fao.org/3/cc0461en/online/sofia/2022/consumption-of-aquatic-foods.html">cultures</a> which rely upon it to provide critical nutrients vital to our <a href="https://doi.org/10.1016/bs.afnr.2021.04.001">physical and mental development and health</a>. Eating fish and shellfish provides significant benefits to <a href="https://doi.org/10.1038/nrn3820">neurological development and functioning</a> and provides protection against the risks of <a href="https://doi.org/10.1038/s43016-019-0013-1">coronary heart disease and Type 2 diabetes</a>. </p>
<p>Over three billion people get at least 20 per cent of their daily animal protein from fish. In countries from Bangladesh to Cambodia, Gambia, Ghana, Indonesia, Sierra Leone and Sri Lanka, <a href="https://www.fao.org/3/ca9229en/ca9229en.pdf">fish consumption accounts for 50 per cent or more</a> of daily intake.</p>
<p>However, expansive growth of human populations globally puts immense pressure on the health of wild fish stocks. Fish catches <a href="https://doi.org/10.1038/ncomms10244">peaked in 1996</a>, and <a href="https://www.fao.org/state-of-fisheries-aquaculture">one-third are considered overexploited</a>. With less fish available to still more people, the future of fish as an accessible source of nutritious food is at risk, particularly among low-income countries.</p>
<h2>Seafood nutrient losses</h2>
<p>Threats to seafood access aren’t just due to overharvesting. There is a growing body of research showing that higher water temperatures due to climate change can impact the <a href="https://doi.org/10.1038/nature12156">presence and abundance of the catch</a>, through shifts in species distribution and changes in the species caught. This impacts the amount that can be harvested, as well as the nutritional value of that harvest.</p>
<p>A <a href="https://doi.org/10.1038/s41558-023-01822-1">new study</a> (which Aaron MacNeil contributed to) quantified nutrient availability from seafood through time considering the twin impacts of overfishing and climate change. </p>
<p>Focusing on four key nutrients important to human health — calcium, iron, omega-3 fatty acids and protein — the authors argue that nutrient availability in seafood has been declining since 1990 and will further decline by around 30 per cent by 2100 in predominately tropical, low-income countries with 4 C of warming.</p>
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Read more:
<a href="https://theconversation.com/how-climate-change-induced-stress-is-altering-fish-hormones-with-huge-repercussions-for-reproduction-213140">How climate change-induced stress is altering fish hormones — with huge repercussions for reproduction</a>
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<p>These predicted losses are significant. While global famines are now relatively rare, some <a href="https://doi.org/10.1016/j.gfs.2020.100480">50 million people suffer from “hidden hunger”</a> — nutrient-deficient diets that are masked by being otherwise calorie-sufficient. </p>
<p>For animal-derived nutrients such as B12 and omega-3 fatty acids, <a href="https://doi.org/10.1038/534317a">nearly 20 per cent of the global population are at risk of becoming nutrient-deficient</a> in coming decades due to reliance on wild-caught fish.</p>
<p>Climate change is also affecting natural cycles of nutrients in the ocean. For example, it has been predicted that increasing water temperatures will cause a <a href="https://doi.org/10.1007/s13280-019-01234-6">decline in natural omega-3 availability from seafood by more than 50 per cent by 2100</a>. At the bottom of the food chain, microalgae that naturally produce omega-3s <a href="https://doi.org/10.1111/gcb.13295">are less productive at warmer temperatures</a> and this cascades through marine and freshwater food chains resulting in fish having less omega-3s available to eat and store in their bodies. </p>
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<img alt="Men standing on three small boats cast nets into the ocean." src="https://images.theconversation.com/files/565818/original/file-20231214-15-s4v8j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565818/original/file-20231214-15-s4v8j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565818/original/file-20231214-15-s4v8j4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565818/original/file-20231214-15-s4v8j4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565818/original/file-20231214-15-s4v8j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565818/original/file-20231214-15-s4v8j4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565818/original/file-20231214-15-s4v8j4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The global problems of climate change and overfishing have led to decreasing availability of seafood for millions around the world.</span>
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<p>These kinds of climate-caused losses are expected to disproportionately affect vulnerable populations, especially in inland Africa.</p>
<h2>Challenges and strategies for nutritious seafood</h2>
<p>Aquaculture can help supply some of these missing nutrients, but it is an industry also vulnerable to the effects of climate change. A <a href="https://doi.org/10.3389/fsufs.2021.609097">recent study</a> predicted that 90 per cent of aquaculture will be impacted by climate change, where warm waters increase <a href="https://www.jstor.org/stable/26920865">disease outbreaks, harmful algal blooms and impact the availability of feed supplies</a>.</p>
<p><a href="https://www.un.org/en/global-issues/food">Global disparities already exist in food security</a> that will be exacerbated by climate change in the future. Yet the effects of warming waters on nutrient availability from seafood will compound these inequities among tropical and low-income countries. </p>
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<a href="https://theconversation.com/the-future-of-fishing-and-fish-and-the-health-of-the-ocean-hinges-on-economics-and-the-idea-of-infinity-fish-182749">The future of fishing and fish — and the health of the ocean — hinges on economics and the idea of 'infinity fish'</a>
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<p>These results suggest a major challenge to our future nutritional security that demands strong fisheries and aquaculture management to facilitate equitable distribution of nutritious seafoods. </p>
<p>Improvements are possible. </p>
<p>For example, <a href="https://doi.org/10.1038/s41586-019-1592-6">redirecting nine per cent of Namibia’s fisheries toward its coastal population</a> would alleviate the severe iron deficiencies experienced there. Policies that prioritize nutrient supply would help maintain diets as the climate warms. </p>
<p>The recent United Nations call to action for <a href="https://www.fao.org/documents/card/en?details=cc0459en/">blue transformation</a> emphasizes the need to provide sufficient aquatic food from fisheries and aquaculture for our growing population in a sustainable way. </p>
<p>To do this, strategies are needed to achieve healthy, equitable and resilient food systems that adequately deal with overfishing, strive for equal access to resources and markets and mitigate the environmental impacts of aquatic food production. </p>
<p>Ultimately, these strategies must support the nutritional security of vulnerable nations and consider global health equity and the cultural significance of seafood.</p><img src="https://counter.theconversation.com/content/217428/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stefanie Colombo receives funding from the Natural Sciences and Engineering Research Council and the Ocean Frontier Institute, through an award from the Canada First Research Excellence Fund. She serves as the Science Advisor for the Aquaculture Association of Nova Scotia. </span></em></p><p class="fine-print"><em><span>Aaron MacNeil receives funding from the Shark Conservation Fund, the Natural Sciences and Engineering Research Council, and the Ocean Frontier Institute, through an award from the Canada First Research Excellence Fund.</span></em></p>Climate change and overfishing are depleting global fish stocks with clear implications for the food security future of billions of people.Stefanie Colombo, Canada Research Chair in Aquaculture Nutrition, Dalhousie UniversityAaron MacNeil, Professor, Department of Biology, Dalhousie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2166992023-11-27T11:34:01Z2023-11-27T11:34:01ZStones inside fish ears mark time like tree rings – and now they’re helping us learn about climate change<figure><img src="https://images.theconversation.com/files/556852/original/file-20231031-23-62b3ms.jpg?ixlib=rb-1.1.0&rect=44%2C35%2C5939%2C3956&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/large-atlantic-bluefin-tuna-common-tunny-2190003345">Dolores M. Harvey/Shutterstock</a></span></figcaption></figure><p>As a marine biologist, I’ve always found it fascinating to learn about how animals adapt to their habitat. But climate change has made it more important than ever – wild animals’ futures may depend on how much we understand about them. </p>
<p>Fish have a kind of stone in their ear that scientists can read like tree rings. My team’s <a href="https://www.nature.com/articles/s41467-023-41930-2">new research</a> found a way to decode the chemicals in these stones to measure how much energy they used when alive. What we learned could help bluefin tuna survive the climate crisis.</p>
<p>There is still so much <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.13467">we don’t know</a> about how animals respond when their habitat suddenly changes. Temperature is one of the most important puzzle pieces, as it <a href="https://www.sciencedirect.com/science/article/abs/pii/B9780123745538001593">affects the rates of the chemical reactions that define life</a>. </p>
<p>For animals, rising temperatures act like inflation. Rising prices mean housing and food take up more of our budget, leaving less money for luxuries. More heat means more of an animal’s bodily resources, like food and oxygen, are needed to <a href="https://www.sciencedirect.com/science/article/abs/pii/B9780123745538001970">fuel basic functions</a>, like breathing and moving, leaving less energy for growth and reproduction.</p>
<p>However, heat changes don’t <a href="https://www.cefas.co.uk/news-and-resources/news/new-research-identifies-winners-and-losers-of-future-climate-change-on-uk-fish-species/">affect all animals the same way</a>. Just as the wealthy can use their large cash reserves to weather inflation, animals differ in how close they are to their energy “ceiling”.</p>
<h2>Warming waters</h2>
<p>Animals living in temperatures in the middle of their species’ range can increase the rate of their metabolism, meeting the extra cost of living in warmer waters. Those on the warm edge of their species’ range might be closer to their limits, where increases in temperature push them into a form of energy debt. </p>
<p>Reserves that might have been used for growth must be diverted to maintain essential life processes. <a href="https://www.science.org/doi/10.1126/science.abo4259">Rising temperatures</a>, through their effects on metabolism, force species to adapt, move somewhere new or die. </p>
<p>Measuring energy expenditure in wild animals is <a href="https://www.sciencedirect.com/science/article/abs/pii/S109564331630099X">no easy task</a>. Fortunately, metabolic reactions leave chemical traces in the body. </p>
<p>The <a href="https://uni.hi.is/scampana/otoliths">otolith</a> is a stony lump in the fish ear. Otolith rings, much like tree rings, reveal a fishs’s age. At the University of Southampton we have developed a technique to decode the chemistry of otoliths. </p>
<p>Different forms or isotopes of oxygen in the otolith indicate the temperature the fish experienced when it was alive. Carbon isotopes reveal <a href="https://www.nature.com/articles/s42003-018-0266-5">how quickly food was converted</a> into energy. Fish carry their fitness trackers in their ears.</p>
<p>Studying how animals’ energy needs shift with temperature can help us predict which animals are most at risk from rising temperatures. Juveniles, for instance, which need to grow quickly so they are strong enough to evade predators, might be more vulnerable to the effects of global warming. </p>
<p>Recently, we applied this new technique to <a href="https://www.worldwildlife.org/species/bluefin-tuna">Atlantic bluefin tuna</a>. These fish can grow to two metres long and can swim at 40mph. They also have a high metabolism which allows them to thrive in colder waters than most other tuna species. </p>
<p><a href="https://www.msc.org/species/tuna/recent-history-of-bluefin-tuna">Overfishing in the 20th century</a> made Atlantic bluefin tuna populations crash. Fish management policies have allowed bluefin tuna populations in the north Atlantic to recover, and shoals of bluefin are <a href="https://www.mcsuk.org/news/bluefin-tuna-an-ocean-giant-on-the-rise/#:%7E:text=Within%20three%20years%2C%20numbers%20of,Isles%20of%20Scilly%2C%20and%20Ireland">once again regular visitors</a> to waters around the British Isles and northern Europe. </p>
<p>Bluefin tuna spawn in <a href="https://www.pewtrusts.org/-/media/legacy/uploadedfiles/peg/publications/fact_sheet/atlantic20bluefin20spawning20englishpdf.pdf">both the western and eastern sides</a> of the Atlantic. But these two spawning populations show different rates of recovery. </p>
<p>The proportion of adult fish with a western (Gulf of Mexico) origin has declined over time. Proportionally more eastern (Mediterranean) origin fish are surviving to adulthood each year. </p>
<p>Our study asked whether these differences in recovery can be explained by temperature. We discovered that the metabolic rates for young tuna peak at around 28°C. Tuna in warmer waters had lower metabolic rates, showing that their bodies were unable to keep up with the energy costs of living in temperatures over 28°C. </p>
<p>In the spawning and nursery grounds of the Gulf of Mexico, temperatures often surpass 28°C. While it has always warmer been in the Gulf of Mexico than the Mediterranean Sea, recent warming means that the area of suitable habitat below the 28°C threshold has become smaller and smaller. Sea temperatures in Florida exceeded 36°C in June 2023.</p>
<p>Slow recovery in western tuna populations could be attributed to these warm water conditions and its effect on growth of juvenile tuna. In contrast, most of the Mediterranean currently remains below 28°C during summer.</p>
<h2>Looking ahead</h2>
<p>The recent recovery of bluefin tuna may not last. We used climate models to predict how quickly ocean warming will start to affect juvenile tuna.</p>
<p>Even middle-of-the-road projections suggest that the eastern half of the Mediterranean Sea will cross the 28°C threshold within 50 years. In the last two years we have seen <a href="https://www.euronews.com/green/2023/08/04/ocean-heat-record-broken-and-experts-fear-temperatures-could-rise-even-further">record average temperatures</a> in <a href="http://www.ceam.es/ceamet/SST/SST-trend.html">the Mediterranean</a> already approaching the 28°C threshold. </p>
<p>We need a long-term solution to protect tuna. </p>
<p>As the oceans continue to warm, tuna may establish new spawning and nursery areas in regions that were previously too cold, for instance further north on the US’s eastern coastline. If so, juvenile tuna would be in danger of getting caught unintentionally by fisheries, also known as bycatch, </p>
<p>Bluefin tuna are a sought-after delicacy for sushi in Asia where a single fish <a href="https://www.theatlantic.com/international/archive/2014/01/sushinomics-how-bluefin-tuna-became-a-million-dollar-fish/282826/">can sell for over a million dollars</a>. But they are more than culinary delicacies. Tuna fish are giving us a warning of the challenges that lie ahead for marine wildlife. </p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Clive Trueman receives funding from UKRI. </span></em></p>My team studied bluefin tuna otoliths to learn why some populations are recovering faster than others.Clive Trueman, Professor of Marine Biology, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2162542023-11-14T13:25:27Z2023-11-14T13:25:27ZPFAS ‘forever chemicals’ are getting into ocean ecosystems, where dolphins, fish and manatees dine – we traced their origins<p>PFAS, the “forever chemicals” that have been raising health concerns across the country, are not just a problem in drinking water. As these chemicals leach out of <a href="https://doi.org/10.1016/j.scitotenv.2015.12.081">failing septic systems</a> and <a href="https://doi.org/10.1016/j.watres.2021.117983">landfills</a> and wash off <a href="https://doi.org/10.1016/j.scitotenv.2021.150393">airport runways</a> and <a href="https://doi.org/10.1016/j.jhazmat.2022.129264">farm fields</a>, they can end up in streams that ultimately discharge into ocean ecosystems where fish, dolphins, manatees, sharks and other marine species live.</p>
<p>We study the risks from these persistent pollutants in coastal environments as <a href="https://scholar.google.com/citations?user=z697KEMAAAAJ&hl=en">environmental</a> <a href="https://scholar.google.com/citations?user=w3It4CgAAAAJ&hl=en">analytical chemists</a> at Florida International University’s Institute of the Environment.</p>
<p>Because PFAS can <a href="https://doi.org/10.1016/j.envint.2022.107640">enter the food chain</a> and accumulate in marine plants and animals, including fish that humans eat, the spread of these chemicals has <a href="https://doi.org/10.1016/j.envres.2022.115165">ecological</a> and <a href="https://doi.org/10.1016/j.scitotenv.2022.155316">human health</a> implications. </p>
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<img alt="Reef fish in Biscayne Bay." src="https://images.theconversation.com/files/558906/original/file-20231111-17-ata3gl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558906/original/file-20231111-17-ata3gl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558906/original/file-20231111-17-ata3gl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558906/original/file-20231111-17-ata3gl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558906/original/file-20231111-17-ata3gl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558906/original/file-20231111-17-ata3gl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558906/original/file-20231111-17-ata3gl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Biscayne Bay and nearby coastal areas are teeming with fish, including many varieties that people eat.</span>
<span class="attribution"><a class="source" href="https://www.nps.gov/media/photo/gallery-item.htm?pg=898241&id=ccce1eac-1dd8-b71b-0bc0-d80f536c707c&gid=CA49F0A1-1DD8-B71B-0B6B1F1948BFA884">NPS image by Shaun Wolfe</a></span>
</figcaption>
</figure>
<p>In a new study, we <a href="https://doi.org/10.1016/j.scitotenv.2023.168413">traced the origins of PFAS contamination</a> in Miami’s <a href="https://doi.org/10.1007/s11356-022-21589-w">Biscayne Bay</a> to help pinpoint ways to reduce the harm.</p>
<h2>What are PFAS?</h2>
<p>PFAS – perfluoroalkyl and polyfluoroalkyl substances – are a group of human-made contaminants that have been <a href="https://theconversation.com/what-are-pfas-the-forever-chemicals-showing-up-in-drinking-water-an-environmental-health-scientist-explains-185015">used for over 50 years</a>. They’re found in personal care products, such as cosmetics and shampoo, and in water-repellent coatings for nonstick cookware and food packaging. They’re also used in adhesives and aqueous firefighting foams, among other products.</p>
<p>As those PFAS-containing products washed down drains and were thrown in landfills over the years, PFAS chemicals became widespread in the environment. Eventually, these chemicals found their way into aquatic ecosystems, including surface water, groundwater and coastal environments.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=534&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=534&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558904/original/file-20231111-15-iq9oxm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=534&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An illustration shows some of the sources of PFAS in the environment.</span>
<span class="attribution"><a class="source" href="https://scdhec.gov/environment/polyfluoroalkyl-substances-pfas">North Carolina Department of Health and Environmental Control</a></span>
</figcaption>
</figure>
<p>The same stability and resistance to degrading that makes these chemicals valuable for water- and stain-proof products also makes them nearly impossible to destroy. Hence, the nickname “forever chemicals.” They persist in the environment for decades to centuries.</p>
<p>That’s a problem, because PFAS have been linked to <a href="https://doi.org/10.1038/s41370-018-0097-y">immunological disorders</a>, endocrine, developmental, reproductive and neurological disruption and increased risk of bladder, <a href="https://doi.org/10.1007/s00204-020-02808-0">liver</a>, <a href="https://doi.org/10.1093/jnci/djaa143">kidney</a> and <a href="https://doi.org/10.1289/EHP12603">testicular cancer</a>. A drinking water study by the U.S. Geological Survey estimated these chemicals were in <a href="https://www.usgs.gov/news/national-news-release/tap-water-study-detects-pfas-forever-chemicals-across-us">at least 45% of tap water</a> across the U.S., and a large percentage of Americans are now believed to have <a href="https://www.niehs.nih.gov/health/topics/agents/pfc/index.cfm">PFAS detectable in their blood</a>.</p>
<p>Studies have also found PFAS in a broad range of <a href="https://doi.org/10.1016/j.envint.2022.107640">marine wildlife</a>, including in the livers of otters and in gulls’ eggs, as well as <a href="https://doi.org/10.1016/j.envres.2022.115165">in freshwater fish</a> across the U.S. These chemicals have already been shown to affect the <a href="https://doi.org/10.1016/j.envint.2019.105358">immune system and liver function of fish</a> and <a href="https://doi.org/10.1016/j.envint.2015.10.007">marine mammals</a>.</p>
<h2>How PFAS get into the marine environment</h2>
<p>When we began tracking the sources of PFAS in Biscayne Bay, we found hot spots of these chemicals around the exits of urban canals – especially the Miami River, Little River and Biscayne Canal. Each of these canals, we found, is a <a href="https://doi.org/10.1016/j.scitotenv.2023.168413">major point source</a> contributing to the presence of PFAS in offshore areas of the Atlantic Ocean.</p>
<p>One major source of that PFAS is sewage contamination from failed septic systems and wastewater leaks in urban areas. This is evident by the presence of the types of PFAS – such as PFOS, PFOA, PFPeA, PFHxS, PFHxA, PFBA and PFBS – that <a href="https://cfpub.epa.gov/ncea/iris_drafts/recordisplay.cfm?deid=345065">are used as</a> stain and grease repellents and in carpets, food packaging materials and household products.</p>
<p>Another major source is represented by the predominance of <a href="https://doi.org/10.1093/toxsci/kfad006">6-2 FTS</a> in the Miami River – 6-2 FTS is a fluorotelomer PFAS typically used in aqueous film-forming foam found at military and airport facilities. The Miami River flows past rail yards, industries and Miami International Airport on its way to Biscayne Bay.</p>
<figure class="align-center ">
<img alt="A map of Miami's Biscayne Bay and nearby coastal areas that were sampled. The hot spots stand out clearly near canal exits." src="https://images.theconversation.com/files/558902/original/file-20231111-17-le8qtk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558902/original/file-20231111-17-le8qtk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=847&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558902/original/file-20231111-17-le8qtk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=847&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558902/original/file-20231111-17-le8qtk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=847&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558902/original/file-20231111-17-le8qtk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1065&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558902/original/file-20231111-17-le8qtk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1065&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558902/original/file-20231111-17-le8qtk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1065&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A map from the study shows PFAS hot spots near canals that carry water from the city. Red indicates higher PFAS concentrations, measured in nanograms per liter. Green indicates lower, more diluted PFAS concentrations.</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We also used a model to predict how ocean currents would disperse PFAS coming out of those canals and into coastal areas. We found that the PFAS concentrations were highest close to the canals, decreased along the bay and declined as ocean water became deeper and more saline, which makes PFAS less soluble in water. </p>
<p>Overall, PFAS concentrations were almost <a href="https://doi.org/10.1016/j.scitotenv.2023.168413">six times higher</a> in surface waters near land compared with deep-water samples collected 13 to 33 feet (4 to 10 meters) below the surface in the bay and offshore. That suggests the highest risk is to pelagic fish that hang out in surface waters, such as mackerel, tunas and mahi-mahi.</p>
<h2>How marine organisms are at risk</h2>
<p>The <a href="https://doi.org/10.1016/j.scitotenv.2023.168413">levels of PFOS and PFOA</a> in our study were below the Florida Department of Environmental Protection advisory levels in surface water for human health exposure. However, the advisory levels might not be protective of human and marine life. </p>
<p>They do not take into consideration that these chemicals accumulate <a href="https://doi.org/10.1016/j.jhazmat.2022.128602">through the food chain</a>. Higher concentration in the top of the food web means PFAS could pose a greater <a href="https://doi.org/10.1016/j.chemosphere.2009.07.079">risk to dolphins</a>, sharks and humans <a href="https://doi.org/10.1021/acs.est.3c00374">that consume fish</a>.</p>
<figure class="align-center ">
<img alt="A man leans over the edge of a boat holding a rope attached to sampling devices that are in the water below." src="https://images.theconversation.com/files/558903/original/file-20231111-21-a6fbtm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558903/original/file-20231111-21-a6fbtm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=457&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558903/original/file-20231111-21-a6fbtm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=457&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558903/original/file-20231111-21-a6fbtm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=457&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558903/original/file-20231111-21-a6fbtm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=574&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558903/original/file-20231111-21-a6fbtm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=574&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558903/original/file-20231111-21-a6fbtm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=574&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Olutobi Daniel Ogunbiyi, an author of this article and lead author of the study, takes water samples in Biscayne Bay.</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Many types of PFAS identified in our samples are not regulated, and their potential toxicity is unknown. We believe there is a need for federal and state agencies to develop guidelines and implement action plans to protect people and the aquatic life in Biscayne Bay.</p>
<h2>What you can do about it</h2>
<p>Given the persistence of PFAS and their widespread use, it is not surprising that these forever chemicals are found in almost all water systems in South Florida and are showing up <a href="https://doi.org/10.1016/j.scitotenv.2020.143297">in coastal waters around the world</a>.</p>
<p>While scientists look for effective and efficient ways to eliminate and remove these chemicals from water, food and the environment, people can limit their use of PFAS-containing products to reduce the amounts of these chemicals that get into the marine environment.</p>
<p>Here are some <a href="https://www.fda.gov/food/process-contaminants-food/authorized-uses-pfas-food-contact-applications">common products that contain PFAS</a> to watch for: Teflon nonstick cookware; food packaging for fast food and popcorn; water-resistant clothing and cosmetics; and treated carpets.</p><img src="https://counter.theconversation.com/content/216254/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natalia Soares Quinete receives funding from National Science Foundation.</span></em></p><p class="fine-print"><em><span>Olutobi Daniel Ogunbiyi receives funding from the National Science Foundation awarded through FIU Institute of Environment and Center for Research and Excellence in Science and Tech. </span></em></p>Scientists found PFAS hot spots in Miami’s Biscayne Bay where the chemicals are entering coastal waters and reaching the ocean. Water samples point to some specific sources.Natalia Soares Quinete, Assistant Professor of Chemistry, Florida International UniversityOlutobi Daniel Ogunbiyi, Ph.D. Candidate in Chemistry, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2170252023-11-13T21:44:00Z2023-11-13T21:44:00ZGulf of St. Lawrence: Analyzing fish blood can show us how healthy they are<figure><img src="https://images.theconversation.com/files/557461/original/file-20231003-21-bibw4p.jpeg?ixlib=rb-1.1.0&rect=30%2C12%2C3995%2C3005&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The industrialization of the fishing industry and changes in the environment have raised many issues about the management of our fisheries.</span> <span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span></figcaption></figure><p>The Gulf of St. Lawrence is an invaluable resource for Canada. Fish and shellfish fisheries that date to the 16th century have remained an essential source of income for many communities, including those on the North Shore and Gaspésie or the Îles-de-la-Madeleine.</p>
<p>For example, in <a href="https://publications.gc.ca/collections/collection_2019/mpo-dfo/Fs124-10-2018-eng.pdf">Îles-de-la-Madeleine</a>, nearly 1,800 jobs (for a total of 12,500 inhabitants) were linked to fishing in 2015.</p>
<p>But the industrialization of fishing, and changes in the environment, have brought about many new problems in the management of our fisheries. The abundance of different fish species in the Gulf has fluctuated greatly over the last 20 years.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
</figcaption>
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<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
<hr>
<p>A case in point: the number of Greenland halibut has declined drastically. This year, <a href="https://www.hi.no/hi/nettrapporter/imr-pinro-en-2023-6">landings</a> are six times lower for fishermen compared to last year.</p>
<p>But other species are benefiting from the situation. This is the case for the population of Atlantic halibut, which is at record levels today.</p>
<p>What is causing these changes? And can we predict further changes?</p>
<p>As a doctoral student in biology at the Institut national de la recherche scientifique (INRS), I am trying to find possible answers to these questions as part of my research work.</p>
<h2>A new health monitoring technique</h2>
<p>The means available for studying the health of fish at the individual level are limited. On the one hand, we can calculate indicators from the weight and height of individual fish. But these measurements are too vague and don’t tell us much.</p>
<p>The logistics of performing biopsies on the tissue of fish — which requires taking samples from their muscle or organs — are complex. To carry them out, researchers must have to travel to the ocean, physically collect samples and bring them back to a laboratory. And then there are ethical considerations, since obviously fish must be sacrificed to achieve this.</p>
<p>Even so, these methods are not very effective for detecting stress induced by environmental changes, and are not effective for detecting stress at early stages, before the physical effects can become manifest.</p>
<p>Yet in a context where the abundance of certain fish species is in rapid decline, an analysis of their overall health is necessary. Fortunately, a new tool is being developed: the <a href="https://www.nature.com/articles/s41598-023-32690-6">circulating microbiome</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="viruses in the blood" src="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It is often wrongly believed that blood is sterile.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>A little-known practice</h2>
<p>The circulating microbiome is a biomarker, an alarm signal that can be detected in fish even before their health begins to deteriorate. A good biomarker is sensitive, easy to sample, and inexpensive.</p>
<p>The analysis of the circulating microbiome, made up of the DNA of bacteria found in the blood, is directly inspired by <a href="https://theconversation.com/ladn-%20circulating-a-new-simple-and-rapid-weapon-in-the-diagnosis-and-monitoring-of-cancers-206786">similar analyses performed on humans</a>, which provide a great deal of information.</p>
<p>In particular, these analyses make it possible to detect anomalies resulting from the effect of a stress factor on the body, or the development of a disease.</p>
<p>Changes in the environment can also be detected from studying the circulating microbiome. But a major problem emerges here: a fish is not a human. Humans are studied in such detail that knowledge about their health can then be used for an infinite amount of further research. However, sampling fish blood is not a common practice. So there is a great deal that needs to be done before we can properly evaluate the health of fish.</p>
<p>Since the analysis of the circulating microbiome in fish has never been studied before, a lot of work needs to be done to develop the technique.</p>
<h2>Traces of bacteria in the blood?</h2>
<p>As blood circulates throughout the body, it comes into contact specifically with bacteria that make up the other microbiomes (intestinal, oral, dermal). Both in fish and humans, these bacteria are essential for good health.</p>
<p>When we analyze bacterial DNA in the blood, it is therefore possible to find bacteria from the intestine, mouth, or skin. But the hypothesis that these are bacteria specific to the blood cannot be completely ruled out either.</p>
<p>While some continue to believe that blood is sterile, and therefore does not contain any bacteria, we have known since the 1970s that this hypothesis is false — it was confirmed <a href="https://doi.org/10.1128/jcm.39.5.1956-1959.2001">in the 2000s by genomic studies</a>. It’s possible that in 1674, the Dutch microbiologist Antonie Van Leeuwenhoek may even have observed bacteria in salmon blood <a href="https://doi.org/10.3389/fcimb.2019.00148">under a microscope</a>.</p>
<p>Today, we can analyze these bacteria in detail by targeting a very specific bacterial gene, the 16S ribosomal RNA gene. Present in all bacteria around the world, this gene varies slightly from one species to another. That makes it possible to identify and analyze the biodiversity of the microbiome.</p>
<h2>I eat, therefore I am</h2>
<p>Our recent work has made it possible to characterize, for the first time, the <a href="https://www.nature.com/articles/s41598-023-32690-6">circulating microbiomes of turbot and halibut</a>. We have demonstrated that the two fish species have circulating microbiomes dominated by the presence of the species <em>Pseudoalteromonas</em> and <em>Psychrobacter</em>. These bacteria are known to colonize cold environments, for example the bottom of the Gulf of St. Lawrence, which is around 5°C. They are also known to produce bioactive compounds (antibacterials and antifungals). They are more tenacious than other bacteria.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person with blue gloves holds a fish" src="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Greenland halibut.</span>
<span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span>
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</figure>
<p>However, differences can be observed between the two species. Turbot has more bacteria called <em>Vibrio</em>, some of which metabolize chitin, a molecule that makes up the shells of the invertebrates on which it feeds. Atlantic halibut, for its part, presents more <em>Acinetobacter</em> bacteria, typical of piscivorous (fish-eating) diets in the intestinal microbiomes. The circulating microbiome in these two fish species therefore seems to be influenced by intestinal bacteria, as is the case in humans. We could therefore potentially link a blood microbiome to the fish’s diet, which is often difficult to estimate.</p>
<h2>An embryonic, but promising technique</h2>
<p>So this first bacterial mapping of the blood of these two species probably reflects their respective intestinal microbiome. From this characterization, detection of a variation in the composition of bacteria could be linked to stress, a change in the environment or a physiological change in the animal.</p>
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<a href="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="comic strip" src="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=907&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=907&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=907&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Comic strip illustrating the principle of analyzing the circulating microbiome.</span>
<span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>For example, we know that in humans, the loss of <em>Actinobacteria</em> in the circulating microbiome is associated with severe acute <a href="https://doi.org/10.3389/fcimb.2018.00005">pancreatitis</a>. And there are dozens of examples like this in humans.</p>
<p>This study, the result of a collaboration between university researchers from INRS, the University of Québec at Rimouski and the Department of Fisheries and Oceans Canada, provides a small overview of the informative potential offered by the blood microbiomes of fish from the Gulf of St. Lawrence.</p>
<p>Further research will make it possible to estimate their health and better predict the evolution of their population. The dramatic collapse of the cod stock in the late 1980s had a major impact on fishermen. Several of them even fear that this situation will happen again with another species. As turbot remains a species at risk, it is essential to ensure better management of St. Lawrence species.</p>
<p>Only by refining our analysis techniques and deepening our scientific knowledge can we prevent this type of collapse from happening again in the future.</p><img src="https://counter.theconversation.com/content/217025/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fanny Fronton received a grant from the Fondation Armand Frappier.</span></em></p>Blood isn’t sterile, and analyzing the bacteria in it could help assess the health of fish and prevent the collapse of their populations.Fanny Fronton, Doctorante en Écologie halieutique et biologie moléculaire, Institut national de la recherche scientifique (INRS)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2157162023-10-24T13:17:12Z2023-10-24T13:17:12ZTiny and mysterious: research sheds light on sub-Saharan Africa’s seahorses, pipefish and pipehorses<figure><img src="https://images.theconversation.com/files/554212/original/file-20231017-25-sspl51.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A giraffe seahorse (_Hippocampus camelopardalis_).</span> <span class="attribution"><span class="source">Louw Claassens</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Seahorses are considered <a href="https://www.uw360.asia/incredible-stories-of-seahorses/">fabled creatures</a> by many; something that only exists in old mythical tales of the ocean. But these curious animals really exist – and they’re not the only members of the Syngnathidae family of fishes. Other <a href="https://pubmed.ncbi.nlm.nih.gov/27989632/">syngnathids</a> are pipefish, pygmy pipehorses and seadragons, and all are enchanting.</p>
<p>Sadly, syngnathids all over the world are at risk. They face <a href="https://www.cambridge.org/core/services/aop-cambridge-core/content/view/012328F0402196FC932FF5D45809D261/S0030605320000782a.pdf/div-class-title-global-extinction-risk-for-seahorses-pipefishes-and-their-near-relatives-syngnathiformes-div.pdf">major threats</a>, ranging from both intentional and unintentional harvesting to habitat loss and alterations. Syngnathids are commonly found in shallow, coastal environments, which magnifies the impacts of these threats. </p>
<p>Syngnathids, and specifically seahorses, are the subject of various <a href="https://projectseahorse.org/">global</a> and <a href="https://www.biodiversa.eu/2023/04/19/eurosyng/">regional</a> research initiatives. They are relatively well studied in many parts of the world. This is, however, not true for sub-Saharan Africa. Most of the published research from the region has focused on the endangered Knysna seahorse (<em>Hippocampus capensis)</em> and the critically endangered estuarine pipefish (<em>Syngnathus watermeyeri</em>), both found in South Africa. Recently, a pygmy seahorse (<em>Hippocampus nalu</em>) <a href="https://theconversation.com/how-an-underwater-photo-led-to-the-discovery-of-a-tiny-new-seahorse-species-136962">was also discovered</a> in Sodwana Bay, South Africa – the first ever recorded from Africa. </p>
<p>But South Africa is just one country on a vast continent. This prompted us to conduct a comprehensive <a href="https://www.researchgate.net/publication/365460497_Diversity_Distribution_Ecology_and_Conservation_Status_of_the_Family_Syngnathidae_in_Sub-Saharan_Africa_and_Adjacent_Islands">review</a> of the diversity, distribution, ecology and conservation status of the family Syngnathidae in sub-Saharan Africa and adjacent islands. We attempted to collate all existing information, data and observations of syngnathids in the region. </p>
<p>Our findings unveiled a total of 63 syngnathid species across 26 genera in the study area. Mozambique exhibited the highest species diversity, followed by Madagascar and South Africa. There were many interesting, exciting data points, but it also became evident that regionally much needs to be done in terms of research and conservation action on the ground (or rather, in the water!). </p>
<h2>How we did it</h2>
<p>It’s no easy task to gather information for this kind of review, especially because there isn’t a lot of published information available. As a first step, we did a deep dive to collate all peer reviewed published articles, as well as information produced outside traditional publishing and distribution channels, such as management plans and government documents.</p>
<p>We then turned to the African marine community, reaching out to our network of keen divers and researchers within the region. We also used various citizen science platforms such as <a href="https://projectseahorse.org/iseahorse/">iSeahorse</a> and even created an <a href="https://www.inaturalist.org/projects/syngnathids-of-africa">iNaturalist project</a> for all syngnathid observations in sub-Saharan Africa. On iNaturalist, people could log their observations with the location, drawing on the wider community for help with identification where needed. </p>
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Read more:
<a href="https://theconversation.com/how-an-underwater-photo-led-to-the-discovery-of-a-tiny-new-seahorse-species-136962">How an underwater photo led to the discovery of a tiny new seahorse species</a>
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<p>The response from the marine community and observations logged on iNaturalist yielded some wonderful results. For instance, the discovery of a <a href="https://www.inaturalist.org/observations/81180257">new species</a> of pipehorse, currently under peer review.</p>
<h2>What we found</h2>
<p>Once all the data was collected and collated, some key findings emerged. </p>
<p>There is limited information on the biology of sub-Saharan syngnathids, making it tough to understand the population dynamics, habitat use and association, and life history of species. This highlights the need for further species-specific research. </p>
<p>Most assessments that included information on syngnathid populations came from general fish surveys. It is very tough to find syngnathids and they tend to be sparsely distributed, so <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/edn3.365">targeted survey approaches</a> are needed to detect them.</p>
<p>Twenty percent of syngnathid species found in the region are listed as <a href="https://www.iucnredlist.org/search?redListCategory=dd">data deficient on the IUCN Red List</a>. One example is <em>Bulbonaricus brucei</em>, which is only known from its type specimen (the first specimen collected and used to describe the new species). There have been no published observations of this species after its initial description in 1971. This highlights the need for locally significant and current data. </p>
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Read more:
<a href="https://theconversation.com/dna-in-the-water-shows-south-african-scientists-where-to-find-a-rare-pipefish-193229">DNA in the water shows South African scientists where to find a rare pipefish</a>
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<p>Sub-Saharan syngnathids are susceptible to the same threats as species elsewhere in the world, like harvesting, poaching, impacts from by-catch and habitat loss and alteration. We concluded that different species face different types of threats based on where they are found along the seascape. Similarly, what would work in terms of conservation actions depends on the species and where it is found. </p>
<p>To illustrate this, we created <a href="https://www.researchgate.net/publication/365460497_Diversity_Distribution_Ecology_and_Conservation_Status_of_the_Family_Syngnathidae_in_Sub-Saharan_Africa_and_Adjacent_Islands">a schematic</a> summarising the main threats and the most suitable conservation actions across the seascape for all syngnathids found in sub-Saharan Africa.</p>
<h2>More to learn</h2>
<p>It’s clear from this review that sub-Saharan Africa is home to many weird and wonderful syngnathids. We believe that many remain to be discovered. However, it is also apparent that research and conservation actions must be scaled up. Scientists need to conduct more species-specific assessments to develop locally significant management and conservation actions. It’s also crucial to untangle syngnathid diversity and taxonomy in the region for deeper understanding, combined with the development and support of local expertise.</p><img src="https://counter.theconversation.com/content/215716/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louw Claassens receives funding from National Geographic Society and the Rufford Foundation </span></em></p><p class="fine-print"><em><span>David Harasti and Graham Short do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sub-Saharan Africa is home to many weird and wonderful seahorses and pipefish. But they’re under threat.Louw Claassens, Research Associate of Zoology and Entomology, Rhodes UniversityDavid Harasti, Adjunct assistant professor, Southern Cross UniversityGraham Short, Research Associate, Australian MuseumLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2131402023-10-15T12:27:54Z2023-10-15T12:27:54ZHow climate change-induced stress is altering fish hormones — with huge repercussions for reproduction<p>In <a href="https://doi.org/10.1126/science.213.4507.577">1981, scientists discovered that female fish exposed to high temperatures developed testes instead of ovaries</a>. Since then, over 1,100 studies on different animal species, including 400 on freshwater fish, have found similar results.</p>
<p>This raises several questions.</p>
<p>Why does this happen? How can this be explained, and does it harm long-term fish populations? Our research has shown that a key factor in explaining this is the over-production of stress hormones as a result of higher temperatures.</p>
<h2>No time to adapt</h2>
<p>Fish reproductive organs are highly adaptable to environmental changes as, unlike mammals, <a href="https://doi.org/10.1016/S0044-8486(02)00057-1">they have simple structures</a>. Remarkably, even slight changes in water conditions can directly and significantly <a href="https://doi.org/10.1038/s41586-019-1132-4">impact fish metabolism and physiology</a>.</p>
<p>Fish use this to their advantage by using environmental cues to <a href="https://doi.org/10.1007/s00018-020-03532-9">align their reproductive success with seasonal conditions</a>. For example, several fish species, like the <a href="https://www.alberta.ca/lake-sturgeon">yellow sturgeon, breed in the springtime cued by the warmer water temperatures</a>.</p>
<p>However, sudden environmental changes brought about by climate change are drastically affecting fish populations and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880135/pdf/rstb20100055.pdf">pushing some of them to move to more suitable breeding habitats</a>.</p>
<h2>Temperature can change female to male fish</h2>
<p>Studying how female fish become male (or are masculinized) through temperature change has led to a significant breakthrough. When fish are exposed to temperatures outside their normal range, they become stressed and experience a high level of the <a href="https://my.clevelandclinic.org/health/articles/22187-cortisol">stress hormone called cortisol</a>. This is the case for several fish species, such as the <a href="https://doi.org/10.1111/j.1095-8649.2010.02780.x">Argentinian silverside</a>, <a href="https://doi.org/10.1159/000100035">medaka</a> and <a href="https://doi.org/10.1073/pnas.1609411114">zebrafish</a>. </p>
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Read more:
<a href="https://theconversation.com/if-we-protect-mangroves-we-protect-our-fisheries-our-towns-and-ourselves-214390">If we protect mangroves, we protect our fisheries, our towns and ourselves</a>
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<p>Interestingly, the same enzyme that generates cortisol is also in charge of producing the most potent male hormone in fish called <a href="https://doi.org/10.1210/jc.2016-2311">11-ketotestosterone</a>. The role of this male hormone is to trigger the development of male sexual characteristics in fish. </p>
<p>If fish experience stress — i.e., an increase in cortisol — from high temperatures, it can tilt the hormonal balance in fish larva and result in testes development. The overproduction of androgens results in more males developing than females under high temperatures.</p>
<h2>Not just stress</h2>
<p>In <a href="https://doi.org/10.1242/dev.172866">2019</a>, our research group demonstrated that blocking stress receptors through <a href="https://www.nih.gov/news-events/gene-editing-digital-press-kit">gene editing tools</a> completely suppressed fish masculinization induced by high temperatures. These results reveal, for the first time, that the brain acts as a driver of masculinization induced by thermal stress. </p>
<p>In our new study published in <a href="https://doi.org/10.1007/s00018-023-04913-6"><em>Cellular and Molecular Life Sciences</em></a> in 2023, we further demonstrated that thyroid hormones, in addition to stress hormones, are involved in fish masculinization. Once again, through gene editing, we were able to block stress receptors and show that the thyroid hormone pathway is affected when fish experience stress. </p>
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<img alt="Two fish larvae seen close-up." src="https://images.theconversation.com/files/553544/original/file-20231012-25-xn0fir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553544/original/file-20231012-25-xn0fir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553544/original/file-20231012-25-xn0fir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553544/original/file-20231012-25-xn0fir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553544/original/file-20231012-25-xn0fir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553544/original/file-20231012-25-xn0fir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553544/original/file-20231012-25-xn0fir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The larvae of the fish species Centrarchid. Warming temperatures are causing fish larvae to disproportionately develop male sex organs.</span>
<span class="attribution"><span class="source">(Wikimedia Commons)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>It was observed that when cortisol and thyroid hormone production were suppressed through the combined use of chemical drugs, no females were masculinized. Understanding the molecular mechanisms behind fish sex determination helps predict how climate change-induced temperature can affect fish populations in the future.</p>
<h2>Role of pollution</h2>
<p>Several environmental contaminants, like pesticides and plasticizers, are known to <a href="https://doi.org/10.1016/j.envres.2022.112849">upset the balance of hormones in animals</a>. These contaminants — known as endocrine-disrupting chemicals — <a href="https://doi.org/10.1016/j.envres.2021.112584">can lead to sex organs developing abnormally in fish</a>. </p>
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Read more:
<a href="https://theconversation.com/five-options-for-restoring-global-biodiversity-after-the-un-agreement-196835">Five options for restoring global biodiversity after the UN agreement</a>
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<p>With climate change, environmental factors that affect sexual development are now a major issue. Lately, temperatures have been fluctuating drastically, both low and high, exceeding the acceptable range for most fish species. Such changes cause high temperature events, acidification, and hypoxia <a href="https://doi.org/10.1098/rspb.2011.0529">that can distort fish sex ratio</a> by skewing it towards males, and even resulting in all-male fish populations. </p>
<p>In rivers and lakes, the inter-annual events of El Niño or La Niña can also be altered by climate change, which can cause severe periods of flood or drought. This can exacerbate stresses to fish and too few females in a fish population can cause it to collapse, with dire consequences in biodiversity for us all.</p><img src="https://counter.theconversation.com/content/213140/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Valérie S. Langlois has received funding from the Canada Research Chair Program to conduct this work.
</span></em></p><p class="fine-print"><em><span>Diana Castaneda-Cortes received funding from Doctoral fellow of the CONICET, Argentine National Research Council, 2015-2020. </span></em></p><p class="fine-print"><em><span>Juan Ignacio Fernandino has received funding from the Argentinean National Agency for the Promotion of Science and Technology (AGENCIA) to conduct this work.</span></em></p>Climate change is causing higher levels of stress in fish, and the resulting hormonal imbalances are fundamentally altering entire populations.Valérie S. Langlois, Professor/Professeure titulaire, Institut national de la recherche scientifique (INRS)Diana Castañeda-Cortés, Postdoctoral, Institut national de la recherche scientifique (INRS)Juan Ignacio Fernandino, Associate research scientist, Developmental Biology Laboratory, Instituto Tecnológico de Chascomús (CONICET-UNSAM), Universidad Nacional de San MartínLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2111432023-09-26T15:16:39Z2023-09-26T15:16:39ZWhat’s the carbon footprint of owning pet fish? An expert explains<figure><img src="https://images.theconversation.com/files/549367/original/file-20230920-21-sqqv47.jpeg?ixlib=rb-1.1.0&rect=40%2C0%2C4464%2C2967&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">One of the most popular species of fish found in tropical marine aquariums is the common clownfish (Amphiprion ocellaris).</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/unhappy-clown-fish-swims-aquarium-tank-1449838790">jflin98/Shutterstock</a></span></figcaption></figure><p>While the environmental impact of having <a href="https://theconversation.com/how-cats-and-dogs-affect-the-climate-and-what-you-can-do-about-it-206812">dogs and cats</a> as pets has been examined to some extent, the impact of keeping pet fish has remained unexplored – until now. </p>
<p>Dogs in particular have a significant carbon “<a href="https://theconversation.com/what-about-your-carbon-pawprint-9878">pawprint</a>”. An average-size dog (weighing 10-20kg) in Europe is <a href="https://doi.org/10.1093/biosci/biz044">responsible</a> for between 349 and 1,424kg of CO₂-equivalent emissions per year – compared with between 150kg and 251kg of CO₂-eq for an average-size cat (weighing 2kg-6kg). </p>
<p>But there had never been a study examining the carbon footprint of pet fish, despite <a href="https://ornamentalfish.org/wp-content/uploads/OATA-Annual-Report-2020-21-online.pdf">4 million</a> households owning them in the UK alone – <a href="https://www.ornamentalfish.org/wp-content/uploads/2012/08/Customer-Profile-Survey-Results-2011-2012.pdf">70% of which</a> are tropical freshwater fish.</p>
<p>My <a href="https://doi.org/10.1111/jfb.15478">study</a> found the carbon footprint of a tropical aquarium in the UK ranges from 85.3kg to 635.2 kg of CO₂-eq per year – equivalent to between 1.6% and 12.4% of the average UK household’s annual emissions. This estimate is based on a range of scenarios including aquarium sizes between 50 and 400 litres and different tank operating conditions. But most household aquariums sold by retailers are in the 50-to-100 litre range.</p>
<p>Electricity generation is the main source of emissions from tropical aquariums. Maintaining one requires lots of electricity to power the heaters, lights and pumps. This electricity consumption is much greater in emissions terms than the CO₂ produced in transporting tropical fish from countries such as Singapore or Indonesia to the UK and Europe.</p>
<p>However, the precise carbon footprint of an aquarium varies depending on its location. For example, tropical fish kept in France have a much smaller carbon footprint than those kept in the UK, because the French electricity grid is <a href="https://ember-climate.org/countries-and-regions/countries/france/">more decarbonised</a>.</p>
<p>This also means that as electricity grids continue to decarbonise globally, and especially in Europe, the carbon footprint of keeping tropical fish will decrease.</p>
<figure class="align-center ">
<img alt="Two graphs showing the carbon emissions of keeping pet fish" src="https://images.theconversation.com/files/547316/original/file-20230909-48264-8gkxww.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547316/original/file-20230909-48264-8gkxww.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547316/original/file-20230909-48264-8gkxww.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547316/original/file-20230909-48264-8gkxww.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547316/original/file-20230909-48264-8gkxww.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=349&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547316/original/file-20230909-48264-8gkxww.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=349&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547316/original/file-20230909-48264-8gkxww.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=349&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">(a) Yearly carbon emissions produced by heating different-sized aquariums in three countries (green = Poland, blue = UK, red = France) whose electricity grids have various levels of decarbonisation. (b) Yearly carbon emissions of running a 200 -litre aquarium (2000-2022) and predicted emissions for 2040 based on pledges to decarbonise electricity grids.</span>
<span class="attribution"><span class="source">Perry; Journal of Fish Biology (2023)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Water consumption</h2>
<p>Water consumption is another factor to consider. Tropical aquariums are closed systems so fish waste can build up, increasing the levels of ammonia which is deadly to fish. So, fishkeepers must perform regular water changes – which means replacing the aquarium water with treated tap water or, for marine fish, water that has been purified using <a href="https://www.practicalfishkeeping.co.uk/features/what-you-need-to-know-about-reverse-osmosis/">reverse osmosis</a> (whereby water is pushed under pressure through a semi-permeable membrane). However, reverse osmosis is not efficient and produces five litres of reject water for every one litre of purified water.</p>
<p>Estimates of water consumption for tropical aquariums vary depending on aquarium size, use of reverse osmosis, frequency of water changes and amount of water replaced. Based on industry recommendations and a range of aquarium sizes, I estimated that tropical aquariums can use anywhere between 156 and 31,200 litres of water per year.</p>
<p>For example, if you have a 50-litre aquarium and you change 6% of the water <a href="https://www.fishkeeper.co.uk/faq/how-often-and-much-do-i-need-to-change-my-aquarium-water-and-clean-my-filter/">every week</a> with tap water, you would use 156 litres per year. But if you have a 400-litre aquarium and do a 25% water change every week with a reverse osmosis system, you could use up to 31,200 litres per year. </p>
<p>Clearly, these examples represent two extremes of water consumption, equivalent to between 0.2% and 30.1% of the average UK household’s annual water use. While the upper limit can sound alarming, most aquariums sit in the middle range by both water use and emissions. But, given that drought events are expected to increase under future climate scenarios, any additional levels of water consumption can quickly become unsustainable. </p>
<p>Context is also important, as estimates on energy consumption are based on the aquarium being in a 20C (68F) room. If a central heating system is on all day or it is a warm summer’s day, this will reduce the emissions generated from heating the aquarium. Alternatively, if the room is colder than 20C, those emissions will be higher – although the heat from the aquarium will also heat the room, so may be viewed as an electric radiator.</p>
<h2>Ways to reduce environmental impact of pet fish</h2>
<p>My estimates provide the first insights into the environmental impact of a popular hobby. They show that keeping tropical fish is generally a more environmentally friendly option than keeping a dog or even a cat.</p>
<p>They can also inform our decisions on how to reduce the environmental impact of keeping fish, such as: </p>
<ol>
<li><p>Use renewable electricity, generated at home or by changing electricity provider.</p></li>
<li><p>Keep the water temperature as low as possible according to species guidelines. </p></li>
<li><p>Put aquarium lights and pumps on timers. </p></li>
<li><p>Only do water changes when necessary; and </p></li>
<li><p>Re-use the reject water both from your aquarium and the reverse osmosis system. </p></li>
</ol>
<p>Keeping tropical fish is a great way to enjoy beautiful ecosystems in your home. Done correctly, it can also help prevent the world from becoming a little bit more tropical.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<p class="fine-print"><em><span>William Perry does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research reveals the environmental impact of keeping tropical fish as household pets – but there are ways to reduce it.William Perry, Postdoctoral Research Associate at the School of Biosciences, Cardiff UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2072842023-08-28T12:03:27Z2023-08-28T12:03:27ZWhat social change movements can learn from fly fishing: The value of a care-focused message<figure><img src="https://images.theconversation.com/files/544486/original/file-20230824-17-xz9a9n.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2811%2C1863&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fly-fishing in Alaska's Tongass National Forest.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/fB1dRF">Joseph/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Summer and fall are prime times for getting outdoors across the U.S. According to an annual survey produced by the outdoor industry, 55% of Americans age 6 and up participated in <a href="https://outdoorindustry.org/resource/2023-outdoor-participation-trends-report/">some kind of outdoor recreation</a> in 2022, and that number is on the rise. </p>
<p>However, the activities they choose are shifting. Over the past century, participation has declined in some activities, <a href="https://theconversation.com/fewer-americans-are-hunting-and-that-raises-hard-questions-about-funding-conservation-through-gun-sales-176220">such as hunting</a>, and increased in others, <a href="https://www.nationalgeographic.com/travel/article/could-a-boom-in-us-birding-help-fund-conservation">like bird-watching</a>. </p>
<p>These shifts reflect many factors, including demographic trends and urbanization. But outdoor activities also have their own cultures, which can powerfully affect how participants think about nature. </p>
<p>As scholars who think about <a href="https://scholar.google.com/citations?user=u6FOkIQAAAAJ&hl=en">organizational theory</a>, <a href="https://scholar.google.com/citations?user=F1RxMTcAAAAJ&hl=en">management</a> and <a href="https://scholar.google.com/citations?user=hkKa8JcAAAAJ&hl=en">entrepreneurship</a>, we are interested in understanding effective ways to promote social change. In a recent study, we analyzed the work of the nonprofit group <a href="https://www.tu.org/">Trout Unlimited</a>, which centers on protecting rivers and streams across the U.S. that harbor wild and native trout and salmon. </p>
<p>We found that since its founding in 1959, Trout Unlimited has pursued a unique type of social change. Historically, people fished to obtain food – but Trout Unlimited has reframed the sport as <a href="https://doi.org/10.1177/01708406231159490">a vehicle for environmental conservation</a>. It did this by gradually shifting members from catch and keep practices to catch and release, with fish carefully returned to the water. In our view, this strategy offers a powerful example of energizing social change through care, rather than disruptive strategies that emphasize power, anger and fearmongering.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/b_xdC5-G69c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">John McMillan, science director for Trout Unlimited’s Wild Steelhead Initiative, walks through the proper technique to catch and release a type of coastal rainbow trout called steelhead.</span></figcaption>
</figure>
<h2>A sport that inspires devotion</h2>
<p>Fishing is very popular in the U.S.: As of 2016, <a href="https://www.census.gov/content/dam/Census/library/publications/2018/demo/fhw16-nat.pdf">more then 35 million Americans fished</a>, mainly in fresh water. Trout Unlimited was <a href="https://www.tu.org/about/#:%7E:text=Founded%20in%20Michigan%20in%201959,coldwater%20fisheries%20and%20their%20watersheds.">founded in 1959</a> on the banks of Michigan’s Au Sable River with the aim of building a strong conservation ethic among anglers. Today, the group has more than 300,000 members spanning hundreds of local chapters across the U.S. </p>
<p>Many Trout Unlimited members prefer fly fishing, a technique that uses a rod, reel, specialized weighted fishing line and artificial flies designed to mimic trout’s natural food sources. Trout generally thrive in beautiful, fast-flowing, cold-water streams and rivers; to catch them, fly fishers repeatedly cast a line so that their lure moves like a flying insect landing and floating on the water. It’s a sport that combines deep knowledge of a specific location with time-honored techniques.</p>
<p>In the 1653 classic “<a href="https://www.gutenberg.org/ebooks/683">The Compleat Angler</a>,” English writer Izaak Walton called fly fishing “an art worthy the knowledge and practice of a wise man.” Norman Maclean’s 1976 book “<a href="https://press.uchicago.edu/ucp/books/book/chicago/R/bo3643831.html">A River Runs Through It</a>,” which recounts the author’s childhood experiences fishing Montana’s Big Blackfoot River, declares, “In our family, there was no clear line between religion and fly fishing.” Changing the practices of devoted anglers is no small feat. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CwRq_pAt9je/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Fly-fishing and stewardship</h2>
<p>The first stage of change that Trout Unlimited pursued in its interactions with members was what we call mending – fixing aspects of a practice that are seen as problematic or damaging. For Trout Unlimited, that meant subtly removing harvesting practice from images of fly fishing, while simultaneously reinforcing anglers’ deep connections to rivers. </p>
<p>This reframing began in the late 1960s and continues today, as we learned by analyzing cover images and editorials from “Trout,” the organization’s member magazine, and interviewing staffers at Trout Unlimited and others throughout the fly fishing industry. Editors of “Trout” scrubbed away images of harvesting gear, such as <a href="https://www.montanaoutdoor.com/2020/03/creels/">creels</a>, <a href="https://www.youtube.com/watch?v=hrp-r1iavHY">stringers</a> and spears. Instead, they featured photos of trout being safely released and of caught fish remaining underwater in their environment. </p>
<p>These changes did not directly speak to or challenge anglers’ practices. Instead, they worked more subtly. “Trout” editors also began to describe old harvesting artifacts like creels as “something of a curio” and “relics of the past.” </p>
<p>In another editorial shift, the magazine increasingly featured images of vast river landscapes rather than close-up photos of people fishing. This approach elevated the experience of being in nature above that of catching fish. </p>
<p>Editors included poetry and sermonettes in the magazine that modeled normative values of conservation and catch and release practices. Here’s one example: </p>
<blockquote>
<p><em>Carefully I reach out, and lift him in my net,</em></p>
<p><em>But I make sure not to touch him, until my hands are wet.</em></p>
<p><em>For not doing so would damage him, and that would not be right,</em></p>
<p><em>For this indeed I owe him, for such a noble fight.</em></p>
<p><em>As gently as I can, I remove the hook and set him free …</em></p>
</blockquote>
<p>Using words and images, the magazine sought to trigger positive emotions and a sense of deep connection and love for trout. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CSouKfBB_IY/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Caring for fishing grounds</h2>
<p>As Trout Unlimited built momentum in the 1960s and ’70s, the organization made river and stream restoration a major priority. This period marked the birth of the modern environmental movement. Americans were recognizing that industrial development was harming precious natural resources, including fishing grounds. </p>
<p>Logging had <a href="https://www.nwcouncil.org/reports/columbia-river-history/logging/">ravaged wetlands and stream banks</a> along river corridors. Dam construction, particularly in Western states, was <a href="https://theconversation.com/removing-dams-from-the-klamath-river-is-a-step-toward-justice-for-native-americans-in-northern-california-196472">blocking fish passage</a>, preventing trout and salmon from swimming upstream to their spawning grounds. Acid drainage from mining operations was <a href="https://www.tu.org/conservation/conservation-areas/watershed-restoration/abandoned-mine-reclamation/">contaminating waterways</a>. And recreational and commercial fishers were over-harvesting many important species.</p>
<p>Trout Unlimited chapters organized events that ranged from local river cleanups to advocating for federal Wild and Scenic designation for free-flowing rivers and streams. This status <a href="https://www.fs.usda.gov/managing-land/wild-scenic-rivers#">protects them from overuse and in-stream development</a>, such as dams and irrigation diversions.</p>
<p>Members also campaigned for dam removal to open up fish spawning habitat and for creating “<a href="https://riverreporter.com/stories/special-trout-fishing-regulations,43375">no-kill” zones</a> along stretches of rivers, where catch and release was required. Trout Unlimited framed these efforts as supporting fly fishing through positive change. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1669845059661881344"}"></div></p>
<h2>An inclusive message</h2>
<p>Today, Trout Unlimited <a href="https://www.tu.org/conservation/">centers conservation in its mission</a> of protecting, reconnecting, restoring and sustaining coldwater fisheries. We see the organization as an important model in a world driven by social media algorithms that <a href="https://theconversation.com/hate-cancel-culture-blame-algorithms-129402">amplify negative emotions</a>. In our view, driving change through actions that represent love and care, rather than <a href="https://doi.org/10.1080/14693062.2022.2143315">anger and shame</a>, could engage more people in tackling major social challenges.</p>
<p>This approach does have limitations. It is useful when a practice can be altered to be more sustainable, as was the case with catch and release. However, as recent research shows, <a href="https://therevelator.org/recreational-fishing-environmental-impact/">recreational fishing still has major environmental impacts</a>, especially on marine species. And sometimes social change requires ending widespread practices altogether. Nonetheless, the key takeaway for us from Trout Unlimited’s work is that social change doesn’t have to vilify in order to succeed.</p><img src="https://counter.theconversation.com/content/207284/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Founded in 1959, the membership group Trout Unlimited has changed the culture of fly-fishing and mobilized members to support conservation. Could its approach work for other social problems?Brett Crawford, Associate Professor of Management, Grand Valley State University Erica Coslor, Senior Lecturer in Management, The University of MelbourneMadeline Toubiana, Associate Professor of Entrepreneurship and Organization, L’Université d’Ottawa/University of OttawaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2110512023-08-07T15:01:24Z2023-08-07T15:01:24ZHow some fish learned to hide behind others to hunt – new research<figure><img src="https://images.theconversation.com/files/541263/original/file-20230804-20-ocohkj.jpg?ixlib=rb-1.1.0&rect=57%2C57%2C6307%2C4179&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/closeup-western-atlantic-trumpetfish-2310048221">Griffin Gillespie/Shutterstock</a></span></figcaption></figure><p>Human hunters once used stalking horses as common practice – a domesticated animal (or a wooden replica), which people guided towards their quarry while crouching behind it. People believed the stalking horse would not spook wildfowl, allowing them to approach their prey within shooting distance without detection. </p>
<p>My team’s <a href="https://doi.org/10.1016/j.cub.2023.05.075">new study</a> found a Caribbean reef fish that adopts the same strategy, providing the first evidence of a predator using another animal for concealment in the wild.</p>
<p>Trumpetfish (<em>Aulostomus maculatus</em>) are predatory fish abundant throughout Caribbean coral reefs. These fish prey on small reef fish and have several different hunting strategies, including hovering upside-down to wait for passing prey. </p>
<p>Divers regularly report seeing trumpetfish <a href="https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1980.tb01458.x">swimming closely alongside</a> a larger typically less-threatening fish, such as a parrotfish or surgeonfish , in a behaviour known as shadowing (also riding or aligning).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Stoplight parrotfish (Sparisoma viride) underwater in the tropical caribbean sea of Bonaire" src="https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541265/original/file-20230804-29-ubxla5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A parrotfish – one of the fish trumpetfish like to hide behind.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/stoplight-parrotfish-sparisoma-viride-underwater-tropical-1564175002">aquapix/Shutterstock</a></span>
</figcaption>
</figure>
<p>Much like the stalking horse, people assumed this behaviour allowed trumpetfish to approach closer to their prey unseen, but this hypothesis had never been tested –until now.</p>
<h2>Model behaviour</h2>
<p>While scuba diving on coral reefs off the Dutch Caribbean island of Curaçao, my team of researchers set up a pulley system to reel a set of 3D-printed models of trumpetfish and parrotfish along a nylon line through the water. The models were reeled one-by-one past groups of damselfish (<em>Stegastes partitus</em>), which are a favourite meal for trumpetfish. </p>
<p>Damselfish respond to potential predators by inspecting approaching fish then fleeing towards their shelter if they sense danger. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/km9H4A71ieo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>So, we filmed and analysed their responses to each model to see if they would detect a hiding trumpetfish. </p>
<p>When a trumpetfish model moved past alone, damselfish swam to inspect the model, then took off back to the safety of their shelter. When a model of an herbivorous parrotfish (<em>Sparisoma viride</em>) swam past by itself, the damselfish gave the model a once over but were far less likely to flee. </p>
<p>However, when we attached a trumpetfish model to the side of a parrotfish model (to replicate the shadowing behaviour of the real trumpetfish) the damselfish reacted almost the same as when it saw a parrotfish model alone: the damselfish did not detect the hidden trumpetfish.</p>
<h2>Why disguise is important</h2>
<p>While many animals use camouflage, even the most well disguised objects become <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2008.0758">noticeable when they’re moving</a>. Animals can struggle to balance their need to move with their need to remain concealed and evolution has helped them develop some creative solutions. For example, the <a href="https://www.australiangeographic.com.au/blogs/creatura-blog/2018/07/wrap-around-spider/">wrap-around spider</a>, found in Australia, spins a new web every evening. At dawn it destroys the web and uses its concave belly to flatten itself around the curve of a tree branch and hide from birds during daylight hours. </p>
<p>And two octopus species “walk” on two tentacles to <a href="https://www.nbcnews.com/id/wbna7286853">camouflage themselves as plants</a> so they can hide from predators. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man crouches behind wooden screen of a horse while he holds a gun" src="https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541244/original/file-20230804-27-fsmt9k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An 1875 image of a human hunter using a stalking horse.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:RO(1875)_P215_APPROACHING_THE_FOWL_WITH_STALKING-HORSE.jpg">British Library</a></span>
</figcaption>
</figure>
<p>There are additional benefits of shadowing behaviour. For example, small trumpetfish may benefit from being less visible to their predators as well as from their prey. Hiding in this way may also reduce the number of aggressive encounters that trumpetfish have with territorial species.</p>
<h2>Climate change shaping behaviour</h2>
<p>Predators often use the physical landscape of a habitat as cover when they hunt their prey, such as hiding among rocky outcrops or vegetation. So the use of other animals may be an important alternative when habitat cover is unavailable. Indeed, in a previous study we found shadowing behaviour <a href="https://link.springer.com/article/10.1007/s00227-022-04057-4#:%7E:text=Discussion,geographically%20clustered%20within%20certain%20areas.">was more common in less complex habitats</a> such as patchy coral reefs. </p>
<p>Coral reefs across the globe are facing increasingly severe challenges, including climate change, pollution and ocean acidification. They are undergoing an alarming rate of degradation, becoming <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0126004#pone.0126004.ref007">patchier, less complex and less biodiverse</a>. Given this trend, we may see an increase in shadowing in the future. </p>
<p>Our study highlights one of the extraordinary strategies predators use to target their prey. Human hunters may have realised that stalking horses could be used to increase their hunting success but it appears fish may have evolved shadowing long before we did.</p><img src="https://counter.theconversation.com/content/211051/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sam Matchette works for the University of Cambridge, UK. This project was funded by the Fisheries Society of the British Isles (FSBI) and the Association for the Study of Animal Behaviour (ASAB). </span></em></p>Trumpetfish are the first known predator to hide behind another animal when hunting.Sam Matchette, Research Associate in Marine Behaviour , University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2107242023-08-06T20:00:22Z2023-08-06T20:00:22ZHow climate change will affect your pet – and how to help them cope<figure><img src="https://images.theconversation.com/files/540802/original/file-20230802-27-obu6yg.jpg?ixlib=rb-1.1.0&rect=139%2C399%2C2301%2C2041&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Earth has just experienced its <a href="https://www.theguardian.com/science/2023/jul/27/scientists-july-world-hottest-month-record-climate-temperatures">hottest month</a> since records began and Australia is now gearing up for an El Niño-fuelled summer. Extreme heat isn’t just challenging for humans – it brings suffering to our beloved pets, too.</p>
<p><a href="https://www.cabidigitallibrary.org/doi/10.1079/cabireviews.2023.0020">Research</a> I was involved in examined how climate change affects the welfare of animals, including pets. My colleagues and I used a concept for assessing animal welfare known as the “<a href="https://kb.rspca.org.au/knowledge-base/what-are-the-five-domains-and-how-do-they-differ-from-the-five-freedoms/">five-domains model</a>”. It’s a science-based structure for examining an animal’s:</p>
<ul>
<li>nutrition </li>
<li>environment </li>
<li>physical health </li>
<li>behaviour</li>
<li>mental state.</li>
</ul>
<p>The model evaluates the complete physiological and behavioural responses of animals to environmental stressors. While the effects of climate change on animals have been studied before, ours is the first study to apply the model to animal welfare specifically. </p>
<p>We examined the academic literature and found climate change will harm animals across all five welfare domains. This applies to both wild and domesticated animals, including pets. So let’s take a look at how various types of pets will fare in a warming world – and how we can help them.</p>
<figure class="align-center ">
<img alt="cat stands in front of fan" src="https://images.theconversation.com/files/540810/original/file-20230802-25-fbsq5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540810/original/file-20230802-25-fbsq5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540810/original/file-20230802-25-fbsq5u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540810/original/file-20230802-25-fbsq5u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540810/original/file-20230802-25-fbsq5u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540810/original/file-20230802-25-fbsq5u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540810/original/file-20230802-25-fbsq5u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Extreme heat isn’t just challenging for humans – our pets may suffer, too.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Fish</h2>
<p>Fish are “ectotherms” – that is, they use external sources of heat to regulate their body temperature. So pet fish are vulnerable to changes in the water temperature of your home aquarium, which may occur during a heatwave.</p>
<p>Extreme water temperatures can cause physical harm to fish. For example, it can increase a fish’s metabolic rate – meaning it <a href="https://e360.yale.edu/features/feeling-the-heat-warming-oceans-drive-fish-into-cooler-waters">needs more oxygen</a> to breathe . It can also <a href="https://www.nepjol.info/index.php/ON/article/view/4331">cause changes</a> such as slowed growth and reduced feeding.</p>
<p>According to <a href="https://agriculture.vic.gov.au/livestock-and-animals/animal-welfare-victoria/other-pets/caring-for-your-pet-fish">official advice</a>, water in an indoor aquarium should generally be kept at between 20°C and 25°C (unless you are keeping tropical fish).</p>
<p>Depending on your budget and aquarium size, you could opt to use a device to control the water temperature. Either way, it’s important to monitor the water temperature regularly. </p>
<p>Also make sure the aquarium isn’t located near a window where it’s exposed to direct sunlight.</p>
<p>Leaving your aquarium unattended for days or weeks in summer can be dangerous, due to the risk of heatwaves. If you’re going on a summer holiday, consider organising a <a href="https://www.thesprucepets.com/holiday-and-vacation-fish-care-and-feeding-1378525#:%7E:text=If%20you%20are%20going%20on,aquarium%20and%20can%20prove%20lethal">fish sitter</a> to check on the animal regularly.</p>
<figure class="align-center ">
<img alt="aquarium in lounge room" src="https://images.theconversation.com/files/540804/original/file-20230802-17-t69u4d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540804/original/file-20230802-17-t69u4d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540804/original/file-20230802-17-t69u4d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540804/original/file-20230802-17-t69u4d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540804/original/file-20230802-17-t69u4d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540804/original/file-20230802-17-t69u4d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540804/original/file-20230802-17-t69u4d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Consider hiring a ‘fish sitter’ while you’re holidaying.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Birds</h2>
<p>Heat stress can change the <a href="https://www.vetexotic.theclinics.com/article/S1094-9194(16)00003-7/fulltext">physiology</a> of birds. For example, research into a wild population of small Australian robins showed during a heatwave, the birds <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/jav.02355">lost body mass</a> and abandoned their nests, and some died. </p>
<p>Heat stress can also cause <a href="https://www.tandfonline.com/doi/abs/10.1207/s15327604jaws0101_5">abnormal behaviour in pet birds</a> such as <a href="https://www.tandfonline.com/doi/full/10.1080/1828051X.2016.1195711?src=recsys">feather picking</a>, when one bird repeatedly pecks at the feathers of another.</p>
<p>In hot weather, regularly check your bird’s cage to make sure it’s clean and stocked with food and water. If the bird is in an outdoor cage or aviary, ensure it is shaded. And a shallow bird bath will help your feathered friend cool off. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wild-bird-feeding-surged-worldwide-during-lockdowns-thats-good-for-people-but-not-necessarily-for-the-birds-210628">Wild bird feeding surged worldwide during lockdowns. That's good for people, but not necessarily for the birds</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="four green birds perch on branch" src="https://images.theconversation.com/files/540807/original/file-20230802-17-3m546p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540807/original/file-20230802-17-3m546p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=391&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540807/original/file-20230802-17-3m546p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=391&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540807/original/file-20230802-17-3m546p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=391&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540807/original/file-20230802-17-3m546p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540807/original/file-20230802-17-3m546p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540807/original/file-20230802-17-3m546p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ensure aviaries are shaded from the sun.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Dogs</h2>
<p>Dogs and cats can suffer on hot days. That’s especially true if they are:</p>
<ul>
<li><a href="https://www.ejmanager.com/mnstemps/100/100-1626960667.pdf?t=1657722662">older or overweight</a></li>
<li>have thick coats</li>
<li>have short snouts/flat faces (which restricts air flow and makes it harder for them to cool down).</li>
</ul>
<p>Heat stress can cause <a href="https://www.frontiersin.org/articles/10.3389/fvets.2021.742926/full?&utm_source=Email_to_ae_&utm_medium=Email&utm_content=T1_11.5e2_editor&utm_campaign=Email_publication&journalName=Frontiers_in_Veterinary_Science&id=742926">canine hyperthermia</a>, which means the dog’s body temperature becomes dangerously hot. </p>
<p>Watch for <a href="https://www.rvc.ac.uk/small-animal-vet/teaching-and-research/fact-files/heatstroke-in-dogs-and-cats#:%7E:text=Early%20signs%20of%20heatstroke%20in%20pet%20animals&text=Panting%2C%20this%20can%20progress%20to,Red%20gums%20or%20tongue">early warning signs</a> of heat stress such as excessive panting and erratic movements. These symptoms can quickly escalate, leading to heat stroke and possible death.</p>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/34828033/">More than 80%</a> of dog owners report exercising their dogs less vigorously, or for shorter periods, during hot weather. That can help avoid heat-related illness. But don’t reduce your dog’s activity levels too much, as that may lead to other health problems. Just time the walks to avoid the heat of the day. </p>
<p>Refrain from leaving dogs unattended in vehicles, because they can easily overheat. In fact, it’s better to leave your dog inside home on a hot day, as long as they have a cool place to rest and plenty of water – perhaps even with ice cubes in it. And dogs love to cool off in a kiddie pool or under a sprinkler.</p>
<p>If you take your dog out on a hot day, <a href="https://agriculture.vic.gov.au/livestock-and-animals/animal-welfare-victoria/dogs/health/heat-and-pets#:%7E:text=Be%20aware%20of%20the%20signs,not%20icy%20water%20and%20fanned">carry</a> a container of fresh, cool water for them. And don’t forget to slip-slop-slap: apply a sparing amount of pet sunscreen to your dogs’ exposed pink skin such as ear tips and nose.</p>
<figure class="align-center ">
<img alt="dog lies in large bucket" src="https://images.theconversation.com/files/540805/original/file-20230802-25-wqyian.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540805/original/file-20230802-25-wqyian.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540805/original/file-20230802-25-wqyian.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540805/original/file-20230802-25-wqyian.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540805/original/file-20230802-25-wqyian.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540805/original/file-20230802-25-wqyian.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540805/original/file-20230802-25-wqyian.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Watch for early signs of heat stress in your pet.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Cats</h2>
<p>Like other animals, cats can overheat in hot weather. Symptoms include panting heavily, drooling and a rapid pulse. Like with other animals, if you suspect your cat is suffering from heatstroke, call a vet immediately.</p>
<p>Climate change and associated heat and floods is likely to aid the spread of parasites and illness <a href="https://www.forbes.com/sites/jeffmcmahon/2022/12/31/guess-whos-loving-climate-change-mosquitos-and-the-pathogens-they-carry/?sh=50654683174a">including</a> tick-borne diseases, <a href="https://pubs.er.usgs.gov/publication/70213352">flea</a> infestations and <a href="https://pubmed.ncbi.nlm.nih.gov/32145530/">heartworm</a>. This puts both cats and dogs at risk.</p>
<p>In hot weather, the advice for cat owners is similar to that of dog owners: ensure your cat has plenty of shade and water, and put pet sunscreen on their ear tips and noses, especially if the cat is white.</p>
<p>If possible, keep the cat inside during the hottest part of the day. Ensure at least one room is cool and ventilated. And in a heatwave, play with your cat either in the early morning or evening, when the temperature has cooled.</p>
<h2>A helping human hand</h2>
<p>While humans have the capacity to understand and prepare for climate change, pets will need our help to cope. This includes not just the pets listed above, but others too, including reptiles, guinea pigs and rabbits.</p>
<p>As heatwaves and other extreme weather events become more common, the onus is on us to keep our pets safe.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-cats-and-dogs-affect-the-climate-and-what-you-can-do-about-it-206812">How cats and dogs affect the climate -- and what you can do about it</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/210724/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Edward Narayan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research shows climate change will harm animal welfare – including your pet.Edward Narayan, Senior Lecturer in Animal Science, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.