tag:theconversation.com,2011:/fr/topics/oceans-183/articlesOceans – The Conversation2024-03-28T20:30:35Ztag:theconversation.com,2011:article/2223592024-03-28T20:30:35Z2024-03-28T20:30:35ZNew electrochemical technology could de-acidify the oceans – and even remove carbon dioxide in the process<p>In the effort to combat the catastrophic impacts of global warming, we must accelerate carbon emissions reduction efforts and rapidly scale strategies to remove carbon dioxide (CO2) from the atmosphere and the oceans. The technologies for reducing our carbon emissions are mature; those for removing carbon from the environment are not, and need robust support from governments and the private sector. </p>
<p>Only 45 per cent of carbon dioxide emissions remain in the atmosphere; the remainder is absorbed through two cycles: 1) <a href="https://earthobservatory.nasa.gov/features/CarbonCycle">the biological carbon cycle</a> stores CO2 in plant matter and soils, and 2) the aqueous carbon cycle absorbs CO2 from the atmosphere into the oceans. Each of these cycles accounts for 25 per cent and 30 per cent of emitted CO2, respectively.</p>
<p>CO2 that dissolves in the oceans reacts to form chemicals that <a href="https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification">increase the acidity of the oceans</a>. The dissolution of minerals from rocks along coastlines act to counterbalance this acidity, in a process called geological weathering, but the extreme increase in the rate and volume of CO2 emissions, especially over the last 60 years, has far exceeded the rate of geological weathering, leading to a 30 per cent increase in ocean acidity. </p>
<p>As the oceans acidify, millions of marine species and whole ecosystems — especially coral reefs — will be unable to adapt. </p>
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Read more:
<a href="https://theconversation.com/cop26-failed-to-address-ocean-acidification-but-the-law-of-the-seas-means-states-must-protect-the-worlds-oceans-171949">COP26 failed to address ocean acidification, but the law of the seas means states must protect the world's oceans</a>
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<p>We are overwhelming the Earth’s natural re-balancing systems and harming its ecosystems in the process. Our recent work at McMaster University and the University of Toronto, supported by the Carbon to Sea Initiative, has attempted to address these challenges.</p>
<h2>The challenge ahead</h2>
<p>The good news is it is possible to re-balance the pH of the oceans using a process called ocean alkalinity enhancement (OAE). What’s more, this rebalancing will also encourage additional CO2 to be absorbed from the atmosphere. By carefully and continually restoring the ocean’s alkalinity, ocean acidification and excess atmospheric CO2 concentrations can be tackled simultaneously.</p>
<p>The most obvious approach would be to <a href="https://doi.org/10.3389/fclim.2024.1338556">add finely ground alkali minerals into the ocean</a> to directly lower the acidity of the water. However, the massive scale at which these processes would have to be enacted is staggering.</p>
<p>For example, we estimate that the equivalent mass of roughly eight thousand Empire State buildings worth of alkaline substance would need to be added into the oceans each year starting by mid-century to meet IPCC emissions targets. Clearly, this technique cannot be the sole solution.</p>
<p>We believe an electrochemical approach operated on decarbonized energy is one of the best ways to combat ocean acidification. <a href="http://dx.doi.org/10.1039/C2EE03393C">Using a process called bipolar membrane electrodialysis (BMED)</a>, the acidity of seawater is removed directly without the addition of other substances. This technology only requires seawater, electricity and specialized membranes. </p>
<p>The simplicity and modularity inherent to the BMED technology allows a flexible, scalable and potentially cost-effective method of carbon dioxide removal. </p>
<h2>Building at scale</h2>
<p>In 2015 — with a team of researchers at the Palo Alto Research Center and X Development — we <a href="https://doi.org/10.1016/j.ijggc.2017.10.007">built and tested</a> a small-scale BMED system. This system <a href="https://doi.org/10.1016/j.ijggc.2018.02.020">performed well</a> and shows great promise when coupled with existing facilities such as desalination plants. </p>
<p>We identified its primary technological limitations, but in 2015-2017, carbon credits and incentives for climate change technologies were insufficient and the project was shelved. Now the economic and physical climate has changed. </p>
<p>On the economic front, both the tax credits provided by the Inflation Reduction Act (IRA) in the United States as well as the steadily <a href="https://www.canada.ca/en/environment-climate-change/services/climate-change/pricing-pollution-how-it-will-work/federal-carbon-pollution-pricing-benchmark.html">rising revenue-neutral carbon tax in Canada</a> are strengthening the economic viability of carbon dioxide reduction technologies. Further, the recent extreme climatic events in the past year from massive wildfires in Canada, to the hottest months on record, to the warmest sea temperatures ever measured, are shocking people into the glaring realities of climate change and increasing the demand for real solutions. BMED technology is one of these solutions. </p>
<p>BMED technology is limited in part by the specialized membranes that are commercially available. What’s more, these membranes account for a significant portion (around 30 per cent) of the capital cost and have short lifetimes as they are <a href="https://doi.org/10.1039/D3EE01606D">susceptible to degradation</a>. </p>
<p>Our work aims to develop scalable, ultra-thin membranes for use in a modified BMED process, while also identifying efficient operational conditions, optimal industrial couplings, and ideal global locations to cost-effectively implement this OAE technology around the world. </p>
<p>The ultra-thin membranes will extract acidity more efficiently than existing commercial membranes, while their manufacturing technique and optimal usage will dramatically decrease their production and operational costs. </p>
<p><a href="https://doi.org/10.1038/s44286-023-00009-x">Developing cost-effective BMED</a> systems will open a pathway to economically viable OAE. </p>
<h2>Cautious optimism</h2>
<p>Recently, several start-ups have been formed — such as <a href="https://www.ebbcarbon.com/">Ebb Carbon</a>, <a href="https://www.seao2.nl/">SeaO2</a> and <a href="https://www.vesta.earth/">Vesta</a> — that target ocean carbon dioxide removal through OAE. </p>
<p>We encourage open communication about the progress and challenges facing OAE with the public, research institutions, governments and the private sector to accelerate solutions to OAE’s challenges. </p>
<p>In particular, we must assess the impact of re-adjusting seawater alkalinity on marine ecosystems while, at the same time, also developing and implementing trusted systems to measure, report and verify the net amount of acidity and carbon removed. </p>
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Read more:
<a href="https://theconversation.com/anthropocene-or-not-it-is-our-current-epoch-that-we-should-be-fighting-for-225428">Anthropocene or not, it is our current epoch that we should be fighting for</a>
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<p>Alongside this, we must also identify optimal large-scale deployment locations where OAE can be safely and effectively implemented. </p>
<p>These considerations are being researched by various groups funded by the Carbon to Sea Initiative, but much more support is needed to rapidly vet and scale this technology. </p>
<p>To overcome the technological challenges and environmental uncertainties, government, industrial, non-profit and venture capital support must be massively scaled and devoted to carefully and responsibly validating the large-scale implementation of OAE technologies around the world.</p><img src="https://counter.theconversation.com/content/222359/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles-Francois de Lannoy receives funding from Carbon to Sea, NSERC, OCI, Ontario Ministry of Colleges and Universities ERA, MITACS, Trojan Technologies, Aria Filtra, ESI Informatics, the ELAP Fellowship, Imperial, and McMaster University. </span></em></p><p class="fine-print"><em><span>Bassel A. Abdelkader receives funding from Carbon to Sea. </span></em></p><p class="fine-print"><em><span>Jocelyn Riet receives funding from Carbon to Sea. </span></em></p>Global warming is making the oceans more acidic. Our work aims to design realistic systems to reduce this acidity, and remove carbon from the atmosphere in the process.Charles-Francois de Lannoy, Associate Professor, Chemical Engineering, McMaster UniversityBassel A. Abdelkader, Postdoctoral Researcher, Department of Chemical Engineering, McMaster UniversityJocelyn Riet, Ph.D. Candidate in Chemical Engineering, University of TorontoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2247152024-03-27T13:27:11Z2024-03-27T13:27:11ZGo on an Easter egg case hunt on the beach to discover more about sharks and rays<figure><img src="https://images.theconversation.com/files/579193/original/file-20240301-20-bnz9ap.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Egg cases found along the foreshore can tell scientists a lot about the abundance and life cycles of sharks and rays</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-shark-egg-case-resting-on-1983639383">Ross Mahon/Shutterstock</a></span></figcaption></figure><p>Strolling along the shoreline, you may come across peculiar pouch-like objects on the sand. These leathery treasures are shark egg cases, also known as mermaid’s purses. Each capsule can tell us something about how sharks and rays reproduce, the lives they lead and how rare they might be. </p>
<p>The Shark Trust’s <a href="https://www.sharktrust.org/greateggcasehunt">great egg case hunt</a> encourages people to document their foreshore findings. Different sharks and rays produce egg cases with distinct characteristics. Skates and rays tend to have more elongated pouches with horn-like protrusions at each end. Shark egg cases often have spiral coiled tendrils which can be lodged into crevices or attached to underwater structures such as rocks, seaweed, or coral reefs.</p>
<p>These protective structures are produced by the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0016648022001010#:%7E:text=Reproductive%20strategies%20of%20elasmobranchs%20(sharks%2C%20rays%20and%20skates)%20have,species%20(Compagno%2C%201990).">40% of sharks and rays</a> and <a href="https://www.sharktrust.org/pups-skates-rays">all skates</a> that lay eggs. Each egg case safeguards an embryo from predators and harsh environmental conditions during their early stages of life. </p>
<p>Shark egg cases can be found around the world, in coastal waters, estuaries and deep ocean environments. Particularly after storms or during low tide, egg cases may become dislodged from their attachment sites on the ocean floor and end up on beaches. </p>
<h2>Record your findings</h2>
<p>If you come across an egg case while exploring the beach, try not to disturb or open it because it may contain precious shark or ray eggs. Avoid removing it from the beach (doing so may well be illegal in some parts of the world) and, as with any beach discovery, leave the area as you found it.</p>
<p>Take a moment to examine the egg case. Note its size, shape, colour and any other distinguishing features. Photograph the egg case from different angles and try to identify which species it came from using The Shark Trust’s <a href="https://www.sharktrust.org/geh-id">useful guide</a>. Record the precise location, date and time that you found the egg case. </p>
<p>Log your findings via citizen science projects such as the great egg case hunt, or report your discovery to local marine research organisations, aquariums or conservation groups that may be collecting data on egg case sightings. </p>
<p>Share your experience with friends, relatives and other beachgoers to raise awareness about the importance of shark and ray conservation. Encourage others to respect marine life and their habitats to ensure their preservation.</p>
<h2>A natural process</h2>
<p>The washing up of shark egg cases is a perfectly natural process. Some sharks and rays deposit their egg cases in shallow waters or near the shoreline, where they may become dislodged by wave action, currents, or storms. This helps to disperse the embryos and maintain genetic diversity within populations. Once the tide comes in, egg cases can be washed back into the sea allowing for further dispersal, so not all shark egg cases found on beaches are stranded or in need of intervention. </p>
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<a href="https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Underwater shot of yellow transparent egg case with dark-coloured live embryo inside , purple sea coral" src="https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579203/original/file-20240301-18-pcqiev.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">Egg cases are designed to protect the embryos of sharks and rays.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dogfish-shark-eggs-close-hanging-red-326395700">Andrea Izzotti/Shutterstock</a></span>
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<p>If the embryos inside the egg cases are fully developed and ready to hatch, returning them to the sea may indeed increase their chances of survival. But if the water is too shallow, turbid or polluted, it may not be suitable for the survival of the embryos. Handling egg cases or disturbing them unnecessarily could inadvertently harm the developing embryos. So if you have concerns about the welfare of the embryos or the environmental conditions, consult with local marine conservation experts or beach authorities for guidance.</p>
<h2>Tracking cycles</h2>
<p>Identifying which species are present in a particular area can indicate the reproductive activity of local shark and ray populations. By monitoring the abundance and distribution of egg cases over time, scientists can track reproductive cycles and assess the health of populations. </p>
<p>While some species may reproduce all year round, others may have specific breeding seasons tied to environmental cues such as water temperature or daylight hours. Understanding the reproductive biology and habitat requirements of sharks and rays helps protect these vulnerable species and conserve their habitats.</p>
<p>Recordings of egg case sightings enable scientists to build up a picture of any changes in the abundance or condition of shark egg cases that might be indicative of broader environmental changes. The decline in the number of egg case sightings may suggest threats such as habitat degradation or over-fishing. Stormy weather or changes in ocean currents may also affect the distribution and abundance of egg cases by washing them ashore or dispersing them in the water. </p>
<p>Egg cases are fascinating structures that provide valuable information about sharks and rays. Next time you visit a beach, remember that each and every piece of debris, natural or human-made, tells a story about the interconnected web of life in the ocean. Take a closer look at what has been washed up on the shore and enjoy going on a shark egg case hunt.</p><img src="https://counter.theconversation.com/content/224715/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas Ray 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>Egg cases of sharks and rays can be found washed up on the shore. Citizen science data helps scientists understand the life cycles of these marine animals and how to best conserve them.Nicholas Ray, Doctoral School Programmes Manager, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2242812024-03-25T13:05:19Z2024-03-25T13:05:19ZAttaching seaweed spores to used scallop shells could restore UK’s coastal kelp forests<figure><img src="https://images.theconversation.com/files/583221/original/file-20240320-16-8972yw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Marine biologists are collecting spores from healthy kelp forests to help restore coastal habitats. </span> <span class="attribution"><span class="source">Marine Biological Association 2024</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Kelp spores are being seeded and grown on small rocks and scallop shells – a seafood waste product – in efforts to regenerate the UK’s coastal kelp forests. </p>
<p>Unlike many other restoration techniques, this method is cheap and easy to carry out. There’s no need for expensive, labour-intensive dive teams to install kelp onto the seabed. </p>
<p>Once gravel or shells have been seeded with kelp in aquariums, teams can simply drop them over the side of a boat where they sink, allowing the kelp to attach to the seabed where it grows to maturity. This is <a href="https://www.nature.com/articles/s41598-020-60553-x">as effective</a> as hand-deployment by divers and far more economical. </p>
<p>Our team of marine scientists is working with the Fishmongers’ Company’s Charitable Trust and the Kelp Conservation Initiative to develop this “green gravel” approach. First pioneered in <a href="https://www.nature.com/articles/s41598-020-60553-x">Norway</a>, green gravel techniques have previously been tested on wave-exposed shores along the north-east <a href="https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/an-assessment-of-the-utility-of-green-gravel-as-a-kelp-restoration-tool-in-waveexposed-intertidal-habitats/3F3671DD02E494988C31E1CF8360F11E">coast of the UK</a>. </p>
<p>Now, in the lab, we are trialling waste scallop shells from the seafood industry and different types of stone from around the UK, easily sourced from hardware stores, as the basis for growing four types of native kelp. Every year, more than <a href="https://www.uclan.ac.uk/articles/research/blackpool-seashell-concrete#:%7E:text=Nationally%20around%2030%2C000%20tonnes%20of,around%2065%20blue%20whales.%E2%80%9D">30,000 tonnes</a> of shells go to landfill in the UK, at a cost to the industry. There’s huge potential to use shells as a restoration material at scale, either whole or crushed into smaller pieces.</p>
<h2>From tanks to seabed trials</h2>
<p>We begin <a href="https://www.nature.com/articles/s41598-020-60553-x">green gravel</a> restoration by identifying a healthy wild population of kelp with adult plants that can be used as donors. Sections of frond filled with spores are cut out and bought back to the lab, then disinfected with a quick dip in iodine solution. </p>
<p>Gravel or scallop shells are cleaned and put into tanks of seawater. The fertile kelp material is dried out overnight then rehydrated to initiate the release of hundreds of millions of microscopic kelp spores. Once extracted, spores are added to tanks of seawater where they settle to seed the gravel or shells.</p>
<p>Spores develop quickly, so tiny kelp seedlings are visible as a brown fuzz within three to four weeks. We monitor growth for three months, then once the kelp plants reach 1cm long, the gravel or shells are taken by boat to test sites off the coasts of Newcastle, Cornwall and Devon. Once dropped over the side of the boat, the stones or shells quickly sink. Over time, the seaweed’s root-like “holdfast” grows to attach securely to the seabed beneath.</p>
<p>By monitoring the growth of these kelp habitats, ideally every few months for several years, we can measure the success of this restoration method. Our early results suggest that a wide variety of UK stone types will be suitable, although success is likely to vary due to local conditions at each site.</p>
<h2>Why restore kelp forests?</h2>
<p>Found along <a href="https://www.sciencedirect.com/science/article/abs/pii/B9780128050521000036">almost a third</a> of the world’s coastlines, kelp are marine algae that can form diverse ecosystems, like forests on land. People depend on the <a href="https://www.nature.com/articles/s41467-023-37385-0">valuable goods and services</a> they provide – from shelter for commercially valuable fish to carbon storage and coastal protection. </p>
<p>But these forests are threatened by warming oceans and marine heatwaves, pollution, poor water quality and overfishing. In many areas, kelp forests are <a href="https://www.pnas.org/doi/full/10.1073/pnas.1606102113">shrinking or have been lost</a> leading to <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/aqc.3880">calls for restoration action</a>. </p>
<p>Seven kelp species, together with other brown seaweeds, cover an area of up to <a href="https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/distribution-and-environmental-requirements-of-large-brown-seaweeds-in-the-british-isles/31A839DE1DE55AFFDD5C0595882A8CEA">20,000 km²</a> along the UK’s rugged coastline. Local declines have been reported in certain areas, including <a href="https://www.frontiersin.org/articles/10.3389/fevo.2022.642775/full">west Sussex</a> and county Durham. </p>
<p>UK kelp forests are not exempt from the impacts of climate change and human activities. Early warning signs include species range shifts, with cold-adapted kelp species <a href="https://www.cambridge.org/core/services/aop-cambridge-core/content/view/5B2FD351846D2144E5D11D02EB7B58BB/S0025315405012506a.pdf/div-class-title-using-historical-data-to-detect-temporal-changes-in-the-abundances-of-intertidal-species-on-irish-shores-div.pdf">declining in southern England</a>, while <a href="https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2745.13053">warm-adapted species are expanding</a> and taking take their place. These changes have knock-on effects in terms of how these ecosystems work, for example in the amount and quality of habitat that they provide for <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2745.13053">other species</a>. </p>
<p>Restoration has been hailed as a tool to regenerate kelp forests in areas where they are shrinking or have been lost, with an <a href="https://kelpforestalliance.com/TNC-KFA-Kelp-Guidebook-2022.pdf">array of techniques</a> being developed around the world.</p>
<p>Almost 200 nations have pledged to protect <a href="https://www.unep.org/resources/kunming-montreal-global-biodiversity-framework">30% of the world’s oceans</a> by 2030, while the <a href="https://link.springer.com/article/10.1007/s10811-023-03103-y">kelp forest challenge</a> – a global initiative run by the Kelp Forest Alliance – aims to protect 4 million hectares of kelp forest by 2040.</p>
<p>But the <a href="https://plymsea.ac.uk/id/eprint/10160/">UK lags behind</a> on the international marine restoration stage, having only recently made limited progress towards restoring seagrass meadows, saltmarshes, oyster reefs and kelp beds.</p>
<p>Our progress over the next three years will inform kelp restoration methods through the <a href="https://www.greengravel.org/action-group">Green Gravel Action Group</a> which recently identified <a href="https://www.frontiersin.org/articles/10.3389/fmars.2024.1364263/abstract">international challenges and solutions</a> to marine forest restoration. Our team is working out how best to adapt green gravel methods to specific locations and wave conditions in the UK. </p>
<p>If scalable and effective in different scenarios, this technique could provide a sustainable use for waste shells, reducing the volume sent to landfill each year nationally, while restoring crucial ocean habitats.</p>
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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>Kelp seaweed spores are being grown on small rocks and waste scallop shells as part of a trial exploring how to regenerate the UK’s coastal kelp forests.Catherine Wilding, Senior Research Assistant, Marine Ecology, Marine Biological AssociationHannah Earp, Postdoctoral Research Associate, Marine Ecology, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2250722024-03-19T14:07:41Z2024-03-19T14:07:41ZGreen lights on fishing nets could slash bycatch of sea turtles, says research<p><a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/j.1755-263X.2010.00105.x">Bycatch in fishing gear</a> is one of the <a href="https://www.worldwildlife.org/initiatives/protecting-turtles-from-the-threat-of-bycatch#:%7E:text=The%20single%20greatest%20threat%20to,and%20leatherbacks%20are%20especially%20vulnerable.">biggest threats</a> to sea turtles. But these creatures are particularly sensitive to <a href="https://www.cell.com/current-biology/pdfExtended/S0960-9822(21)01737-1">green light</a> so they’re less likely to get caught up in fishing nets fitted with green LED lights. </p>
<p>Since 2014, a team of marine biologists and I have been trialling ways to reduce turtle bycatch using lights in nets as a deterrent. Our <a href="https://www.sciencedirect.com/science/article/abs/pii/S0165783623003120#:%7E:text=Recently%2C%20net%20illumination%20has%20also,vulnerable%20species%20in%20set%20nets">recent study</a> shows that these lights can reduce bycatch by approximately 40%.</p>
<p>The adult <a href="https://www.worldwildlife.org/species/green-turtle">green turtles</a> I work with in Cyprus are over a metre long and weigh more than 100kg. The females nest and lay their eggs on Alagadi beach, <a href="https://www.wwf.org.uk/learn/fascinating-facts/marine-turtles#:%7E:text=It%27s%20survival%20of%20the%20fittest,from%20predators%20to%20marine%20plastics.">but only one in a thousand</a> of their tiny hatchlings will survive to adulthood decades later. </p>
<p>Once they have left their nesting beach, young green turtles often wash up dead. <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ddi.12440">Thousands of turtles</a> are <a href="https://www.togetherforthemed.org/our-actions/cyprus-bycatch-7.html">killed annually</a> due to the activities of the Turkish Cypriot fleet alone. </p>
<p>With fish stocks in decline, fishers are using more nets to catch more fish – making bycatch more likely. That effectively negates any conservation efforts to help protect the young green turtles that feed on the coastal seagrass beds. </p>
<p>In this part of the Mediterranean Sea, fishers leave kilometres of net on the seabed overnight in these seagrass habitats. When they haul them in the morning they often find drowned turtles entangled. </p>
<p>But quantifying bycatch is not easy, especially in Cyprus, where hundreds of small fishing boats use different types of fishing gear. It’s even harder to identify the most dangerous fishing methods and prioritise possible solutions. </p>
<p>Together with local fishers and marine authorities, we have monitored impacts on marine life by deploying onboard observers and having fishers report their catches of dolphins, sea turtles, sharks, rays and monk seals.</p>
<p>The <a href="https://www.lindgren-pitman.com/products/lp-electralume-light-w-lithium-battery-add-videos">first lights</a> we trialled were effective, and Cypriot fishers corroborated the positive results from <a href="https://www.int-res.com/abstracts/meps/v408/p241-250/">trials in Mexico</a>. But they found these prototypes difficult to use, with moving metal parts that got tangled in the “set nets”. </p>
<p>These long panels of net which fishers deploy on the seabed are stored in buckets. Due to tangling, the lights needed to be attached and removed on every fishing trip.</p>
<p>They’d often stop working and were not specifically designed for these set nets. At US$40 (£30) per light, the cost of fitting 3km of net is US$12,000. That’s way more than the annual cost of replacing nets that have been cut to release turtles that have got caught.</p>
<p>To make this concept more feasible, we teamed up with Devon-based marine engineering company <a href="https://www.fishtekmarine.com/reduce-turtle-bycatch/">FishTek</a> in 2018 to develop a scalable solution. After years of trials, we developed a more efficient solution known as <a href="https://www.fishtekmarine.com/reduce-turtle-bycatch/">NetLights</a>, which costs just US$8 per light. </p>
<h2>Net illumination</h2>
<p>These battery-powered lights that can be easily attached to huge fishing nets reduce bycatch of turtles <a href="https://www.sciencedirect.com/science/article/abs/pii/S0165783623003120#:%7E:text=Recently%2C%20net%20illumination%20has%20also,vulnerable%20species%20in%20set%20nets">by around 40%</a>. But more trials are needed. </p>
<p>Because the green turtles living around the Cyprus coast keep dying, there aren’t that many of them, so catch rates remain low. Over time, more trials will provide more accurate results. </p>
<p>Thousands of NetLights have been made available to 50 fishers in Cyprus as part of a broader trial. Most are pleased with the target catch rates and ask for more. They’d be most likely to use them if costs are subsidised or if bycatch reduction tech like this is made a legal requirement to safeguard turtles from particular types of fishing net. </p>
<p>Every fisher uses a slightly different net set up and it’s hard to please them all. Ideally, the lights need to be slightly smaller, lighter and more buoyant so that they can replace the floats that fishers use to stand the nets in the water, without adding more bulk. </p>
<h2>Other solutions</h2>
<p>Aside from training fishers to rescue turtles that get entangled, other existing bycatch reduction methods include <a href="https://www.youtube.com/watch?v=sTuB88KaIpQ">turtle excluder devices</a> that fit inside the neck of trawl nets. While small fish and shrimp can pass between the bars to the back of the net, larger turtles bump against the metal grid and can escape through a flap in the mesh net.</p>
<p>In the US, bottom trawlers catching shrimp have to use <a href="https://en.wikipedia.org/wiki/Turtle_excluder_device#cite_note-4">turtle excluder devices</a> to provide an escape route for turtles and other large objects. </p>
<p>Circular fishing hooks which replace “J” shaped hooks are less likely to snag turtles. These have been <a href="https://www.seaturtlestatus.org/articles/2019/1/31/the-continuing-tale-of-circle-hooks-in-brazil">rolled out in large-scale commercial tuna and swordfish fleets</a> on the high seas. But their success has been variable and in some cases reduced target catch can make them economically unsustainable. </p>
<p>If not enforced by governments, measures like these may be requested from supermarkets as part of a bycatch audit to <a href="https://oceandisclosureproject.org/">promote best practice</a> within the supply chain.</p>
<p>In 2023, fisheries policy in northern Cyprus was updated to include some no-take zones and restricted areas to protect fish stocks and other vulnerable species. If properly enforced, both the sea turtles and the fish that fishers rely on will benefit from these measures. </p>
<p>By rolling out more NetLights in set net fisheries that are a top priority for bycatch management, and monitoring their effectiveness against the baseline data we now have, there is huge scope to improve the chance of survival for green turtles.</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>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 30,000+ readers who’ve subscribed so far.</a></em></p>
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<p class="fine-print"><em><span>Robin Snape works at Bluedot Associates UK and has received funding from MAVA Foundation, Lloyd's Register, People's Trust for Endangered Species, Shark Trust, British Chelonia Group and others.</span></em></p>Hi-tech green LED lights attached to fishing gear can act as a deterrent to turtles and help reduce bycatch by approximately 40%.Robin Snape, Associate Researcher, Centre for Ecology and Conservation, University of ExeterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2250882024-03-12T19:15:29Z2024-03-12T19:15:29ZPacific Islanders have long drawn wisdom from the Earth, the sky and the waves. Research shows the science is behind them<p>One afternoon last year, we sat in a village hall in Fiji chatting to residents about traditional ways of forecasting tropical cyclones. One man mentioned a black-winged storm bird known as “manumanunicagi” that glides above the land only when a cyclone is forming out to sea. As the conversation continued, residents named at least 11 bird species, the odd behaviour of which signalled imminent changes in the weather. </p>
<p>As we were leaving later that evening, an elder took us aside. He was pleased we had taken their beliefs seriously and said many older Pacific people won’t talk about traditional knowledge for fear of ridicule.</p>
<p>This reflects the dominance of science-based understandings in adapting to climate change and its threats to ways of life. Our <a href="https://wires.onlinelibrary.wiley.com/doi/10.1002/wcc.882">new research</a> suggests this attitude should change. </p>
<p>We reviewed evidence on traditional knowledge in the Pacific for coping with climate change, and found much of it was scientifically plausible. This indicates such knowledge should play a significant role in sustaining Pacific Island communities in future.</p>
<h2>A proven, robust system</h2>
<p>Our research was co-authored with 26 others, most Pacific Islanders with long-standing research interests in traditional knowledge.</p>
<p>People have inhabited the Pacific Islands for 3,000 years or <a href="https://www.routledge.com/Archaeology-of-Pacific-Oceania-Inhabiting-a-Sea-of-Islands/Carson/p/book/9781032486376">more</a> and have experienced many climate-driven challenges to their livelihoods and survival. They have coped not by luck but by design – through robust systems of traditional knowledge built by diverse groups of people over time.</p>
<p>The main short-term climate-related threats to island livelihoods in the Pacific are tropical cyclones which can damage food crops, pollute fresh water and destroy infrastructure. Prolonged droughts – common during El Niño events in the southwest Pacific – <a href="https://doi.org/10.1007/s10584-021-03112-1">also cause</a> widespread damage.</p>
<p>Traditional knowledge in the Pacific explains the causes and manifestations of natural phenomena, and identifies the best ways to respond. It is commonly communicated orally between generations. </p>
<p>Here, we describe such knowledge relating to animals, plants, water and sky – and show how these beliefs make scientific sense.</p>
<p>It’s important to note, however, that traditional knowledge has its own intrinsic value. Scientific explanations are not required to validate it.</p>
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<strong>
Read more:
<a href="https://theconversation.com/secrets-in-the-canopy-scientists-discover-8-striking-new-bee-species-in-the-pacific-222599">Secrets in the canopy: scientists discover 8 striking new bee species in the Pacific</a>
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</em>
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<h2>Reading the ocean and sky</h2>
<p>Residents of Fiji’s Druadrua Island interpret breaking waves to predict a cyclone as long as one month before it hits. In Vanuatu’s Torres Islands, 13 phrases exist to describe the state of the tide, including anomalies that <a href="https://doi.org/10.1002/j.1834-4461.2004.tb02856.x">herald uncommon events</a>.</p>
<p>These observations make scientific sense. Distant storms can drive ocean swells onto coasts long before the winds and rain arrive, changing the usual patterns of waves.</p>
<p>In Samoa, <a href="https://journals.sagepub.com/doi/abs/10.1177/25148486211047739">ten types of wind</a> are recognised in traditional lore. Winds that blow from the east (matā ‘upolu) indicate the imminent arrival of heavy rain, possibly a tropical cyclone. The south wind (tuā'oloa) is most feared. It will cease to blow, it is said, only when its appetite for death is <a href="https://link.springer.com/article/10.1007/s10584-009-9722-z">sated</a>.</p>
<p>Many Pacific Island communities believe a cloudless, dark blue sky signals the arrival of a tropical cyclone. Other signs include unusually rapid cloud movements and the appearance of “short rainbows”. </p>
<p>These beliefs are supported by science. Rainbows are sometimes “shortened” or partly obscured by a distant rain shower. And Western science has <a href="https://link.springer.com/book/10.1007/978-0-387-71543-8">long recognised</a> changes in clouds and winds can signal the development of cyclones.</p>
<p>In Vanuatu, a halo around a moon signals <a href="https://doi.org/10.1175/wcas-d-13-00053.1">imminent rainfall</a>. Again, this belief is scientifically sound. According to Western science, high thin cirrus clouds signal nearby storms. The clouds contain ice crystals through which moonlight is filtered, creating a halo effect.</p>
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<strong>
Read more:
<a href="https://theconversation.com/teaching-our-children-from-books-not-the-sea-how-climate-change-is-eroding-human-rights-in-vanuatu-192016">'Teaching our children from books, not the sea': how climate change is eroding human rights in Vanuatu</a>
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</em>
</p>
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<h2>The wisdom of animals and plants</h2>
<p>As mentioned above, birds are are said to herald weather changes across the Pacific.</p>
<p>In Tonga, when the frigate bird flies across the land – unusual behaviour for an ocean species – it signals a tropical cyclone is developing. This traditional knowledge is captured in the logo of the <a href="https://met.gov.to">Tonga Meteorological Service</a>. Birds are similarly interpreted in <a href="https://doi.org/10.1080/17477891.2015.1046156">Fiji</a> and <a href="https://doi.org/10.1177/25148486211047739">northern Vanuatu</a>.</p>
<p>This belief stacks up scientifically. One <a href="https://doi.org/10.1016/j.cub.2014.10.079">study</a> in North America, for example, showed golden-winged warblers dodged tornadoes by detecting shifts in infrasound. Another <a href="https://doi.org/10.1038/s41598-019-41481-x">study</a>, which included data on frigate birds in the Pacific, found seabirds appeared to circumvent cyclones, probably by sensing wind strength and direction.</p>
<figure class="align-right ">
<img alt="plantain tree in field" src="https://images.theconversation.com/files/581159/original/file-20240312-18-84kk3r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/581159/original/file-20240312-18-84kk3r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=799&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581159/original/file-20240312-18-84kk3r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=799&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581159/original/file-20240312-18-84kk3r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=799&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581159/original/file-20240312-18-84kk3r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581159/original/file-20240312-18-84kk3r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581159/original/file-20240312-18-84kk3r.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">
<figcaption>
<span class="caption">When the central shoot of the plantain is curled, people know a cyclone is developing.</span>
<span class="attribution"><span class="source">Patrick Nunn</span></span>
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<p>Traditional knowledge about insect behaviour in the Pacific Islands is also used to predict wet weather.</p>
<p>Bees, wasps and hornets usually build nests in tree branches. When nests are built close to the ground, Pacific Islanders know the forthcoming wet season will be wetter than normal, probably due to more tropical cyclones. This type of nest-building may <a href="https://doi.org/10.1080/17477891.2015.1046156">prompt</a> residents to make appropriate preparations such as storing food.</p>
<p>Studies suggest insect behaviour can predict changes in weather. For example, <a href="https://doi.org/10.1016/j.crvi.2009.10.007">a study</a> of wasp nesting in French Guiana found their ability to quickly move nests to more sheltered locations may help them survive wet years.</p>
<p>Across the Pacific, common signs of impending wet weather are found in the <a href="https://doi.org/10.1007/s10113-020-01613-w">behaviours</a> of <a href="https://doi.org/10.5751/ES-08100-210207">some plants</a>. The central shoot of the plantain, for example, will be conspicuously curled instead of straight.</p>
<p>This can be <a href="https://doi.org/10.1093/jxb/eru327">explained</a> scientifically by a process in which plant leaves close to protect their reproductive organs from extreme weather.</p>
<h2>Planning for a warmer future</h2>
<p>Since colonisation imposed Western worldviews around the world, traditional knowledge has been sidelined. This is true of the Pacific Islands, where in some places, traditional knowledge is all but <a href="https://theconversation.com/teaching-our-children-from-books-not-the-sea-how-climate-change-is-eroding-human-rights-in-vanuatu-192016">forgotten</a>. </p>
<p>But both Western and traditional knowledges have their pros and cons. Science-based knowledge, for example, is generic and often can’t realistically be applied <a href="https://theconversation.com/pacific-islands-must-stop-relying-on-foreign-aid-to-adapt-to-climate-change-because-the-money-wont-last-132095">at local scales</a>. </p>
<p>As climate change impacts worsen, optimal planning for island peoples should combine both approaches. This will require open-mindedness and a respect for diverse sources of knowledge.</p><img src="https://counter.theconversation.com/content/225088/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patrick D. Nunn receives funding from the Department of Foreign Affairs and Trade (DFAT) via the Australia Pacific Climate Partnership (APCP), the Australian Research Council, and the Asia-Pacific Network for Global Change Research.</span></em></p><p class="fine-print"><em><span>Roselyn Kumar receives funding from the Department of Foreign Affairs and Trade (DFAT) via the Australia Pacific Climate Partnership (APCP)</span></em></p>We reviewed evidence on traditional knowledge in the Pacific for coping with climate change, and found much of it was scientifically plausible.Patrick D. Nunn, Professor of Geography, School of Law and Society, University of the Sunshine CoastRoselyn Kumar, Adjunct Research Fellow in Geography and Social Sciences, University of the Sunshine CoastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2242842024-03-08T16:21:36Z2024-03-08T16:21:36ZRestored coral reefs can grow as fast as healthy reefs after just four years – new study<p>The coral reefs of south Sulawesi are some of the most diverse, colourful and vibrant in the world. At least, they used to be, until they were <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/rec.12866">decimated by dynamite fishing</a> in the 1990s. </p>
<p>As part of a team of coral reef ecologists based in Indonesia and the UK, we study the reefs around Pulau Bontosua, a small Indonesian island in south Sulawesi. Thirty years on, what were once large areas of thriving coral are now degraded sites are still devoid of colour, fish and other marine life. Broken skeletons of dead corals roll around on the seabed, crushing and killing any new coral larvae that try to settle and preventing the reefs from recovering naturally. </p>
<p>In many places around the world, damage like this might be described as irreparable. But at Pulau Bontosua, the story is different. Here, efforts by the <a href="https://www.buildingcoral.com/">Mars coral restoration programme</a> have brought back the coral and important ecosystem functions, as outlined by our new study, <a href="https://doi.org/10.1016/j.cub.2024.02.009">published in Current Biology</a>. We found that within just four years, restored reefs grow at the same rate as nearby healthy reefs. </p>
<p>The Mars coral restoration programme is one of the world’s largest restoration projects and has collaborated with local communities for more than a decade. Healthy coral fragments are attached to hexagonal, sand-covered steel frames called “reef stars”. These reef stars are installed on damaged reefs, where they stabilise the loose rubble, support growth of new coral and provide habitat for reef animals to move in.</p>
<h2>Speedy recovery</h2>
<p>The transplanted corals grow remarkably quickly. Within a year, fragments have developed into proper colonies. After two years, they interlock branches with their neighbours. After just four years, they completely overgrow the reef star structures and restoration sites are barely distinguishable from nearby healthy reefs.</p>
<p>The combined growth of many corals generates a complex limestone (calcium carbonate) framework. This provides habitat for marine life and protects nearby shorelines from storm damage by <a href="https://theconversation.com/coral-reefs-work-as-natures-sea-walls-it-pays-to-look-after-them-26655">absorbing up to 97% of coastal wave energy</a>. </p>
<p>We measured the overall growth of the reef framework by calculating its <a href="https://www.exeter.ac.uk/research/projects/geography/reefbudget/">carbonate budget</a>. That’s the balance between limestone production (by calcifying corals and coralline algae) and erosion (by grazing sea urchins and fishes, for example). A healthy reef produces up to 20kg reef structure per square metre per year, while a degraded reef is shrinking rather than growing, as erosion exceeds limestone production. Therefore, overall reef growth gives an indication of reef health.</p>
<p>At Pulau Bontosua, our survey data shows that in the years following restoration, coral cover, coral colony sizes and carbonate production rates tripled. Within four years, restored reefs were growing at the same speed as healthy reefs, and thereby provided the same important ecosystem functions.</p>
<p>This success is encouraging, but challenges still remain. The corals used to construct these restored reefs are predominantly branching coral types, chosen by the restoration team because they are easier to attach to the reef stars. This means that restored reefs have a lower diversity of coral types than healthy reefs, which host an abundance of boulder-like and encrusting corals as well as branching types. </p>
<p>These structural differences may affect the species of marine life that inhabit the reef. Branching corals are also notoriously sensitive to <a href="https://www.worldwildlife.org/pages/everything-you-need-to-know-about-coral-bleaching-and-how-we-can-stop-it">bleaching</a>, which happens when warmer water temperatures cause stress to corals and turn them white. Differences in the types of coral making up the reef ecosystem may therefore affect the reef’s ability to survive future heat waves. </p>
<h2>A warming world</h2>
<p>Marine heat waves are becoming <a href="https://theconversation.com/the-great-barrier-reef-has-been-bleaching-for-at-least-400-years-but-its-getting-worse-101691">more frequent and severe</a> and pose a huge threat to coral reefs and restoration efforts worldwide. Recently, thousands of <a href="https://theconversation.com/the-heroic-effort-to-save-floridas-coral-reef-from-extreme-ocean-heat-as-corals-bleach-across-the-caribbean-210974">nursery corals had to be rescued</a> when water temperatures spiked in the Florida Keys.</p>
<p>It’s imperative that coral reef restoration strategies include plans for warming waters. In some cases, efforts can be prioritised in areas where transplanted corals are less likely to encounter lethal conditions in the near future. In other cases, projects can enhance coral heat tolerance through <a href="https://theconversation.com/the-great-barrier-reef-can-repair-itself-with-a-little-help-from-science-85182">assisted evolution</a>. </p>
<p>There is some evidence that coral heat tolerance can also <a href="https://theconversation.com/remote-pacific-coral-reef-shows-at-least-some-ability-to-cope-with-ocean-warming-new-study-211852">increase naturally</a>. Whether this coral adaptation can keep pace with ocean warming will depend on global action to cut carbon emissions.</p>
<p>Outcomes of any reef restoration project will depend on environmental conditions, natural coral larvae supply, restoration techniques and the effort invested in maintaining the project. This Indonesian project shows that when conditions are right and efforts are well placed, success is possible. Hopefully, this inspires further global efforts to restore functioning coral reefs and to recreate a climate in which they can thrive.</p>
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<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">
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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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<hr><img src="https://counter.theconversation.com/content/224284/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ines Lange receives funding from the Bertarelli Program in Marine Science. Logistical research support for this study was provided by Mars Sustainable Solutions.</span></em></p><p class="fine-print"><em><span>Tim Lamont receives funding from the Royal Commission for the Exhibition of 1851, and the Fisheries Society of the British Isles. </span></em></p><p class="fine-print"><em><span>Tries Blandine Razak 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>Artificial reef stars have been added to damaged coral reefs in Sulawesi, Indonesia. A new study shows that within just four years, restored reefs are thriving as much as healthy reefs.Ines Lange, Senior Research Fellow in Coral Reef Ecology, University of ExeterTim Lamont, Research Fellow, Lancaster UniversityTries Blandine Razak, Researcher, IPB UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2242302024-03-07T19:03:24Z2024-03-07T19:03:24ZFished for their meat and liver oil, many remarkable deep-water sharks and rays now face extinction<figure><img src="https://images.theconversation.com/files/580260/original/file-20240306-24-da5war.jpg?ixlib=rb-1.1.0&rect=19%2C173%2C4262%2C2156&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/six-gill-shark-pup-110832647">Shutterstock/Greg Amptman</a></span></figcaption></figure><p>The deep ocean, beyond 200 metres of depth, is the largest and one of the most complex environments on the planet. It covers 84% of the world’s ocean area and 98% of its volume – and it is home to a great diversity of species.</p>
<p>Yet it remains among the least studied places on Earth, with no comprehensive assessments of the state of deep-water biodiversity and no policy-relevant indicators to guide the taking of species targeted by fisheries. </p>
<p>This also applies specifically to deep-water sharks and rays, even though these species make up nearly half of the recognised diversity of all cartilaginous fishes (sharks, rays, and chimaeras) we know today. </p>
<p>Our <a href="https://www.science.org/doi/10.1126/science.ade9121">research</a> highlights how our growing impact on the deep ocean raises the threat to these species. </p>
<p>Using the <a href="https://www.iucn.org/">International Union for Conservation of Nature</a> Red List of Threatened Species, we show that the number of threatened deep-water sharks and rays has more than doubled between 1980 and 2005, following the emergence and expansion of deep-water fishing. </p>
<p>We estimate one in seven species (14%) are threatened with extinction. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sharks-and-rays-are-in-free-fall-more-than-one-third-are-threatened-with-extinction-from-overfishing-167329">Sharks and rays are in free fall: More than one-third are threatened with extinction from overfishing</a>
</strong>
</em>
</p>
<hr>
<h2>Fishing for meat and oil</h2>
<p>Deep-water sharks and rays are in a group of marine vertebrates that are most sensitive to overexploitation. This is because of their long lifespans (possibly <a href="https://www.science.org/doi/full/10.1126/science.aaf1703">up to 450 years for the Greenland shark</a>, <em>Somniosus microcephalus</em>) and low reproduction rate (only <a href="https://www.iucnssg.org/publications-other.htmlhttps://www.iucnssg.org/publications-other.html">12 pups in a lifetime for the gulper shark</a>, <em>Centrophorus granulosus</em>). </p>
<p>These biological characteristics make them similar to formerly exploited, and now highly protected, marine mammals. </p>
<figure class="align-center ">
<img alt="Greenland shark in dark water" src="https://images.theconversation.com/files/580036/original/file-20240305-21577-2siggc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580036/original/file-20240305-21577-2siggc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580036/original/file-20240305-21577-2siggc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580036/original/file-20240305-21577-2siggc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580036/original/file-20240305-21577-2siggc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580036/original/file-20240305-21577-2siggc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580036/original/file-20240305-21577-2siggc.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">The Greenland shark can live up to 450 years.</span>
<span class="attribution"><a class="source" href="https://oceanservice.noaa.gov/facts/greenland-shark.html">Wikimedia Comons/Hemming1952</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>The Greenland shark and the leafscale gulper shark (<em>Centrophorus squamosus</em>), for example, have population growth rates comparable to the sperm whale (<em>Physeter macrocephalus</em>) and the walrus (<em>Odobenus rosmarus</em>), respectively. Despite their known inherent vulnerability, there are very few species-specific management actions for deep-water sharks. </p>
<p>Our research shows that overfishing is the primary threat to deep-water sharks and rays. They are used for their meat and liver oil, which drives targeted fisheries but also incidental capture, meaning any accidental catches are retained by fisheries targeting other species. </p>
<p>In many nations, deep-water sharks and rays are regarded as a welcome catch because of the <a href="https://saveourseas.com/update/is-by-catch-responsible-for-the-decline-of-deep-sea-oil-sharks/">high value of their liver oil</a> and <a href="https://academic.oup.com/icesjms/article/80/3/578/6484966">high demand for skate meat</a>. These are not new trades, but the global expansion and diversification of use, particularly for shark liver oil, is a relatively new phenomenon. </p>
<figure class="align-center ">
<img alt="Gulper shark" src="https://images.theconversation.com/files/580040/original/file-20240305-26-ioc67p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580040/original/file-20240305-26-ioc67p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580040/original/file-20240305-26-ioc67p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580040/original/file-20240305-26-ioc67p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580040/original/file-20240305-26-ioc67p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580040/original/file-20240305-26-ioc67p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580040/original/file-20240305-26-ioc67p.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">
<figcaption>
<span class="caption">Deep-water sharks, such as this gulper shark, are used for meat and liver oil.</span>
<span class="attribution"><a class="source" href="https://oceanexplorer.noaa.gov/okeanos/explorations/ex1811/logs/nov15/welcome.html">NOAA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Targeted shark liver oil fisheries are <a href="https://epubs.icar.org.in/index.php/IJF/article/view/92453">boom-and-bust fisheries</a>. They drive shark populations down and raise the extinction risk over short periods of time (less than 20 years). There is particular interest in shark liver oil for applications in cosmetics and human health products, including vaccine adjuvants. </p>
<p>This is despite a lack of evaluation of possible human health risks of using liver oil for medical purposes (deep-water sharks can bioaccumulate heavy metals and contaminants at concentrations at or above <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X23013772">regulatory thresholds</a>). </p>
<h2>Need for global deep-water shark action</h2>
<p>There have been tremendous triumphs in shark conservation, including the regulation of the global trade in fins from threatened coastal and pelagic species. But deep-water sharks have been largely left out of conservation discussions. </p>
<p>The <a href="https://cites.org/eng">Convention on International Trade in Endangered Species of Wild Fauna and Flora</a> has yet to see a listing proposal for a deep-water shark or ray. </p>
<figure class="align-center ">
<img alt="A deepwater stingray, Plesiobatis daviesi" src="https://images.theconversation.com/files/580257/original/file-20240306-28-9ocphi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580257/original/file-20240306-28-9ocphi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580257/original/file-20240306-28-9ocphi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580257/original/file-20240306-28-9ocphi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580257/original/file-20240306-28-9ocphi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580257/original/file-20240306-28-9ocphi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580257/original/file-20240306-28-9ocphi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Deep-water sharks and rays, such as this stingray, have been left out of conservation discussions.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Plesiobatis_daviesi_cochin.jpg#/media/File:Plesiobatis_daviesi_cochin.jpg">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We call for trade and fishing regulations specific to deep-water sharks and rays to ensure legal, traceable and sustainable trade and to prevent their further endangerment. </p>
<p>There are presently limited ways of determining which species comprise internationally traded liver oil. It may be a byproduct of sustainable fisheries but the current lack of regulations could also be masking the trade of threatened species. </p>
<p>We also propose closures of areas important to deep-water sharks and rays to provide refuge from fishing and promote recovery and long-term survival. Nearly every deep-water shark is threatened by incidental capture. </p>
<p><a href="https://ices-library.figshare.com/articles/report/Report_of_the_Working_Group_on_Elasmobranch_Fishes_WGEF_/24190332">Retention bans have been implemented</a> in some regions as a mitigation strategy, including European waters managed under the <a href="https://ices-library.figshare.com/">International Council for the Exploration of the Sea</a>. But they don’t prevent the mortality of prohibited species that are released after being brought to the surface from great depths. </p>
<p>We need efforts to prevent capture in the first place. There is now a global push to protect 30% of the ocean by 2030 through the <a href="https://www.cbd.int/gbf/targets">Convention on Biological Diversity</a>, which New Zealand has ratified. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/oceanic-sharks-and-rays-have-declined-by-71-since-1970-a-global-solution-is-needed-154102">Oceanic sharks and rays have declined by 71% since 1970 – a global solution is needed</a>
</strong>
</em>
</p>
<hr>
<p>Our work shows protecting 30% of the deep ocean (200-2000m) would provide around 80% of deep-water shark species with at least partial spatial protection across their range. If a worldwide prohibition of fishing below 800m were to be implemented, it would provide 30% vertical refuge for one third of threatened deep-water sharks and rays.</p>
<p>Even though the extinction risk for these species is much lower than that of their shallow-water relatives, their potential for recovery from overexploitation is much reduced because of their long lifespans and low fecundity. One <a href="https://academic.oup.com/icesjms/article/76/7/2318/5506076">study</a> estimated it would take 63 years or more for the little gulper shark (<em>Centrophorus uyato</em>) to recover to just 20% of its original population size. </p>
<p>We know many shark populations around the world <a href="https://www.cell.com/current-biology/pdf/S0960-9822(21)01198-2.pdf">are in trouble</a>. Threatened deep-water sharks have little chance of recovery without immediate action. Now is the time to implement effective conservation actions in the deep ocean to ensure half of the world’s sharks and rays have a refuge from the global extinction crisis.</p><img src="https://counter.theconversation.com/content/224230/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brittany Finucci is affiliated with the IUCN Species Survival Commission Shark Specialist Group.</span></em></p><p class="fine-print"><em><span>Cassandra Rigby is affiliated with the IUCN Species Survival Commission Shark Specialist Group.</span></em></p>Long lifespans and slow reproduction rates make deep-water sharks and rays as vulnerable to overexploitation as whales once were. We must place them under protection to avoid extinctions.Brittany Finucci, Fisheries Scientist, National Institute of Water and Atmospheric ResearchCassandra Rigby, Adjunct Senior Research Fellow, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2246072024-03-06T19:07:52Z2024-03-06T19:07:52ZSharks, turtles and other sea creatures face greater risk from industrial fishing than previously thought − we estimated added pressure from ‘dark’ fishing vessels<figure><img src="https://images.theconversation.com/files/580177/original/file-20240306-22-3smwaf.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C2977%2C1998&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Seabirds like this sooty shearwater can drown when they become tangled in drift nets and other fishing gear. </span> <span class="attribution"><a class="source" href="https://flic.kr/p/dj3H6v"> Roy Lowe, USFWS/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>My colleagues and I mapped activity in the northeast Pacific of “dark” fishing vessels – boats that turn off their location devices or lose signal for technical reasons. In <a href="https://www.science.org/doi/10.1126/sciadv.adl5528">our new study</a>, we found that highly mobile marine predators, such as sea lions, sharks and leatherback sea turtles, are significantly <a href="https://news.stanford.edu/2019/03/13/tunas-sharks-ships-sea/">more threatened than previously thought</a> because of large numbers of dark fishing vessels operating where these species live. </p>
<p>While we couldn’t directly watch the activities of each of these dark vessels, <a href="https://www.theguardian.com/environment/2022/nov/02/at-least-6-percent-global-fishing-likely-as-ships-turn-off-tracking-devices-study">new technological advances</a>, including satellite data and machine learning, make it possible to estimate where they go when they are not broadcasting their locations. </p>
<p>Examining five years of data from fishing vessel location devices and the habitats of 14 large marine species, including seabirds, sharks, turtles, sea lions and tunas, we found that our estimates of risk to these animals increased by nearly 25% when we accounted for the presence of dark vessels. For some individual predators, such as albacore and bluefin tunas, this adjustment increased risk by over 36%. The main hot spots were in the Bering Sea and along the Pacific coast of North America. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bjFSgr_B38I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bycatch, or accidental take, is the leading threat to some endangered marine species.</span></figcaption>
</figure>
<h2>How we did our work</h2>
<p>Fishing boats use <a href="https://globalfishingwatch.org/faqs/what-is-ais/">Automatic Identification System</a>, or AIS, to avoid colliding with each other. Their AIS signals bounce off satellites to reach nearby ships. </p>
<p>This data is a valuable tool for <a href="https://www.cbsnews.com/detroit/news/study-choosing-fish-may-be-killing-sharks/">mapping risk at sea</a> and <a href="https://www.bbc.com/news/science-environment-43169824">understanding the footprints of fishing fleets</a>. AIS data captures an estimated <a href="http://dx.doi.org/10.1126/science.aao564">50% to 80%</a> of fishing operations occurring more than 100 nautical miles from shore.</p>
<p>But in some areas, vessels’ AIS signals can’t reach the satellites, either because reception is poor or many boats are crowded together – much as cellphones can have difficulty sending text messages in remote wildness or in crowded stadiums. And just as location tracking can be disabled on phones, fishing vessels can intentionally <a href="https://theconversation.com/when-fishing-boats-go-dark-at-sea-theyre-often-committing-crimes-we-mapped-where-it-happens-196694">disable their AIS</a> if they want to hide their location. Boats that do this may be engaged in criminal activities, such as <a href="https://www.penguinrandomhouse.com/books/538736/the-outlaw-ocean-by-ian-urbina/">illegal fishing or human trafficking</a>.</p>
<p>We calculated how much risk dark vessels pose to marine life by overlapping their activity with the modeled habitats of 14 highly mobile marine predators. Using the same method, we also calculated how much risk observable fishing vessels that broadcast their locations pose to marine life. These two calculations allowed us to understand the additional risk from dark fishing vessels.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A seal on a beach, with a rope wrapped around it and connected to a large orange float beside the animal." src="https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579990/original/file-20240305-26-vf2vcl.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">A Hawaiian monk seal entangled on a large fishing float.</span>
<span class="attribution"><a class="source" href="https://photolib.noaa.gov/Collections/Fisheries/Other/emodule/1054/eitem/61324">Doug Helton, NOAA/NOS/ORR/ERD</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Why it matters</h2>
<p>We know that many sea creatures, including endangered species, are <a href="https://www.msc.org/en-us/what-we-are-doing/oceans-at-risk/overfishing">killed by overfishing</a>, <a href="https://www.latimes.com/opinion/op-ed/la-oe-welch-sea-turtles-swordfish-climate-change-20190610-story.html">accidental catch</a> and <a href="https://www.fisheries.noaa.gov/west-coast/marine-mammal-protection/west-coast-large-whale-entanglement-response-program">entanglement in fishing gear</a>. More overlap between wildlife and fishing boats means that those harmful impacts are more likely to happen. </p>
<p>Even considering only <a href="https://globalfishingwatch.org/map/index?start=2023-11-25T00%3A00%3A00.000Z&end=2024-02-25T00%3A00%3A00.000Z&latitude=19&longitude=26&zoom=1.5">observable fishing boats broadcasting their positions</a>, the presence of boats signals considerable risk for marine life. For example, <a href="https://www.fisheries.noaa.gov/species/california-sea-lion">California sea lions</a> forage in Pacific coastal waters from the Canadian border to Baja California and are accidentally caught by boats fishing for hake and halibut. We found observable fishing activity in over 45% of the sea lions’ habitat. </p>
<p>In another example, migratory <a href="https://www.adfg.alaska.gov/index.cfm?adfg=salmonshark.main">salmon sharks</a> feed on salmon near Alaska’s Aleutian Islands during the summer and breed in warmer waters off the coasts of Oregon and California during the winter. Along their journey, salmon sharks are accidentally caught in fishing nets and longlines. We detected observable vessel fishing activity in nearly one-third of salmon shark habitat. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.jpg?ixlib=rb-1.1.0&rect=31%2C0%2C5169%2C3461&q=45&auto=format&w=1000&fit=clip"><img alt="Dozens of fishing boats move out of an urban harbor" src="https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.jpg?ixlib=rb-1.1.0&rect=31%2C0%2C5169%2C3461&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579983/original/file-20240305-28-en5un3.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">Fishing boats head out for the East China Sea in Zhoushan, Zhejiang Province, China.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/fishing-boats-set-sail-in-the-morning-to-east-china-sea-for-news-photo/1340823231">Shen Lei/VCG via Getty Images</a></span>
</figcaption>
</figure>
<p>Our findings indicate that such threats are higher when dark fishing boats are present. Estimates of risk to California sea lions and salmon sharks increased by 28% and 23%, respectively, when we accounted for dark vessels.</p>
<p>This information could affect fishery regulation. For example, regulators <a href="https://www.fisheries.noaa.gov/feature-story/fish-stock-assessment-101-part-2-closer-look-stock-assessment-models">use risk information</a> to set catch limits for species such as tuna; higher risk could mean that catch limits need to be lower. </p>
<p>For species such as sea lions and salmon sharks that are accidentally caught by fishermen, higher risk levels could indicate that fishing boats should use more selective gear. California is currently acting on this issue by helping fishermen phase out use of <a href="https://opc.ca.gov/2022/11/phase-out-drift-gillnets/">large-mesh drift gill nets</a> in state waters. These nets, which hang like curtains in the water, catch <a href="https://www.fao.org/3/T0502E/T0502E01.htm">many other fishes along with the target species</a>. </p>
<p>Accounting for dark vessels is particularly important in international waters where boats from multiple countries operate, because AIS data is one of the most complete sources of fishing activity across nations. Tracking dark vessels can help make this information as comprehensive as possible and provide insights into the multinational impacts of fishing. </p>
<p>Our study does not account for vessels that do not use any vessel tracking system, or that use systems other than AIS. Therefore, our risk calculations likely still underestimate the true impact of fisheries on marine predators. </p>
<h2>What’s next</h2>
<p>The world’s oceans are rich in life but poor in data, although this is changing. High-resolution <a href="https://www.smithsonianmag.com/smart-news/satellite-maps-reveal-rampant-fishing-untracked-dark-vessels-oceans-180983539/">satellite imagery</a> may soon offer even more information on risk from dark vessels. </p>
<p>President Joe Biden and other global leaders have pledged to protect <a href="https://www.whitehouse.gov/briefing-room/statements-releases/2023/03/21/fact-sheet-biden-harris-administration-takes-new-action-to-conserve-and-restore-americas-lands-and-waters/">30% of the ocean by 2030</a>. Better data on human-wildlife interactions at sea can help ensure that new protected areas are in the right places to make a difference.</p><img src="https://counter.theconversation.com/content/224607/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Heather Welch receives funding from NOAA's Office of Law Enforcement. </span></em></p>The toll on wildlife from illegal fishing, bycatch and entanglement in fishing gear is likely underestimated, because it doesn’t account for ‘dark’ fishing vessels, a new study finds.Heather Welch, Researcher in Ecosystem Dynamics, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2247052024-03-06T17:15:02Z2024-03-06T17:15:02ZFive hotspots where floating plastic litter poses the greatest risk to North Atlantic marine life – new study<figure><img src="https://images.theconversation.com/files/579868/original/file-20240305-15007-nfvgpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">So much ocean plastic originates from sources on land, but once floating in the sea it poses a risk to marine wildlife and habitats. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/plastic-rubbish-pollution-ocean-environment-427946419">Rich Carey/Shutterstock</a></span></figcaption></figure><p>Plastic has been found in every single part of the ocean, from the surface to the seafloor and from the <a href="https://www.nature.com/articles/536263a">tropics to the poles</a>. Land-based sources of plastic account for the <a href="https://www.science.org/doi/10.1126/science.1260352">majority of this pollution</a>, with plastic bags, bottles, wrappers, food containers and cutlery among the most <a href="https://www.sciencedirect.com/science/article/pii/S0959378021001394">common items found</a>. </p>
<p>These items are often buoyant and float on the sea surface. As they travel long distances, they get pushed by the <a href="https://www.frontiersin.org/articles/10.3389/fmars.2021.697430/full">wind, waves and currents</a>. This means they have the potential to cause harm far beyond the country from <a href="https://www.frontiersin.org/articles/10.3389/fmars.2021.762235/full">which they originated</a>. For example, land-based plastic waste from Indonesia has been shown to travel over <a href="https://www.sciencedirect.com/science/article/pii/S0025326X22011791">4,000km to the Seychelles</a>.</p>
<p>As it travels, plastic litter can cause harm to wildlife. Megafauna (large marine animals) can <a href="https://link.springer.com/chapter/10.1007/978-3-319-16510-3_4#:%7E:text=Entangled%20biota%20are%20hindered%20in,1985%3B%20Laist%201997">eat or become entangled in it</a>. Consuming plastic litter can <a href="https://www.iucn.org/resources/issues-brief/marine-plastic-pollution">block or damage</a> the gastrointestinal tract of animals, causing significant health impacts or death. </p>
<p>While ghost fishing gear (lost fishing nets that float freely) is the most common entanglement threat to <a href="https://www.sciencedirect.com/science/article/pii/S0025326X16304386">marine megafauna</a>, they can also become <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X17300127">entangled</a> in land-sourced plastics such as plastic bags, frisbees, potato nets, elastic bands and other <a href="https://www.mdpi.com/2673-1924/3/3/26#:%7E:text=The%20current%20study%20summarizes%20data,quadrupled%20compared%20with%20previous%20studies.">circular plastics</a>. This can cause severe trauma to the animal, and in some cases <a href="https://www.sciencedirect.com/science/article/pii/S0025326X23007609?via%3Dihub">entanglement causes death</a>. </p>
<p>If plastic is transported towards the shore, it can get caught or lodged in shallow environments where it can entangle or cover plant or animal habitats, <a href="https://portlandpress.com/emergtoplifesci/article/6/4/371/231922/Plastic-pollution-of-four-understudied-marine">causing damage</a>. Plastic entanglement can cause breakage, and if it covers a habitat it will restrict access to food or light. </p>
<p>At <a href="https://www.pml.ac.uk/">Plymouth Marine Laboratory</a>, our team of marine researchers have developed a risk assessment approach to understand where this plastic litter could cause the most harm in the North Atlantic, and which countries that plastic originated from. Our research highlighted five areas of high risk – the US Atlantic, the US Gulf of Mexico, the UK, French Atlantic and Portuguese Azores.</p>
<h2>Reducing risk</h2>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0048969724014219#bb0890">In our new study</a>, we assessed the risk of land-sourced plastic litter to marine megafauna. That includes seabirds, whales and dolphins, seals and sea lions, manatees and dugongs, sharks and rays, tuna and billfish. We also assessed the risk to shallow water habitats including coral reefs, mangroves, seagrass beds, saltmarsh and kelp seaweed beds.</p>
<p>Using a particle tracking model, we tracked the flow of buoyant plastic litter released from the rivers of 16 countries bordering the North Atlantic between 2000 and 2015 using the most <a href="https://www.science.org/doi/10.1126/sciadv.aaz5803">recent data available</a>. Billions of virtual particles were released at the mouths of the rivers each month, with surface currents and wind used to drive their movement. After 15 years of tracking, our model showed us where plastic was likely to accumulate.</p>
<p>We also assessed the vulnerability of each of the megafauna groups and shallow water habitats to this plastic. For marine megafauna, we developed vulnerability scores by quantifying the amount of scientific evidence of ingestion or entanglement in land-sourced plastic. For habitats, we developed vulnerability scores by quantifying the scientific evidence available for this plastic causing harm by entanglement or smothering. </p>
<figure class="align-center ">
<img alt="Blue sea, green turtle swimming with fishing net attached behind it" src="https://images.theconversation.com/files/579866/original/file-20240305-16-gp5lsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579866/original/file-20240305-16-gp5lsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579866/original/file-20240305-16-gp5lsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579866/original/file-20240305-16-gp5lsb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579866/original/file-20240305-16-gp5lsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579866/original/file-20240305-16-gp5lsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579866/original/file-20240305-16-gp5lsb.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">Marine wildlife such as this green sea turtle can become entangled in ghost fishing gear that is left floating in the sea.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/green-sea-turtle-entangled-discarded-fishing-1688232751">Mohamed Abdulraheem/Shutterstock</a></span>
</figcaption>
</figure>
<p>To assess risk, we mapped the vulnerability and distribution of each megafauna group or habitat against the abundance of plastic. Each point within the map was given a risk score from zero to five. The greatest risk occurred in areas where high numbers of vulnerable megafauna or habitats overlapped with high concentrations of plastic.</p>
<h2>Managing the plastic problem</h2>
<p>We found that much of the modelled plastic litter causing risk in the UK originated from UK rivers. In other high-risk zones such as the Azores and the US Gulf of Mexico, plastic primarily originated from other regions. More than 99% of plastic litter in the Azores was estimated to come from the other countries, mainly Caribbean islands and the US. </p>
<p>The potential of this plastic to travel vast distances across the ocean makes management of this pollutant <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/reel.12257">particularly difficult</a>. More than 90% of plastic waste in the Dominican Republic and Haiti are <a href="https://publications.iadb.org/en/publications/english/viewer/Plastic-Waste-Management-and-Leakage-in-Latin-America-and-the-Caribbean.pdf">estimated to be mismanaged</a>. This waste has the potential to cause ecological harm across both sides of the Atlantic. </p>
<p>UN member nations have agreed to forge an international legally binding agreement to tackle plastic pollution, called the <a href="https://www.un.org/en/climatechange/nations-agree-end-plastic-pollution">Global Plastics Treaty</a>, with negotiations expected to be completed by the end of this year. This study highlights the importance of the treaty in ensuring international cooperation to reduce plastic consumption and waste, including the provision of financial support to help lower-income nations such as the Caribbean islands implement measures. Identification of high-risk zones will also help prioritise areas where interventions and monitoring should be targeted.</p>
<p>Even if all plastic intervention measures are implemented, it is likely that substantial amounts of plastic will still <a href="https://www.science.org/doi/10.1126/science.aba9475">enter our oceans</a>. The production, sale and distribution of many of single-use items are likely to be phased out under the <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/43239/ZERODRAFT.pdf">Global Plastics Treaty</a>, as nations move to restrict avoidable plastic products. </p>
<p>While global measures are hugely important in the fight against plastic, the choices of consumers also play a significant role. Reducing, re-using and recycling plastic are powerful ways to cut your plastic footprint. At both ends of the spectrum, the choices made at international and household level can be good news for marine wildlife.</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>
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<p class="fine-print"><em><span>Samantha Garrard receives funding from the Natural Environment Research Council and the Economic and Social Research Council</span></em></p>As it travels around the ocean, plastic litter can harm wildlife and marine habitats in many ways. This study highlights five key hotspots where floating plastic poses the biggest risk.Samantha Garrard, Senior Marine Ecosystem Services Researcher, Plymouth Marine LaboratoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2249542024-03-05T05:07:21Z2024-03-05T05:07:21ZMH370 disappearance 10 years on: can we still find it?<p>It has been ten years since Malaysia Airlines passenger flight MH370 <a href="https://theconversation.com/lessons-to-learn-despite-another-report-on-missing-flight-mh370-and-still-no-explanation-100764">disappeared on March 8 2014</a>. To this day it remains one of the biggest aviation mysteries globally.</p>
<p>It’s unthinkable that a modern Boeing 777-200ER jetliner with 239 people on board can simply vanish without any explanation. Yet multiple searches in the past decade have still not yielded the main wreckage or the bodies of the victims.</p>
<p>At a remembrance event held earlier this week, the Malaysian transport minister announced <a href="https://www.reuters.com/world/asia-pacific/malaysia-says-mh370-search-must-go-10-years-after-plane-vanished-2024-03-03/">a renewed push for another search</a>.</p>
<p>If approved by the Malaysian government, the survey will be conducted by United States seabed exploration firm Ocean Infinity, whose efforts were unsuccessful in 2018. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lessons-to-learn-despite-another-report-on-missing-flight-mh370-and-still-no-explanation-100764">Lessons to learn, despite another report on missing flight MH370 and still no explanation</a>
</strong>
</em>
</p>
<hr>
<h2>What happened to MH370?</h2>
<p>The flight was scheduled to fly from Kuala Lumpur to Beijing. Air traffic control lost contact with the aircraft within 60 minutes into the flight over the South China Sea.</p>
<p>Subsequently, it was tracked by military radar crossing the Malay Peninsula and was last located by radar over the Andaman Sea in the northeastern Indian Ocean.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of the region showing the initial search areas on 8-16 March." src="https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579774/original/file-20240305-18-vdbysn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&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 planned route, final route and initial search area for MH370 in Southeast Asia.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Timeline_of_Malaysia_Airlines_Flight_370#/media/File:MH370_initial_search_Southeast_Asia.svg">Andrew Heenen/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Later, automated satellite communications between the aircraft and British firm’s Inmarsat telecommunications satellite indicated that the plane ended up in the southeast Indian Ocean <a href="https://hub.arcgis.com/datasets/4c94d33cfc144f7d8b78943dee56e29b/explore">along the 7th arc</a> (an arc is a series of coordinates).</p>
<p>This became the basis for defining the initial search areas by the Australian Air Transport Safety Bureau. Initial air searches were conducted in the South China Sea and the Andaman Sea.</p>
<p>To date, we still don’t know what caused the aircraft’s change of course and disappearance.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579749/original/file-20240305-25-p456o1.png?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">Location of the 7th arc and the origin of debris locations for simulations undertaken by the University of Western Australia.</span>
<span class="attribution"><span class="source">Google Earth/Author provided</span></span>
</figcaption>
</figure>
<h2>What have searches for MH370 found so far?</h2>
<p>On March 18 2014, ten days after the disappearance of MH370, a search in the southern Indian Ocean <a href="https://www.atsb.gov.au/publications/2014/considerations-on-defining-the-search-area-mh370">was led by Australia</a>, with participation of aircraft from several countries. This search continued until April 28 and covered an area of 4,500,000 square kilometres of ocean. No debris was found. </p>
<p>Two underwater searches of the Indian Ocean, 2,800km off the coast of Western Australia, have also failed to find any evidence of the main crash site. </p>
<p>The initial seabed search, led by Australia, covered 120,000 square kilometres and extended 50 nautical miles across the 7th arc. It took 1,046 days and was suspended on January 17 2017.</p>
<p>A second search by Ocean Infinity in 2018 <a href="https://oceaninfinity.com/conclusion-of-current-search-for-malaysian-airlines-flight-mh370/">covered over 112,000 square kilometres</a>. It was completed in just over three months but also didn’t locate the wreckage.</p>
<h2>What about debris?</h2>
<p>While the main crash site still hasn’t been found, several pieces of debris have washed up in the years since the flight’s disappearance. </p>
<p>In fact, in June 2015 officials from the Australian Air Transport Safety Bureau determined that debris might arrive in Sumatra, contrary to the ocean currents in the region.</p>
<p>The strongest current in the Indian Ocean is the South Equatorial Current. It flows east to west between northern Australia and Madagascar, and debris would be able to cross it. </p>
<p>Indeed, on July 30 2015 a large piece of debris – a <a href="https://en.wikipedia.org/wiki/Flaperon">flaperon</a> (moving part of a plane wing) – washed up on Reunion Island in the western Indian Ocean. It was later confirmed to belong to MH370.</p>
<p>Twelve months earlier, using an oceanographic drift model, our University of Western Australia (UWA) modelling team had predicted that any debris originating from the 7th arc would end up in the western Indian Ocean.</p>
<p>In subsequent months, additional aircraft debris was found in the western Indian Ocean in Mauritius, Tanzania, Rodrigues, Madagascar, Mozambique and South Africa.</p>
<p>The UWA drift analysis accurately predicted where floating debris from MH370 would beach in the western Indian Ocean. It also guided American adventurer Blaine Gibson and others to directly recover several dozen pieces of debris, three of which <a href="https://www.newsweek.com/where-blaine-gibson-now-malaysia-airlines-mh370-debris-hunter-1787369">have been confirmed</a> to be from MH370, while several others <a href="https://www.airlineratings.com/news/mh370-debris-now-for-the-facts/">are deemed likely</a>.</p>
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<a href="https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A detailed satellite map showing locations of debris found on the shores of Africa and Madagascar." src="https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=757&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=757&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579756/original/file-20240305-22-q62h9n.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=757&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">Predicted locations of landfall from results of University of Western Australia drift modelling. The white dots indicate predicted landfall of the debris. The aggregation of many dots, particularly close to land, is an indication of the density of particles – higher probability of debris making landfall. These are highlighted by red circles.</span>
<span class="attribution"><span class="source">Charitha Pattiaratchi/UWA, Author provided</span></span>
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<p>To date, these debris finds in the western Indian ocean are the only physical evidence found related to MH370.</p>
<p>It is also independent verification that the crash occurred close to the 7th arc, as any debris would initially flow northwards and then to the west, transported by the prevailing ocean currents. These results are consistent with other drift studies undertaken by independent researchers globally.</p>
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Read more:
<a href="https://theconversation.com/ocean-currents-suggest-where-we-should-be-looking-for-missing-flight-mh370-63100">Ocean currents suggest where we should be looking for missing flight MH370</a>
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<h2>Why a new search for MH370 now?</h2>
<p>Unfortunately, the ocean is a chaotic place, and even oceanographic drift models cannot pinpoint the exact location of the crash site.</p>
<p>The proposed new search by Ocean Infinity has significantly narrowed down the target area within latitudes 36°S and 33°S. This is approximately 50km to the south of the locations where UWA modelling indicated the release of debris along the 7th arc. If the search does not locate the wreckage, it could be extended north.</p>
<p>Since the initial underwater searches, technology has tremendously improved. Ocean Infinity is using a fleet of autonomous underwater vehicles with improved resolution. The proposed search will also use remotely controlled surface vessels.</p>
<p>In the area where the search is to take place, the ocean is around 4,000 metres deep. The water temperatures are 1–2°C, with low currents. This means that even after ten years, the debris field would be relatively intact.</p>
<p>Therefore, there is a high probability that the wreckage can still be found. If a future search is successful, this would bring closure not just to the families of those who perished, but also the thousands of people who have been involved in the search efforts.</p>
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Read more:
<a href="https://theconversation.com/mh370-new-underwater-sound-wave-analysis-suggests-alternative-travel-route-and-new-impact-locations-110664">MH370: New underwater sound wave analysis suggests alternative travel route and new impact locations</a>
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<p class="fine-print"><em><span>Charitha Pattiaratchi receives funding from Integrated Marine Observing System research institute, the Australian Research Council and the West Australian Marine Science Institution.</span></em></p>It remains one of the biggest aviation mysteries – the tragic disappearance of passenger flight MH370. But a new, targeted search of the seabed could still yield answers.Charitha Pattiaratchi, Professor of Coastal Oceanography, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2248842024-03-04T16:54:22Z2024-03-04T16:54:22ZDiscovering the world of dolphins and their three ‘super senses’<figure><img src="https://images.theconversation.com/files/579179/original/file-20240129-15-onehyv.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C4265%2C2826&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dolphins can communicate very effectively.</span> <span class="attribution"><a class="source" href="https://unsplash.com/fr/photos/photographie-en-accelere-de-deux-dauphins-nageant-dans-la-mer-ZYPQDN_xSqk">Arielle Allouche/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Imagine that you’re in a comfortable room with your cat. You’re both sharing the same space, temperature and lighting. But while you’re enjoying the décor, and perhaps a book or the taste of hot chocolate, the cat seems intrigued by something else. Maybe she’s looking for a treat or making sure that no one infringes on “her” preferred spot, a comfortable armchair near the heater.</p>
<p>All this is to say that even if you and your pet are in the same place, you both perceive your environment differently. In 1934, the German scientist Jakob von Uexküll defined it as the “umwelt” (<em>environment</em> in German). The <em>umwelt</em> is each individual’s <a href="https://monoskop.org/images/1/1d/Uexkuell_Jakob_von_A_Stroll_Through_the_Worlds_of_Animals_and_Men_A_Picture_Book_of_Invisible_Worlds.pdf">perception of the world in which he or she lives</a>.</p>
<p>But how do other animals perceive the world around them? I’m particularly interested in those that live in habitats that are drastically different from those of humans, such as dolphins in the vastness of the ocean.</p>
<p>By understanding animals’ perceptions, we can better protect them. In the case of dolphins, knowing how they perceive their environment means knowing the impact of underwater noise on their communication and taking measures to control it in protected marine areas.</p>
<p>So let’s dive in and discover the three super-senses of dolphins: magnetic perception, electrical perception and echolocation.</p>
<h2>Magnetic perception</h2>
<p>Magnetic perception was first demonstrated in dolphins in 1981: American researchers found <a href="http://www.ncbi.nlm.nih.gov/pubmed/7256282">fragments of magnetite closely linked to neuronal connections</a> extracted from the brains of four stranded common dolphins. Surprised by the discovery, the scientists suggested that it could have a sensory function or play a role in navigation.</p>
<p>In 1985, another team of researchers discovered a <a href="https://journals.biologists.com/jeb/article/120/1/1/4953/Evidence-From-Strandings-for-Geomagnetic">relationship between cetacean stranding positions and the Earth’s geomagnetic field</a>: several species of whales and dolphins actually tend to strand in places where the magnetic intensity is low. If cetaceans use the Earth’s magnetic field to find their bearings, one hypothesis is that areas where the magnetic intensity is weaker would increase the likelihood of stranding due to a lack of bearings.</p>
<p>In 2014, with a team of scientists from the University of Rennes 1, I carried out a behavioural study that enabled us to show that <a href="https://hal.science/hal-01134557">bottlenose dolphins have a magnetic sense</a>. We tested the spontaneous response of six captive dolphins to the presentation of two objects with the same shape and density: the first contained a block of magnetically charged neodymium (a metal), while the second device was completely demagnetised.</p>
<p>The dolphins approached the device much more quickly when it contained a block of strongly magnetised neodymium. This allowed us to conclude that the dolphins are able to discriminate between the two stimuli on the basis of their magnetic properties.</p>
<p>These data support the hypothesis that cetaceans can determine their location using the Earth’s magnetic field and that, consequently, when this field is weaker, the tendency to strand is greater.</p>
<h2>Electrical perception</h2>
<p>When fish move their muscles and skeletons, they emit weak electric fields. Some marine predators, particularly in benthic areas (at the bottom of the ocean) – where visibility is reduced, are able to perceive their prey via these electric fields. A range of aquatic and semi-aquatic species share this ability.</p>
<p>In dolphins, electroreception was demonstrated for the first time in 2012. The structures known as hairless <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2011.1127">vibrissal crypts</a> on the rostrum of Guiana dolphins (one of the smallest species) serve as electroreceptors. In the study, the researchers noted that the vibrissal crypts have a well-innervated ampullary structure, reminiscent of the ampullary electro-receptors in other species such as <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/elasmobranch">elasmobranchs</a> (sharks and rays), lampreys, paddlefish, catfish, certain amphibians and even in the platypus and echidna). These vibrissal crypts are thought to function as sensory receptors capable of picking up small electric fields emitted by prey in aquatic environments.</p>
<p>The same study also found behavioural evidence of electroperception. A male Guiana dolphin was trained to respond to electrical stimuli of the order of magnitude of those generated by small-to medium-sized fish. For example, a goldfish 5 to 6 centimetres long produces electric fields of 90 microvolts per centimetre, with a peak energy at 3 hertz. Bioelectric fields of 1,000 microvolts per centimetre have been reported in flounders – a magnitude equivalent to 1/100,000 of the electric current of a light bulb.</p>
<p>The dolphin was trained to place its head in a hoop and touch a target with the tip of its rostrum. It had to leave the hoop when a stimulus was presented, and when no stimulus was presented, it had to remain in the hoop for at least 12 seconds.</p>
<p>This experiment showed that dolphins perceive weak electric fields – a sensitivity comparable to that of platypus electroreceptors. The first clear demonstration of electroreception in platypuses was carried out in Canberra in 1985 by a German-Australian team, which showed that <a href="https://www.nature.com/articles/319401a0">they sought out and attacked submerged and otherwise invisible batteries</a>. In 2023, a team of researchers found similar <a href="https://pubmed.ncbi.nlm.nih.gov/38035544/">detection thresholds in bottlenose dolphins</a>, using the same behavioural test.</p>
<p>It is now thought that electroreception can facilitate the detection of prey at close range and the targeted killing of prey on the seabed.</p>
<p>In addition, the ability to detect weak electric fields could enable dolphins to perceive the Earth’s magnetic field by means of magnetoreception, which could enable them to orientate themselves on a large scale.</p>
<h2>Echolocation</h2>
<p>The most studied sense in dolphins remains <a href="https://www.frontiersin.org/articles/10.3389/fevo.2016.00049/full">echolocation</a>.</p>
<p>A more active sense than the detection of electric or magnetic fields, echolocation involves the dolphins producing sequences of clicks with their phonic lips (located in the blowhole, the nostril on the dolphin’s head). The clicks produced are highly directional, moving forward. When the sound wave touches a surface, it returns and is perceived through the dolphin’s lower jaw. In this way, they perceive sound waves extremely well, without having external ears and so retaining their smooth hydrodynamic shape.</p>
<p>Thanks to this information, the dolphin can not only know the location of a target, but also deduce its density: a dolphin can distinguish at a distance of 75 metres whether a one-inch diameter sphere (2.54 cm) is made of <a href="https://pubs.aip.org/asa/jasa/article-abstract/68/4/1077/625152/Long-range-target-detection-in-open-waters-by-an">solid steel or filled with water</a>.</p>
<h2>Dolphins communicate through channels that are inaccessible to us</h2>
<p>Dolphins’ impressive ability to “see with their ears” doesn’t stop there. Dolphins can listen to the echoes of clicks produced by their fellow dolphins, an ability known as “eavesdropping”](https://link.springer.com/article/10.3758/BF03199007). In this way, they can “share” what they detect with the members of their group and coordinate their movements.</p>
<p>As part of my research, I was interested in <a href="https://go.gale.com/ps/i.do?id=GALE%7CA491087577">how dolphins use their clicks to synchronise their movements</a>. To do this, I exploited a <a href="https://www.aquaticmammalsjournal.org/article/vol-43-iss-2-lopez-marulanda/">recording method using four hydrophones and a 360° camera</a>, which make it possible to know which dolphin is making a sound – something that was previously impossible because dolphins do not open their mouths to vocalise.</p>
<p>I was able to show that <a href="https://www.sciencedirect.com/science/article/abs/pii/S0376635721000449">when the dolphins jump synchronously in a dolphinarium, one produces the clicks while the others remain silent</a>. In our experiment, we determined that the animal that produced the clicks was always the oldest female.</p>
<p>Will the same thing happen in the wild when dolphins fish in coordination? To find out, we would need to use the same 360° audiovisual recording method in the ocean. This would involve establishing an observation base in a feeding area with good visibility – for example, when dolphins are feeding around fish farms. The regular proximity of the dolphins would make it possible to record their solitary fishing behaviour, and to better understand how they cooperate and coordinate, using all of their three “super senses”.</p><img src="https://counter.theconversation.com/content/224884/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Juliana López Marulanda is co-founder of the Macuaticos Colombia Foundation for the research and conservation of cetaceans in Colombia.</span></em></p>Let’s delve into the three super-senses of dolphins: magnetic perception, electrical perception and echolocation.Juliana López Marulanda, Enseignante chercheuse en éthologie, Université Paris Nanterre – Université Paris LumièresLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2245812024-02-28T22:31:32Z2024-02-28T22:31:32ZHow climate change is messing up the ocean’s biological clock, with unknown long-term consequences<figure><img src="https://images.theconversation.com/files/578761/original/file-20240228-30-1ljbi.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3199%2C2400&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A satellite image of a phytoplankton bloom off the coast of St. John's, N.L.</span> <span class="attribution"><span class="source">(NASA, MODIS Rapid Response)</span></span></figcaption></figure><p>Every year in the <a href="https://www.ncesc.com/geographic-faq/what-is-the-middle-and-lower-latitude/">mid-latitudes</a> of the planet, a peculiar phenomenon known as the <a href="https://earthobservatory.nasa.gov/features/Phytoplankton">phytoplankton</a> <a href="https://doi.org/10.1111/gcb.13858">spring bloom</a> occurs. Visible from space, spectacular large and ephemeral filament-like shades of green and blue are <a href="https://doi.org/10.1029/2012GL052756">shaped by the ocean currents</a>.</p>
<p>The phytoplankton blooms are comprised of a myriad of microscopic algae cells growing and accumulating at the ocean’s surface as a result of the onset of longer days and fewer storms — often associated with the move into spring.</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>The timing of the phytoplankton spring bloom is, however, <a href="https://doi.org/10.1111/gcb.13886">likely to be altered</a> in response to climate change. Changes which will affect — for good or ill — the many species that are <a href="https://doi.org/10.1146/annurev-marine-052913-021325">ecologically adapted</a> to benefit from the enhanced feeding opportunity that blooms represent at crucial stages of their development.</p>
<h2>Fine-tuned ecological adaptation</h2>
<p>Phytoplankton blooms are, in some aspects, <a href="https://doi.org/10.1111/gcb.14650">metronomes of the annual oceanic cycles</a> around which many species’ biological clocks are synced to.</p>
<p>One example is the zooplankton <a href="https://zooplankton.nl/en/diversity/copepods/"><em>Calanus finmarchicus</em></a>, a class of micro-organism only capable of swimming up and down through the water column. <em>Calanus finmarchicus</em> usually spend the winter in <a href="https://doi.org/10.1146/annurev-marine-010816-060505">diapause</a> — the marine version of hibernation — surviving on their accumulated energy reserves in the deep ocean. At the moment they deem appropriate in the spring, they raise from the abyss to graze on the bloom and reproduce.</p>
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<a href="https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image of a Calanoid Copepod." src="https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.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">An image of an individual in the Calanoid Copepod group. The Calanoid Copepod is one of three groups of animals within the general category of Copepods, encompassing around 10,000 species. The Calanus finmarchicus is a member of the Calanoid Copepods group.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>Fish and shellfish, too, are adapted to this natural metronome. </p>
<p>For some species, such as shrimp, females strategically lay their eggs in the water in advance of these blooms so their young will have ample food supplies from the moment they hatch</p>
<p>As incredible as it seems, some species can “calculate” the egg incubation period so that eggs hatch on average <a href="https://doi.org/10.1126/science.1173951">within a week</a> of the expected spring bloom.</p>
<h2>A question of timing</h2>
<p>This, unfortunately, is where climate change is entering into the equation. What was normal in the past may well be changing more rapidly than marine species can adapt. </p>
<p>Zooplankton and fish larvae constitutes the bulk of what ocean scientists call secondary production. Secondary production is a <a href="https://doi.org/10.1139/f2012-050">key trophic level</a> that links primary production (the phytoplankton using the sun’s light to produce biomass) and higher trophic levels, such as fish and marine mammals.</p>
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<a href="https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite image of a phytoplankton bloom." src="https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=607&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=607&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=607&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=762&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=762&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=762&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">A massive phytoplankton bloom seen off the Northern coast of Norway. Phytoplankton blooms can reach thousands of square kilometres in size.</span>
<span class="attribution"><span class="source">(ESA, Envisat Pillars)</span></span>
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<p>This grand relationship is known as a <a href="https://doi.org/10.1016/j.tree.2016.08.010">trophic cascade</a>, as the zooplankton are eaten by the small fish and the small fish, in turn, are eaten by the bigger fish. A whole ecosystem beating on a clock largely determined by the timing of the phytoplankton spring bloom, hopefully in sync with the biological clocks of other species.</p>
<p>Any change to the timing of the spring bloom, for example as a result of climate change, can potentially have catastrophic consequences for the survival of zooplankton populations alongside the fishes and ecosystems which rely upon this abundant foodstuff. </p>
<p>This theory is known as the <a href="https://doi.org/10.1016/S0065-2881(08)60202-3">match/mismatch hypothesis</a> and postulates that the consumer’s energy demand should “match” the peak resource availability</p>
<h2>A new understanding</h2>
<p>On the Newfoundland and Labrador shelf in the Northwest Atlantic, the spring bloom <a href="https://doi.org/10.1002/jgrg.20102">generally starts</a> earlier in the south (mid-March on the Grand Banks of Newfoundland) and later in the north (late April on the southern Labrador shelf).</p>
<p>The south-to-north progression of the bloom was long believed to be related to the <a href="https://doi.org/10.1093/plankt/fbm035">annual retreat of sea ice</a> in the region.
But with the duration and spatial extent of the sea ice season being <a href="https://publications.gc.ca/collections/collection_2023/mpo-dfo/Fs97-6-3544-eng.pdf">dramatically reduced</a> in Atlantic Canada over the recent years, the relationship between sea ice and the timing of the bloom weakened.</p>
<p>I — alongside a team of researchers from across Canada — <a href="https://doi.org/10.1002/lol2.10347">proposed a new theory</a> to explain the initiation of the spring bloom on the Newfoundland and Labrador shelf. </p>
<p>Our theory points to transition from winter to spring as being key to trigger the bloom. In winter, cold and stormy conditions keep the ocean well mixed. However, the arrival of spring brings calmer winds and warming temperatures — coupled with increased freshwater flows. These conditions cause the ocean to reorganize into layers of different density — a phenomenon called <a href="https://doi.org/10.1093/plankt/fbv021">re-stratification</a>.</p>
<p>Re-stratification effectively prevents the phytoplankton cells of the upper layers from becoming easily mixed in the maelstrom of oceanic forces.
Their accumulation at the ocean’s surface creates the bloom.</p>
<p>This new mechanism successfully predicts the timing of the phytoplankton spring bloom over more than two decades. It also allows us to better understand the impacts that climate change is having upon our oceans.</p>
<h2>Ecological significance</h2>
<p>Located at the confluence of sub-arctic and sub-tropical ocean currents, the Newfoundland and Labrador shelf is naturally subjected to <a href="https://doi.org/10.5194/essd-13-1807-2021">large fluctuations</a> of its climate, with impacts on the timing of the bloom.</p>
<p>Our study has shown that a warmer climate is associated with earlier re-stratification, earlier phytoplankton blooms and a higher abundance of key zooplankton species such as <em>Calanus finmarchicus</em> in the region.</p>
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Read more:
<a href="https://theconversation.com/climate-change-is-further-reducing-fish-stocks-with-worrisome-implications-for-global-food-supplies-217428">Climate change is further reducing fish stocks with worrisome implications for global food supplies</a>
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<p>This discovery opens the door to a better understanding of bloom dynamics and the oceanic conditions driving the health of the ecosystem.</p>
<p>The good news for a cold region such as the Newfoundland and Labrador shelf is that a warmer climate with milder springs, like the ones we have <a href="https://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2022/2022_040-eng.html">seen in recent years</a>, will lead to more and more abundant levels of phytoplankton — with clear benefits to ecosystem productivity. </p>
<p>However, for how long these changes will remain positive in a changing climate we cannot say.</p><img src="https://counter.theconversation.com/content/224581/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frédéric Cyr 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>Recent research sheds light on the ocean’s annual ‘biological clock’ and highlights the key dynamics that make it susceptible to climate change.Frédéric Cyr, Adjunct Professor, Physical Oceanography, Memorial University of NewfoundlandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2239192024-02-21T19:01:08Z2024-02-21T19:01:08ZTracking tropical turtles deep down to the seabed reveals their feeding habits<p>Hawksbill turtles are <a href="https://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T8005A12881238.en">critically endangered</a>, they are found in every ocean and are the most tropical of sea turtles. Adult hawksbills have long been considered to have a close association with shallow (less than 15 metres depth) seas where coral reefs thrive.</p>
<p>But <a href="https://www.doi.org/10.1126/sciadv.adl2838">new research</a> my colleagues and I conducted reveals for the first time that hawksbill turtles feed at reef sites much deeper than previously thought. </p>
<p>Young hawksbills drift in currents during their pelagic (open water) phase of their development before they move to benthic (sea bed) habitats. Hawksbills are usually seen foraging in coral reefs where their diet is predominantly <a href="https://doi.org/10.3354/meps245249">sponges</a>. They also feed on a variety of algae, corallimorphs (coral-like anemones), tunicates and <a href="https://www.ajol.info/index.php/wiojms/article/view/66534">more</a>. </p>
<p>To study their feeding habits in more detail, my team at Swansea University used high-accuracy global positioning system (GPS) satellite tags to track 22 adult female hawksbills from their nesting site on Diego Garcia in the Chagos archipelago in the Indian Ocean to their foraging grounds. </p>
<p>Three of the tags included a pressure transducer that was programmed to record depth every five minutes and relay the measurement to the satellite system every time the turtle surfaced. This gave us information about the whereabouts of the turtles and how deep they were diving to feed as they swam.</p>
<p>We predicted that hawksbills tracked in our study would probably migrate to shallow coral reefs around the seven atolls of the Chagos archipelago. Many studies have shown the <a href="https://www.nature.com/articles/srep18289">pristine nature of these reefs</a> and we have previously observed hawksbills frequently foraging in reef habitats there. </p>
<p>But, surprisingly, all turtles migrated to deep, remote banks and submerged reefs in the archipelago, remaining at these deep sites for more than 6,000 combined days of tracking. By looking at nautical charts for the turtle locations, we could see that the foraging habitat was located at more than 30 metres depth. </p>
<p>More than 183,000 depth measurements relayed from the tags on three turtles showed that average depths were between 35 metres and 40 metres. <a href="https://doi.org/10.1126/sciadv.adl2838">Most dives reached depths between 30 metres and 60 metres</a>. That’s much deeper than we expected.</p>
<h2>Crucial for conservation</h2>
<p>The coral reefs located at depths of between 30 metres and 150 metres below the waves are known as mesophotic (or low light) ecosystems. Now, knowing that these habitats are so crucial for critically endangered sea turtles suggests that the marine life deep down on the seabed is much richer – with more nutritious food for turtles to eat – than previously thought. </p>
<p>We’d expect to find an abundance of colourful sponges and other invertebrate prey items such as soft corals that make up a big portion of the hawksbills’ diet. Our finding adds to the growing evidence that submerged banks at these mesophotic depths might be home to a diverse community of life, including <a href="https://www.ajol.info/index.php/wiojms/article/view/209266">sponges</a> and <a href="https://doi.org/10.1016/j.marpolbul.2018.03.018">seagrass</a> that are key foods for green turtles that also breed and forage in the western Indian Ocean. </p>
<p>Mesophotic ecosystems cover a vast area so they should be a significant part of conservation considerations. We estimated that submerged banks (at depths of 30 to 60 metres) in the western Indian Ocean extend across over 55,000 km² - around three times the size of a small country such as Wales.</p>
<p>Scientific understanding of mesophotic ecosystems is very poor, partly because they are difficult to explore. They are usually remote and far from land, plus the depths are often beyond the limit of routine scientific scuba diving. </p>
<p>There’s huge scope for more fascinating research to investigate the ecology of these misunderstood marine habitats. Recent studies have suggested <a href="https://doi.org/10.1371/journal.pone.0177374">rich biodiversity</a> and <a href="https://www.nature.com/articles/s41598-017-03568-1">abundant fish</a>, <a href="https://link.springer.com/article/10.1007/s00338-010-0593-6">corals and sponges</a> live at depths over 30 metres. </p>
<h2>Reef refuges</h2>
<p>With the pressures of climate change and warming seas, mesophotic reefs could be a refuge for corals and sponges that normally live in shallow coral reefs. For example, coral cover in Caribbean mesophotic reefs (30 to 40 metres depth) remained constant during hurricanes, bleaching and disease events in 2017 to 2019 when coral cover declined in shallow- and mid-water depths. That demonstrates the importance of these mesophotic reefs as a <a href="https://link.springer.com/article/10.1007/s00338-021-02087-w">reproductive refuge for corals</a>.</p>
<p>Our study findings highlight that submerged banks and mesophotic depths are important foraging grounds for critically endangered marine animals such as turtles and may support a rich array of marine life. While the mesophotic reefs used by foraging hawksbills in our study lie within one of the world’s largest marine protected areas, with <a href="https://doi.org/10.1007/s00227-020-03776-w">protection from industrial fishing</a>, there are ongoing negotiations for future conservation management of this region. </p>
<p>These submerged banks in the Chagos archipelago, and probably others around the world, should be key areas for conservation focus. The resilience of marine ecosystems, and all that lives within them, may rely on the health of these deeper, uncharted habitats, especially in the face of climate change.</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 class="fine-print"><em><span>Nicole Esteban receives funding from the Bertarelli Foundation as part of the Bertarelli Programme in Marine Science (grant numbers BPMS-2017-4 and 820633).</span></em></p>Deeper ocean habitats (30-150 metres) are a key feeding ground for critically endangered hawksbill turtles.Nicole Esteban, Associate Professor of Marine Biology, Swansea UniversityLicensed 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>
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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/2231712024-02-13T12:45:10Z2024-02-13T12:45:10ZStruggling seabirds thrown a lifeline by new commercial fishing ban in the North Sea – but it may not be enough<figure><img src="https://images.theconversation.com/files/574500/original/file-20240208-20-wgkkts.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Puffins and many other seabirds rely on sandeels as a food source. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/closeup-atlantic-puffin-fish-beak-1909632901">Arnoud Quanjer/Shutterstock</a></span></figcaption></figure><p>With their bright, orange feet and colourful beaks full of glistening fish, puffins are really charismatic seabirds. But <a href="https://jncc.gov.uk/our-work/seabirds-count/#results">puffin populations are in decline</a>, largely due to their struggle to catch enough of <a href="https://datazone.birdlife.org/species/factsheet/atlantic-puffin-fratercula-arctica/details">these shiny fish: sandeels</a>. </p>
<p>Sandeels have been industrially fished on an industrial scale <a href="https://academic.oup.com/icesjms/article/59/2/261/619635">since the 1950s</a>, not for human consumption but to make fishmeal. They are the bedrock of marine ecosystems in the <a href="https://consult.defra.gov.uk/wg-management-measures-for-industrial-sandeel-fishing/consultation-on-spatial-management-measures-for-in/supporting_documents/What%20are%20the%20ecosystem%20risks%20and%20benefits%20of%20full%20prohibition%20of%20industrial%20Sandeel%20fishing%20in%20the%20UK%20waters%20of%20the%20North%20Sea%20ICES%20Area%20IV.pdf">North Sea</a>. But a new fishing ban could provide welcome respite for puffins and other marine wildlife. </p>
<p>The UK and Scottish governments have announced a permanent end to industrial sandeel fishing in English and Scottish waters. <a href="https://blogs.gov.scot/marine-scotland/2024/01/31/sandeel-fishing-to-be-banned-in-scottish-waters/">This ban</a> will begin on April 1 – the start of this year’s sandeel fishing season. </p>
<p>The news of the closure of this sandeel fishery has been met with praise from across the conservation sector. A quarter of a century of <a href="https://www.rspb.org.uk/whats-happening/news/sandeel-campaign-success-in-england">campaigning by the RSPB</a> seems to have paid off. </p>
<p>The health of sandeel populations in Scottish and English seas can link to the breeding success of the seabirds that feed on them, but the correlation is complex. This fishing ban is a start but, with the added pressures of climate change, more is needed to save Britain’s seabirds.</p>
<h2>The significance of sandeels</h2>
<p>These small, silver, schooling fish pack a large nutritional punch. They feed on zooplankton and are a vital source of food for <a href="https://doi.org/10.1111/j.0022-1112.2004.00400.x">larger fish</a> such as cod, haddock and whiting, as well as <a href="https://doi.org/10.3354/meps08232">top predators such as seals</a>. </p>
<p>Sandeels are also a favourite food for seabirds such as surface-feeding gulls and terns, and deep-diving auk species including puffins, razorbills and guillemots.</p>
<p>As well as falling foul of marine predators, sandeels are caught by humans, largely to be used as <a href="https://doi.org/10.1093/icesjms/fst087">feed for farmed fish</a>, such as salmon, or livestock. The sandeel fishing grounds around the UK are jointly managed by the UK and the European Union. </p>
<p>But the UK government has not allowed British vessels to fish for sandeels <a href="https://www.gov.scot/publications/sandeel-prohibition-fishing-scotland-order-2024-final-business-regulatory-impact-assessment/">since 2021</a>. Instead, commercial fishing for sandeels has most recently been carried out by European vessels, <a href="https://www.gov.scot/publications/sandeel-prohibition-fishing-scotland-order-2024-final-business-regulatory-impact-assessment/">particularly those from Denmark</a> that regularly fish in UK waters during the summer. </p>
<p>Data from the Marine Management Organisation suggests that an average of <a href="https://www.gov.scot/publications/sandeel-prohibition-fishing-scotland-order-2024-final-business-regulatory-impact-assessment/">257,000 tonnes of sandeels</a> were caught annually by EU vessels between 2015 and 2019.</p>
<p>One of the major sandeel fishing areas in the North Sea, a 21,000km2 area off the east coast of Scotland and northeast England called <a href="https://marine.gov.scot/sma/assessment/case-study-sandeels-scottish-waters#:%7E:text=The%20largest%20of%20the%20sandeel,one%20with%20an%20active%20fishery.">sandeel area 4</a>, has been closed to both UK and EU vessels since 2000 – although a small scientific fishery continued to conduct stock assessments <a href="https://data.marine.gov.scot/dataset/monitoring-consequences-northwestern-north-sea-sandeel-fishery-closure">during this time</a>. </p>
<p>Following the area’s closure, sandeel numbers grew and that corresponded with an initial increase in the number of fledged chicks in <a href="https://doi.org/10.1139/f07-164">black-legged kittiwakes</a>, an iconic gull species that has declined in recent decades.</p>
<p>Elsewhere in the world, closures of other “forage fish” fisheries (those that catch species that are prey for larger predators) have revealed positive impacts. African penguins rear more chicks in years when anchovy and sardine fishery areas off the coastline of <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2017.2443">South Africa are closed</a>.</p>
<figure class="align-center ">
<img alt="Small thin silver fish dead laying on brown fishing net" src="https://images.theconversation.com/files/574503/original/file-20240208-18-xt7od3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574503/original/file-20240208-18-xt7od3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=481&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574503/original/file-20240208-18-xt7od3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=481&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574503/original/file-20240208-18-xt7od3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=481&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574503/original/file-20240208-18-xt7od3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=605&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574503/original/file-20240208-18-xt7od3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=605&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574503/original/file-20240208-18-xt7od3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=605&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sandeels are caught for use as food within the fish farming industry.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/small-sandeel-on-fish-net-1312001660">Coulanges/Shutterstock</a></span>
</figcaption>
</figure>
<p>As well as removing sandeels from the sea, industrial fishing can <a href="https://doi.org/10.1093/icesjms/fss155">disturb them</a> and drive them to different locations or to deeper depths, away from the hungry beaks of kittiwakes that catch prey for themselves and their chicks at the sea’s surface. </p>
<p>Relationships between the closure of sandeel area 4 and the breeding success of other sandeel-reliant seabirds around northern England and Scotland have not been obvious. This is potentially due to differences in foraging ranges and diving abilities between <a href="https://doi.org/10.1890/07-0797.1">different seabirds</a>. </p>
<p>For kittiwakes, breeding success initially rose after the closures until 2018, but did not bounce right back to the levels observed before <a href="https://doi.org/10.1016/j.biocon.2023.109990">fishing here began</a>, despite 20 years of potential recovery time. This suggests that other factors influence breeding success in kittiwake colonies. </p>
<h2>Climate drivers</h2>
<p>Studies of the impacts that <a href="https://doi.org/10.1016/j.fishres.2017.05.018">forage fishery closures</a> have on seabirds consistently flag the importance of environmental influences. Although fisheries could <a href="https://doi.org/10.1890/07-0797.1">exacerbate declines</a> in <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2017.2443">some seabird species</a>, changing environmental conditions have larger impacts. </p>
<p>Sandeels bury themselves in the sand during the winter and come out during the day to feed in the summer, but warmer temperatures can cause them to emerge from the sand <a href="https://doi.org/10.1002/ece3.8310">earlier in the year</a>. This change might have detrimental <a href="https://doi.org/10.3354/meps09520">knock-on effects</a> on the seabirds that feed sandeels to their chicks during their summer breeding seasons.</p>
<p>Climate change, which has already given rise to a <a href="https://www.mccip.org.uk/sites/default/files/2023-03/The%20Impacts%20of%20Climate%20Change%20on%20Sea%20Temperature%20around%20the%20UK%20and%20Ireland.pdf">warmer North Sea</a>, is a main driver of <a href="https://doi.org/10.1111/fog.12246">sandeel declines</a>. This has important ramifications for birds and other animals higher up the food chain. </p>
<p>The <a href="https://jncc.gov.uk/our-work/seabirds-count/">fourth national seabird census</a> (2015–2021) revealed that more than half the seabird species breeding around Britain and Ireland’s coastlines have declined over the past 20 years. Many of these declines have been linked to the influence of climate change on the availability of their prey. </p>
<p>The government’s environmental watchdog, the Office for Environmental Protection, recently warned that the government’s progress on its promise to stem declines in British nature by 2030 <a href="https://www.theoep.org.uk/report/government-remains-largely-track-meet-its-environmental-ambitions-finds-oep-annual-progress">has been scant</a>. The halting of sandeel fishing around Scotland and northern England is not enough to conserve the seabirds that breed around our coastlines. A more ambitious plan is called for.</p>
<p>Achieving the sandeel fisheries closure involved an immense lobbying effort that has been backed up by <a href="https://www.rspb.org.uk/whats-happening/news/sandeel-campaign-success-in-england">scientific evidence</a>. This success has demonstrated the importance that the British public places on protecting nature. Now, the government ought to not only combine fisheries closures with effective monitoring, but to diverge from burning fossil fuels that continue to heat our planet and choke conservation efforts. </p>
<p>Ultimately, to ensure that healthy sandeel populations will support seabirds in the future, we need to maintain cool seas that will allow their stocks to bounce back to pre-fishing levels.</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>Ruth Dunn has previously received funding from the Natural Environment Research Council (NERC).</span></em></p>Many seabird colonies around UK coastlines struggle to breed because the sandeels they feed on have been overfished. The upcoming closure of sandeel fisheries will be good news for marine wildlife.Ruth Dunn, Senior Research Associate in Marine Ecology, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2228342024-02-09T19:01:37Z2024-02-09T19:01:37ZAtlantic Ocean is headed for a tipping point − once melting glaciers shut down the Gulf Stream, we would see extreme climate change within decades, study shows<figure><img src="https://images.theconversation.com/files/573965/original/file-20240207-22-751n5r.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5607%2C3741&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Too much fresh water from Greenland's ice sheet can slow the Atlantic Ocean's circulation.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/iceberg-calving-from-eqip-glacier-on-disko-bay-royalty-free-image/534972902?phrase=melting+glaciers+greenland&adppopup=true">Paul Souders/Stone via Getty Images</a></span></figcaption></figure><p>Superstorms, abrupt climate shifts and New York City frozen in ice. That’s how the blockbuster Hollywood movie “<a href="https://www.imdb.com/title/tt0319262/">The Day After Tomorrow</a>” depicted an abrupt shutdown of the Atlantic Ocean’s circulation and the catastrophic consequences.</p>
<p>While Hollywood’s vision was over the top, the 2004 movie raised a serious question: If global warming shuts down the Atlantic Meridional Overturning Circulation, which is crucial for carrying heat from the tropics to the northern latitudes, how abrupt and severe would the climate changes be?</p>
<p>Twenty years after the movie’s release, we know a lot more about the Atlantic Ocean’s circulation. Instruments deployed in the ocean starting in 2004 <a href="http://dx.doi.org/10.1038/s41586-018-0006-5">show that the Atlantic Ocean circulation</a> has <a href="https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/">observably slowed</a> over the past two decades, possibly to its <a href="https://doi.org/10.1038/s41561-021-00699-z">weakest state in almost a millennium</a>. Studies also suggest that the circulation has reached a <a href="https://doi.org/10.1126/science.abn7950">dangerous tipping point</a> in <a href="https://doi.org/10.1126/science.aaf5529">the past</a> that sent it into a precipitous, unstoppable decline, and that it <a href="https://doi.org/10.1038/s41467-023-39810-w">could hit that tipping point again</a> as the planet warms and glaciers and ice sheets melt.</p>
<p>In a new study using the latest generation of Earth’s climate models, we simulated the flow of fresh water until the ocean circulation reached that tipping point. </p>
<p>The results showed that the circulation could <a href="http://www.science.org/doi/10.1126/sciadv.adk1189">fully shut down within a century</a> of hitting the tipping point, and that it’s headed in that direction. If that happened, average temperatures would drop by several degrees in North America, parts of Asia and Europe, and people would see severe and cascading consequences around the world.</p>
<p>We also discovered a physics-based early warning signal that can alert the world when the Atlantic Ocean circulation is nearing its tipping point.</p>
<h2>The ocean’s conveyor belt</h2>
<p>Ocean currents are driven by winds, tides and water <a href="https://doi.org/10.1007/s003820050144">density differences</a>.</p>
<p>In the Atlantic Ocean circulation, the relatively warm and salty surface water near the equator flows toward Greenland. During its journey it crosses the Caribbean Sea, loops up into the Gulf of Mexico, and then flows along the U.S. East Coast before crossing the Atlantic. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two illustrations show how the AMOC looks today and its weaker state in the future" src="https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573566/original/file-20240205-17-ttiy6v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How the Atlantic Ocean circulation changes as it slows.</span>
<span class="attribution"><a class="source" href="https://www.ipcc.ch/report/ar6/wg1/figures/chapter-9/faq-9-3-figure-1">IPCC 6th Assessment Report</a></span>
</figcaption>
</figure>
<p>This current, also known as the Gulf Stream, brings heat to Europe. As it flows northward and cools, the water mass becomes heavier. By the time it reaches Greenland, it starts to sink and flow southward. The sinking of water near Greenland pulls water from elsewhere in the Atlantic Ocean and the cycle repeats, like a <a href="https://doi.org/10.1002/2015RG000493">conveyor belt</a>.</p>
<p><a href="https://doi.org/10.1126/science.abn7950">Too much fresh water</a> from melting glaciers and the Greenland ice sheet can dilute the saltiness of the water, preventing it from sinking, and weaken this <a href="https://doi.org/10.1002/2015RG000493">ocean conveyor belt</a>. A <a href="https://doi.org/10.1073/pnas.97.4.1347">weaker conveyor belt</a> transports <a href="https://doi.org/10.1038/s41558-022-01380-y">less heat northward</a> and also enables less heavy water to reach Greenland, which <a href="https://doi.org/10.1073/pnas.97.4.1347">further weakens</a> the conveyor belt’s strength. Once it reaches the <a href="https://doi.org/10.1073/pnas.0705414105">tipping point</a>, it shuts down quickly.</p>
<h2>What happens to the climate at the tipping point?</h2>
<p>The existence of a tipping point was first noticed in an overly simplified model of the Atlantic Ocean circulation in the <a href="https://doi.org/10.1111/j.2153-3490.1961.tb00079.x">early 1960s</a>. Today’s more <a href="https://www.carbonbrief.org/cmip6-the-next-generation-of-climate-models-explained/">detailed climate models</a> indicate a continued <a href="https://doi.org/10.1029/2019GL086075">slowing of the conveyor belt’s strength</a> under climate change. However, an abrupt shutdown of the Atlantic Ocean circulation <a href="https://doi.org/10.1016/j.physd.2023.133984">appeared to be absent</a> in these climate models.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/p4pWafuvdrY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How the ocean conveyor belt works.</span></figcaption>
</figure>
<p>This is where our study comes in. We performed an experiment with a detailed climate model to find the tipping point for an abrupt shutdown by slowly increasing the input of fresh water. </p>
<p>We found that once it reaches the tipping point, the conveyor belt shuts down within 100 years. The heat transport toward the north is strongly reduced, leading to abrupt climate shifts.</p>
<h2>The result: Dangerous cold in the North</h2>
<p>Regions that are influenced by the Gulf Stream receive <a href="https://doi.org/10.1038/s41558-022-01380-y">substantially less heat</a> when the circulation stops. This cools the North American and European continents by a few degrees.</p>
<p>The European climate is much more influenced by the Gulf Stream than other regions. In our experiment, that meant parts of the continent changed at more than 5 degrees Fahrenheit (3 degrees Celsius) per decade – far faster than today’s global warming of about 0.36 F (0.2 C) per decade. We found that parts of Norway would experience temperature drops of more than 36 F (20 C). On the other hand, regions in the Southern Hemisphere would warm by a few degrees.</p>
<figure class="align-center ">
<img alt="Two maps show US and Europe both cooling by several degrees if the AMOC stops." src="https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=271&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=271&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=271&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=340&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=340&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573569/original/file-20240205-15-mqepgl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=340&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The annual mean temperature changes after the conveyor belt stops reflect an extreme temperature drop in northern Europe in particular.</span>
<span class="attribution"><a class="source" href="http://www.science.org/doi/10.1126/sciadv.adk1189">René M. van Westen</a></span>
</figcaption>
</figure>
<p>These temperature changes develop over about 100 years. That might seem like a long time, but on typical climate time scales, it is abrupt.</p>
<p>The conveyor belt shutting down would also affect sea level and precipitation patterns, which can <a href="https://doi.org/10.1088/1748-9326/ac3955">push other ecosystems closer to their tipping points</a>. For example, the Amazon rainforest is vulnerable to <a href="https://doi.org/10.1073/pnas.2120777119">declining precipitation</a>. If its forest ecosystem turned to grassland, the transition would <a href="https://esd.copernicus.org/articles/13/1667/2022/">release carbon</a> to the atmosphere and result in the loss of a valuable carbon sink, further accelerating climate change.</p>
<p>The Atlantic circulation has <a href="https://doi.org/10.1126/science.aaf5529">slowed significantly in the distant past</a>. During <a href="https://doi.org/10.1146/annurev-marine-010816-060415">glacial periods</a> when ice sheets that covered large parts of the planet were melting, the influx of fresh water slowed the Atlantic circulation, triggering huge climate fluctuations.</p>
<h2>So, when will we see this tipping point?</h2>
<p>The big question – when will the Atlantic circulation reach a tipping point – remains unanswered. Observations don’t go back far enough to provide a clear result. While a recent study suggested that the conveyor belt is rapidly <a href="https://doi.org/10.1038/s41467-023-39810-w">approaching its tipping point</a>, possibly within a few years, these statistical analyses made several assumptions that give rise to uncertainty.</p>
<p>Instead, we were able to develop a physics-based and observable early warning signal involving the salinity transport at the southern boundary of the Atlantic Ocean. Once a threshold is reached, the tipping point is likely to follow in one to four decades.</p>
<figure class="align-center ">
<img alt="A line chart of circulation strength shows a quick drop-off after the amount of freshwater in the ocean hits a tipping point." src="https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=467&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=467&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=467&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=586&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=586&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574182/original/file-20240207-28-udb2b3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=586&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A climate model experiment shows how quickly the AMOC slows once it reaches a tipping point with a threshold of fresh water entering the ocean. How soon that will happen remains an open question.</span>
<span class="attribution"><a class="source" href="http://www.science.org/doi/10.1126/sciadv.adk1189">René M. van Westen</a></span>
</figcaption>
</figure>
<p>The climate impacts from our study underline the severity of such an abrupt conveyor belt collapse. The temperature, sea level and precipitation changes will severely affect society, and the <a href="https://doi.org/10.1029/2023GL106088">climate shifts are unstoppable</a> on human time scales.</p>
<p>It might seem counterintuitive to worry about extreme cold as the planet warms, but if the main Atlantic Ocean circulation shuts down from too much meltwater pouring in, that’s the risk ahead.</p>
<p><em>This article was updated on Feb. 11, 2024, to fix a typo: The experiment found temperatures in parts of Europe changed by more than 5 F per decade.</em></p><img src="https://counter.theconversation.com/content/222834/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>René van Westen receives funding from the European Research Council (ERC-AdG project 101055096, TAOC).</span></em></p><p class="fine-print"><em><span>Henk A. Dijkstra receives funding from the European Research Council (ERC-AdG project 101055096, TAOC, PI: Dijkstra). </span></em></p><p class="fine-print"><em><span>Michael Kliphuis 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>Scientists now have a better understanding of the risks ahead and a new early warning signal to watch for.René van Westen, Postdoctoral Researcher in Climate Physics, Utrecht UniversityHenk A. Dijkstra, Professor of Physics, Utrecht UniversityMichael Kliphuis, Climate Model Specialist, Utrecht UniversityLicensed 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>
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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>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/2220912024-02-01T14:50:17Z2024-02-01T14:50:17ZHermit crabs find new homes in plastic waste: shell shortage or clever choice?<figure><img src="https://images.theconversation.com/files/571882/original/file-20240129-15-j4gupx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists have found that hermit crabs are increasingly using plastic and other litter as makeshift shell homes</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hermit-crab-carrying-plastic-bottle-cap-1962035515">metamorworks/Shutterstock</a></span></figcaption></figure><p>Land hermit crabs have been using bottle tops, parts of old light bulbs and broken glass bottles, instead of shells. </p>
<p>New research by <a href="https://www.sciencedirect.com/science/article/pii/S0048969723075885">Polish researchers</a> studied 386 images of hermit crabs occupying these artificial shells. The photos had been uploaded by users to online platforms, then analysed by scientists using a research approach known as <a href="https://www.sciencedirect.com/science/article/pii/S016953472030077X">iEcology</a>. Of the 386 photos, the vast majority, 326 cases, featured hermit crabs using plastic items as shelters. </p>
<p>At first glance, this is a striking example of how human activities can alter the behaviour of wild animals, and potentially the ways that <a href="https://www.frontiersin.org/articles/10.3389/fevo.2022.893453/full">populations and ecosystems function</a> as a result. But there are lots of factors at play and, while it’s easy to jump to conclusions, it’s important to consider exactly what might be driving this particular change. </p>
<h2>Shell selection</h2>
<p>Hermit crabs are an excellent model organism to study because they behave in many different ways and those differences can be easily measured. Instead of continuously growing their own shell to protect their body, like a normal crab or a lobster would, they use empty shells left behind by dead snails. As they walk around, the shell protects their soft abdomen but whenever they are threatened they retract their whole body into the shell. Their shells act as portable shelters.</p>
<p>Having a good enough shell is critical to an individual’s survival so they acquire and upgrade their shells as they grow. They fight other hermit crabs for shells and assess any new shells that they might find for suitability. Primarily, they look for shells that are large enough to protect them, but <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2010.0761">their decision-making</a> also takes into account the type of snail shell, its condition and even its colour – a factor that could impact how conspicuous the crab might be.</p>
<p>Another factor that constrains shell choice is the actual availability of suitable shells. For some as yet unknown reason, a proportion of land hermit crabs are choosing to occupy plastic items rather than natural shells, as highlighted by this <a href="https://www.sciencedirect.com/science/article/pii/S0048969723075885">latest study</a>. </p>
<h2>Housing crisis or ingenious new move?</h2>
<p>Humans have intentionally changed the behaviour of animals for millennia, through the process of <a href="https://www.sciencedirect.com/science/article/abs/pii/S2213305413000052">domestication</a>. Any unintended behavioural changes in natural animal populations are potentially concerning, but how worried should we be about hermit crabs using plastic litter as shelter? </p>
<p>The Polish research raises a number of questions. First, how prevalent is the adoption of plastic litter instead of shells? While 326 crabs using plastic seems like a lot, this is likely to be an underestimation of the raw number given that users are likely to encounter crabs only in accessible parts of the populations. Conversely, it seems probable that users could be biased towards uploading striking or unusual images, so the iEcology approach might produce an exaggerated impression of the proportion of individuals in a population opting for plastic over natural shells. We need structured field surveys to clarify this. </p>
<p>Second, why are some individual crabs using plastic? One possibility is that they are forced to due to a lack of natural shells, but we can’t test this hypothesis without more information on the demographics of local snail populations. Or perhaps the crabs prefer plastic or find it easier to locate, compared with real shells? As the authors point out, plastic might be lighter than the equivalent shells affording the same amount of protection but at lower energy cost of carrying them. Intriguingly, chemicals that leach out of plastic are known to attract marine hermit crabs by <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X21005671#:%7E:text=Our%20findings%20show%20that%20the,the%20artificial%20feeding%20stimulant%20betaine">mimicking the odour of food</a>. </p>
<figure class="align-center ">
<img alt="Hermit crab using red plastic bottle cap as a shell, walking across beach surface covered in sand and seaweed." src="https://images.theconversation.com/files/572811/original/file-20240201-23-4epat6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572811/original/file-20240201-23-4epat6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572811/original/file-20240201-23-4epat6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572811/original/file-20240201-23-4epat6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572811/original/file-20240201-23-4epat6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572811/original/file-20240201-23-4epat6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572811/original/file-20240201-23-4epat6.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">As hermit crabs adapt to an increase in plastic pollution, more research is needed to investigate the nuances.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hermit-crab-plastic-shell-zanzibar-2270754839">Bertrand Godfroid/Shutterstock</a></span>
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<p>This leads to a third question about the possible downsides of using plastic. Compared to real shells plastic waste tends to be brighter and might contrast more with the background making the crabs more vulnerable to predators. Additionally, we know that exposure to microplastics and compounds that leach from plastic can change the behaviour of hermit crabs, making them <a href="https://pubmed.ncbi.nlm.nih.gov/36978596/#:%7E:text=Plastic%2Dexposed%20hermit%20crabs%20were,exposure%20disrupting%20hermit%20crab%20cognition">less fussy</a> about the shells that they choose, less adept at <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8511743/">fighting for shells</a> and even changing their personalities by making them more prone to <a href="https://www.sciencedirect.com/science/article/pii/S2666911020300058">take risks</a>. To answer these questions about the causes and consequences of hermit crabs using plastic waste in this way, we need to investigate their shell selection behaviour through a series of laboratory experiments.</p>
<h2>Pollution changes behaviour</h2>
<p>Plastic pollution is just one of the ways we are changing our environment. It’s by far the most <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X14008571">highly reported form</a> of debris that we have introduced to marine environments. But animal behaviour is affected by <a href="https://www.sciencedirect.com/science/article/pii/S0048969723059879?via%3Dihub">other forms of pollution</a> too, including microplastics, pharmaceuticals, light and noise, plus the rising temperatures and ocean acidification caused by climate change. </p>
<p>So while investigating the use of plastic waste by hermit crabs could help us better understand the consequences of certain human impacts on the environment, it doesn’t show how exactly animals will adjust to the Anthropocene, the era during which human activity has been having a significant impact on the planet. Will they cope by using plastic behavioural responses or evolve across generations, or perhaps both? In my view, the iEcology approach cannot answer questions like this. Rather, this study acts as an alarm bell highlighting potential changes that now need to be fully investigated.</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>Mark Briffa works for the University of Plymouth. He receives funding from the UK BBSRC. </span></em></p>Hermit crabs have been using plastic waste such as bottle tops as homes instead of empty snail shells.Mark Briffa, Professor of Animal Behaviour, University of PlymouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2209092024-01-31T23:08:48Z2024-01-31T23:08:48ZMining the depths: Norway’s deep-sea exploitation could put it in environmental and legal murky waters<figure><img src="https://images.theconversation.com/files/572593/original/file-20240131-19-meg6yo.jpeg?ixlib=rb-1.1.0&rect=0%2C2%2C1920%2C1276&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Icebergs floating in the ocean near Svalbard, an Arctic island chain on the edge of Norway’s proposed exploitation zone.</span> <span class="attribution"><span class="source">(Christopher Michel/Flickr)</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/mining-the-depths-norways-deep-sea-exploitation-could-put-it-in-environmental-and-legal-murky-waters" width="100%" height="400"></iframe>
<p>Norway has a reputation for environmental leadership, from championing <a href="https://www.cbd.int/countries/profile/?country=no">international biodiversity policies</a> to its wilderness <a href="https://www.regjeringen.no/en/dokumenter/outdoor-recreation-act/id172932/">protection</a> and ambitious <a href="https://www.regjeringen.no/en/dokumenter/nature-diversity-act/id570549/">biodiversity</a> regulations.</p>
<p>Now it is leading into another area, leveraging its long legacy of offshore oil and gas production into developing deep-sea mining.</p>
<p>In January Norway became the first nation to open its continental shelf to commercial deep-sea mineral exploration. The <a href="https://www.regjeringen.no/en/aktuelt/norway-gives-green-light-for-seabed-minerals/id3021433/">approved proposal opens the door for “sustainable and responsible” exploration within an area of 281,000 square kilometres, roughly the size of Italy</a>.</p>
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Read more:
<a href="https://theconversation.com/deep-sea-mining-may-wipe-out-species-we-have-only-just-discovered-173558">Deep-sea mining may wipe out species we have only just discovered</a>
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<p>But determining what constitutes sustainable and responsible deep-sea mining could put Norway in murky legal waters by pushing the boundaries of several international agreements to which it is a signatory. Beyond legal action, Norwegian society, businesses and global politics will play a part in deciding how this controversial industry develops. Other countries, such as Canada, should take note.</p>
<p>While the current government of Canada opposes deep-sea mining and has issued a <a href="https://thenarwhal.ca/deep-sea-mining-canada-moratorium/">domestic moratorium</a>, there are <a href="https://www.bbc.com/news/business-67935057">Canadian companies lobbying</a> for this industry to open in international waters. But there are more than a few hurdles in the way of a booming deep-sea mining industry — and for good reason.</p>
<h2>Mining in the deep</h2>
<p>The <a href="https://www.sodir.no/en/whats-new/news/general-news/2024/norwegian-shelf-opened-for-mineral-activity/">proposal to authorize deep-sea mining</a> was initiated by the ministry that has overseen Norway’s huge offshore oil industry for decades. It was asked to map “commercially interesting mineral deposits on the Norwegian continental shelf” and found <a href="https://www.sodir.no/en/facts/seabed-minerals/">sulphides and manganese crusts</a> with high concentrations of copper, zinc and cobalt, as well as rare earth elements.</p>
<p>The technologies needed to mine manganese crusts differ than those needed to mine sulphides. Manganese crusts are mined by scraping thin layers of minerals off of the edges of the deep-sea rocks, said Walter Sognnes, CEO of deep-sea mining company Loke Marine Minerals based in Norway, whom I interviewed for this story. Whereas, <a href="https://www.sciencenorway.no/deep-sea-mineralogy-mining/heres-how-valuable-resources-can-be-extracted-from-the-seabed-theres-a-goldmine-out-there/2285672">sulphides are mined by drilling into the seabed using technology from the oil and gas industry</a>.</p>
<p>Norway’s Ministry of Energy believes that the minerals from deep-sea mining could both meet the demand required of the green energy transition and secure the supply. But opposing scientists and organizations <a href="https://ejfoundation.org/reports/critical-minerals-and-the-green-transition-do-we-need-to-mine-the-deep-seas">argue that this logic is flawed</a>.</p>
<p>Opponents of deep-sea mining say that it will <a href="https://doi.org/10.1038/d41586-024-00088-7">irreversibly damage biodiversity and ecosystems</a>, and warn that it will <a href="https://thefishingdaily.com/latest-news/norwegian-fishing-slams-government-proposal-on-deep-sea-mining/">impact fisheries</a>, <a href="https://doi.org/10.1002/ieam.4071">cause sediment plumes, damage the seabed, increase pollution and contribute to several other spillover effects</a>.</p>
<p>If the Norwegian government advances deep-sea mining beyond the exploration phase, Sognnes expects that full-scale mining operations could be underway in Norway by the early 2030s.</p>
<h2>Norway’s continental shelf</h2>
<p>Under United Nations law, coastal countries have a <a href="https://oceanservice.noaa.gov/facts/eez.html">200 nautical mile Exclusive Economic Zone</a> extending out from their coastlines within which they have the right to explore and use the resources on the seabed and <a href="https://www.geo-ocean.fr/en/Science-for-all/Our-classrooms/Hydrothermal-systems/The-water-column">water column</a>.</p>
<p>This is true for Norway, however, in 2009 Norway’s request to extend its continental shelf was approved by a <a href="https://www.un.org/depts/los/clcs_new/submissions_files/submission_nor.htm">governing body at the UN</a>. This decision further added 235,000 square kilometres of seabed to Norway’s territory — though the water above the seabed is, crucially, not included as Norwegian territory.</p>
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<figcaption><span class="caption">A report on deep-sea mining produced by DW Planet A.</span></figcaption>
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<p>That means that Norway’s proposed deep-sea mining activities will take place on the seabed, under Norway’s jurisdiction. However, as professor of maritime law at the University of Oslo Alla Pozdnakova described to me, any mining activities on Norway’s patch of sea-bed will “inevitably affect the water column where the <a href="https://news.un.org/en/story/2023/03/1134157">(High Seas) Treaty</a> will eventually apply” — with potentially significant legal repercussions.</p>
<h2>The High Seas — or not?</h2>
<p>In 2023, the UN’s High Seas Treaty was adopted by more than 80 nations — including <a href="https://www.regjeringen.no/en/aktuelt/worlds-countries-reach-agreement-on-conservation-of-marine-biodiversity-in-the-high-seas/id2965405/">Norway</a> — and is meant to manage the two-thirds of the oceans outside any one country’s responsibility.</p>
<p>Mining brings many complicated legal issues that could involve the High Seas Treaty, said Pozdnakova.</p>
<p>For example, any of the 80 countries that signed the High Seas Treaty could propose a marine protected area anywhere in the high seas. In theory, this could be an area that Norway plans to deep-sea mine.</p>
<p>It’s also important to note that while the High Seas Treaty has been signed by Norway, it has not yet come into effect. But the timing of the treaty being ratified by Norway could align with deep-sea mining operations entering an exploitation phase, said Pozdnakova, which could further complicate the legal and political landscape for Norway.</p>
<p>There are also regional agreements that could raise concerns.</p>
<p>The <a href="https://www.jus.uio.no/english/services/library/treaties/01/1-11/svalbard-treaty.html">Svalbard Treaty</a>, for example, is an agreement signed by Canada and 45 other countries. The treaty gives Norway sovereign rights over the archipelago. And it calls for equality between the signatories when it comes to maritime, industrial, mining and commercial activities.</p>
<p>Pozdnakova notes that there is some debate about the geographic extent of the treaty, which was signed in 1920. But depending on the treaty’s extent, some of the proposed area could overlap.</p>
<p>“Once some companies get a license…then immediately you have this issue going on about whether the Svalbard Treaty applies to this particular area and what it means,” said Pozdnakova.</p>
<p>The convention that protects the marine environment of the North-East Atlantic Ocean, known as the <a href="https://www.ospar.org/convention">OSPAR Convention</a>, could also raise concerns about deep-sea mining’s impact in the region from sediment plumes to impacts on fisheries and others. However, the convention does not prohibit Norway’s activities on its continental shelf, said Pozdnakova.</p>
<h2>Beyond the laws</h2>
<p><a href="https://savethehighseas.org/voices-calling-for-a-moratorium-governments-and-parliamentarians/">Several countries</a>, including Canada, France and others, have called for a moratorium or precautionary pause on deep-sea mining in “<a href="https://www.canada.ca/en/global-affairs/news/2023/07/canadas-position-on-seabed-mining-in-areas-beyond-national-jurisdiction.html">areas beyond national jurisdiction</a>.”</p>
<p>Norway opening its continental shelf throws a wrench in the moratorium movement, said Rak Kim, associate professor of earth system governance at the Copernicus Institute of Sustainable Development, Utrecht University.</p>
<p>“I think that’s why it is such a disappointment that Norway has taken a different stance. Not because of the immediate impact that exploration might have, but it changes the political dynamic,” he said.</p>
<p>However, legal action is not the only way Norway could run into trouble in getting its deep-sea mining industry up and running.</p>
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Read more:
<a href="https://theconversation.com/mining-the-seabed-for-clean-tech-minerals-could-destroy-ecosystems-will-it-get-the-green-light-209690">Mining the seabed for clean-tech minerals could destroy ecosystems. Will it get the green light?</a>
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<p>Sustainable financing could play a role — especially if there is societal push back. “We already see some examples of some banks, financial institutions not wanting to invest in these kinds of activities,” said Pozdnakova. “The implications may be quite serious through these indirect kinds of actions.”</p>
<p>If society wants to keep its status quo, making more electric cars, mobile phones and computers, there is probably a reasonable argument to make for deep-sea mining, said Kim. But “the more fundamental question is, is technology the answer to the sustainability problems that we are facing?”</p>
<p>If technology is not the answer, “then maybe society needs to make a fundamental transition to something else,” said Kim.</p><img src="https://counter.theconversation.com/content/220909/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ashley Perl works as a communications specialist for the World Wide Fund for Nature. This article was produced independently of her work there but as part of her work as a fellow in the Dalla Lana Fellowship in Journalism and Health Impact at the University of Toronto.</span></em></p>Norway has become the first nation on earth to allow deep-sea mineral exploration. But opening this industry could put Norway in murky legal waters.Ashley Perl, Fellow, Dalla Lana Fellowship in Journalism and Health Impact, University of TorontoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2206292024-01-31T13:36:25Z2024-01-31T13:36:25Z‘Jaws’ portrayed sharks as monsters 50 years ago, but it also inspired a generation of shark scientists<figure><img src="https://images.theconversation.com/files/572002/original/file-20240129-17-8m3oe7.jpg?ixlib=rb-1.1.0&rect=37%2C0%2C4952%2C3261&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A paleontologist wears a T-shirt showing _Strophodus rebecae_, a shark species with flat teeth that lived millions of years ago.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/palaeontologist-edwin-cadena-shows-a-t-shirt-with-an-image-news-photo/1241210531">Juan Pablo Pino/AFP via Getty Images</a></span></figcaption></figure><p>Human fear of sharks has deep roots. Written works and art from the ancient world contain references to <a href="https://www.artmajeur.com/en/magazine/5-art-history/sharks-in-art/331942">sharks preying on sailors</a> as early as the eighth century B.C.E. </p>
<p>Relayed back to land, stories about shark encounters have been <a href="https://etc.usf.edu/lit2go/42/moby-dick/747/chapter-66-the-shark-massacre/">embellished and amplified</a>. Together with the fact that from time to time – very rarely – sharks bite humans, people have been primed for centuries to imagine terrifying situations at sea.</p>
<p>In 1974, Peter Benchley’s <a href="https://www.penguinrandomhouse.ca/books/11203/jaws-by-peter-benchley/9780345544148/excerpt">bestselling novel “Jaws</a>” fanned this fear into a wildfire that spread around the world. The book sold more than 5 million copies in the U.S. within a year and was quickly followed by <a href="https://www.imdb.com/title/tt0073195/">Steven Spielberg’s 1975 movie</a>, which became the highest-grossing film in history at that time. Virtually all audiences embraced the idea, depicted vividly in the movie and its sequels, that sharks were malevolent, vindictive creatures that prowled coastal waters seeking to feed on unsuspecting bathers. </p>
<p>But “Jaws” also spawned widespread interest in better understanding sharks. </p>
<p>Previously, shark research had largely been the esoteric domain of a handful of academic specialists. Thanks to interest sparked by “Jaws,” we now know that there are many more kinds of sharks than scientists were aware of in 1974, and that sharks do more interesting things than researchers ever anticipated. Benchley himself became an avid <a href="https://www.latimes.com/archives/la-xpm-2006-feb-13-me-benchley13-story.html">spokesman for shark protection and marine conservation</a>.</p>
<p>In my own 30-year career studying <a href="https://scholar.google.com/citations?user=FKrC4FYAAAAJ&hl=en">sharks and their close relatives, skates and rays</a>, I’ve seen attitudes evolve and interest in understanding sharks expand enormously. Here’s how things have changed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.jpg?ixlib=rb-1.1.0&rect=32%2C8%2C5434%2C3630&q=45&auto=format&w=1000&fit=clip"><img alt="A man stands on the prow of a boat, extending a pole into the water toward a large dark shape." src="https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.jpg?ixlib=rb-1.1.0&rect=32%2C8%2C5434%2C3630&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572000/original/file-20240129-27-l4g7ei.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">Marine biologist Greg Skomal of the Massachusetts Division of Marine Fisheries captures video footage of a white shark off Cape Cod, Oct. 21, 2022.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/dr-greg-skomal-shark-researcher-for-massachusetts-marine-news-photo/1244267691">Joseph Prezioso/AFP via Getty Images</a></span>
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<h2>Swimming into the spotlight</h2>
<p>Before the mid-1970s, much of what was known about sharks came via people who went to sea. In 1958, the U.S. Navy established the <a href="https://www.floridamuseum.ufl.edu/shark-attacks/">International Shark Attack File</a> – the world’s only scientifically documented, comprehensive database of all known shark attacks – to reduce wartime risks to sailors stranded at sea when their ships sank. </p>
<p>Today the file is managed by the <a href="https://www.floridamuseum.ufl.edu/">Florida Museum of Natural History</a> and the <a href="https://elasmo.org/">American Elasmobranch Society</a>, a professional organization for shark researchers. It works to inform the public about shark-human interactions and ways to reduce the risk of shark bites.</p>
<p>In 1962, <a href="https://www.fisheries.noaa.gov/feature-story/john-jack-casey-internationally-recognized-shark-researcher-mentor-and-narragansett">Jack Casey</a>, a pioneer of modern shark research, initiated the <a href="https://www.fisheries.noaa.gov/resource/document/cooperative-shark-tagging-program">Cooperative Shark Tagging Program</a>. This initiative, which is still running today, relied on Atlantic commercial fishermen to report and return tags they found on sharks, so that government scientists could calculate how far the sharks had moved after being tagged. </p>
<p>After “Jaws,” shark research quickly went mainstream. The American Elasmobranch Society was founded in 1982. Graduate students lined up to study shark behavior, and the number of published shark studies <a href="https://thefisheriesblog.com/2015/06/15/thank-you-jaws-the-upside-for-sharks-40-years-later/">sharply increased</a>.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/reel/Cz6muU6u3Mn/?utm_source=ig_web_copy_link\u0026igsh=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Field research on sharks expanded in parallel with growing interest in extreme outdoor sports like surfing, parasailing and scuba diving. Electronic tags enabled researchers to monitor sharks’ movements in real time. DNA sequencing technologies provided cost-effective ways to determine how different species were related to one another, what they were eating and how populations were structured.</p>
<p>This interest also had a sensational side, embodied in the Discovery Channel’s launch in 1988 of <a href="https://www.discovery.com/shark-week">Shark Week</a>. This annual block of programming, ostensibly designed to educate the public about shark biology and counter negative publicity about sharks, was a commercial venture that exploited the tension between people’s deep-seated fear of sharks and their yearning to understand what made these animals tick. </p>
<p>Shark Week featured made-for-TV stories that focused on <a href="https://www.washingtonpost.com/news/arts-and-entertainment/wp/2018/07/26/a-fake-shark-week-documentary-about-megalodons-caused-controversy-why-is-discovery-bringing-it-up-again/">fictional scientific research projects</a>. It was wildly successful and remains so today, in spite of critiques from some researchers who call it <a href="https://theconversation.com/beware-of-shark-week-scientists-watched-202-episodes-and-found-them-filled-with-junk-science-misinformation-and-white-male-experts-named-mike-195180">a major source of misinformation</a> about sharks and shark science.</p>
<h2>Physical, social and genetic insights</h2>
<p>Contrary to the long-held notion that sharks are mindless killers, they exhibit a wide range of traits and behavior. For example, the velvet belly lantern shark communicates through flashes of light from <a href="https://doi.org/10.4161/cib.4.3.14888">organs on the sides of its body</a>. Female hammerhead sharks can <a href="http://dx.doi.org/10.1098/rsbl.2007.0189">clone perfect replicas of themselves</a> without male sperm. </p>
<p>Sharks have the most sensitive electrical detectors thus far discovered in the natural world – networks of pores and nerves in their heads, known as <a href="https://www.scienceandthesea.org/program/201105/ampullae-lorenzini">ampullae of Lorenzini</a>, after Italian scientist Stefano Lorenzini, who first described these features in the 17th century. Sharks use these networks to navigate in the open ocean, <a href="https://doi.org/10.1016/j.cub.2021.03.103">using Earth’s magnetic field for orientation</a>. </p>
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<a href="https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three snorkelers swim above a large spotted shark." src="https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572016/original/file-20240129-17-i6lyza.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">Snorkelers swim above a whale shark near the Maldives in the Indian Ocean. The largest fish in the sea, whale sharks are filter feeders that prey on plankton.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/gTntz7">Tchami/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Another intriguing discovery is that some shark species, including makos and blue sharks, <a href="http://dx.doi.org/10.1098/rsbl.2008.0761">segregate by both sex and size</a>. Among these species, cohorts of males and females of different sizes are often found in distinct groups. This finding suggests that some sharks may have <a href="https://www.britannica.com/topic/hierarchy-social-science">social hierarchies</a>, like those seen in some primates and hoofed mammals. </p>
<p>Genetic studies have helped researchers explore questions such as why some sharks <a href="https://theconversation.com/why-do-hammerhead-sharks-have-hammer-shaped-heads-184372">have heads shaped like hammers or shovels</a>. They also show that sharks have the <a href="https://doi.org/10.1038/s41467-023-42238-x">lowest mutation rate of any vertebrate animal</a>. This is notable because mutations are the raw material for evolution: The higher the mutation rate, the better a species can adapt to environmental change. </p>
<p>However, sharks have been around for 400 million years and have been through some of the most extreme environmental changes on earth. It’s not known yet how they have persisted so successfully with such a low mutation rate.</p>
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<figcaption><span class="caption">Gavin Naylor, director of the Florida Program for Shark Research, describes how DNA analysis provides insights into shark science.</span></figcaption>
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<h2>The marquee species</h2>
<p>White sharks, the focal species of “Jaws,” attract enormous public interest, although much about them is still unknown. They can live to age 70, and they routinely swim thousands of miles every year. Those in the Western North Atlantic tend to move north-south between Canada and the Gulf of Mexico; white sharks on the U.S. west coast move east-west between California and the Central Pacific. </p>
<p>We now know that juvenile white sharks feed almost exclusively on fishes and stingrays, and don’t start incorporating seals and other marine mammals into their diets until they are the equivalent of teenagers and have grown to about 12 feet long. Most confirmed white shark bites on humans seem to be by animals that are between 12 and 15 feet long. This supports the theory that almost all bites by white sharks on humans are <a href="https://doi.org/10.1098/rsif.2021.0533">cases of mistaken identity</a>, where humans resemble the seals that sharks prey on.</p>
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<h2>Still in the water</h2>
<p>Although “Jaws” had a <a href="https://www.today.com/popculture/jaws-took-chomp-out-pop-culture-40-years-ago-1d79919594">widespread cultural impact</a>, it didn’t keep surfers and bathers from enjoying the ocean. </p>
<p>Data from the International Shark Attack File on confirmed unprovoked bites by white sharks from the 1960s to the present day shows a continuous increase, although the number of incidents yearly is quite low. This pattern is consistent with growing numbers of people <a href="https://coast.noaa.gov/states/fast-facts/tourism-and-recreation.html">pursuing recreational activities at the coasts</a>. </p>
<p>Around the world, there have been 363 <a href="https://www.floridamuseum.ufl.edu/shark-attacks/maps/world-interactive/">confirmed, unprovoked bites by white sharks</a> since 1960. Of these, 73 were fatal. The World Health Organization estimates that there are <a href="https://www.who.int/news-room/fact-sheets/detail/drowning">236,000 deaths yearly due to drowning</a>, which translates to around 15 million drowning deaths over the same time period. </p>
<p>In other words, people are roughly 200,000 times more likely to drown than to die from a white shark bite. Indeed, surfers are more likely to die in a car crash on the way to the beach than they are to be bitten by a shark.</p><img src="https://counter.theconversation.com/content/220629/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gavin Naylor receives funding from the National Science Foundation and the Lenfest Foundation.</span></em></p>‘Jaws,’ published in 1974, terrified the public of sharks, but it also brought shark research into the scientific mainstream.Gavin Naylor, Director of Florida Program for Shark Research, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2219662024-01-29T00:20:35Z2024-01-29T00:20:35ZSediment runoff from the land is killing NZ’s seas – it’s time to take action<p>The fishers at Separation Point, between Golden Bay and Tasman Bay in New Zealand’s northwest South Island, used to be cautious. Something they called “hard coral” would tear their nets. If you dived down about 30 metres, you could see why: extensive reefs.</p>
<p>These reefs were constructed by <a href="https://www.sciencelearn.org.nz/resources/147-bryozoans">bryozoans</a>, tiny polyp-like creatures that cooperate to build large, branching colonies. They are similar to corals but live in deeper and cooler water.</p>
<p>The reefs at Separation Point were gorgeous and biodiverse. They provided shelter for small animals such as oysters and young fish. In 1980, the world’s first bryozoan-based fishing exclusion area was created to protect them: 146 square kilometres of seafloor was closed to most fishing, from the coastline to a depth of about 50 metres.</p>
<p>It went well at first. A 1983 study from the National Institute of Water and Atmospheric Research (<a href="https://niwa.co.nz/">NIWA</a>) of just one reef found 37 species of bryozoans and another 39 invertebrate species, plus numerous fish. In 2008, a <a href="https://niwa.co.nz/publications/water-and-atmosphere/vol16-no3-september-2008/effects-of-a-30-year-fishing-ban">study comparing fished and unfished areas</a> off Separation Point found more biodiversity where fishing had been limited.</p>
<p>Alas, subsequent developments have not been so kind. Land clearance for agriculture and forestry since human occupation has resulted in a ten-fold increase in sediment runoff in the area. </p>
<p>Thick beds of mud and silt have built up, destroying and burying the reefs. A <a href="https://www.stuff.co.nz/environment/128742534/protected-fish-nursery-wiped-out-by-mud">survey of the same area</a> in 2021 found flat mud deposits, with the occasional small, dead bryozoan sticking up. No fish remained in this marine ghost town.</p>
<h2>Part of a bigger picture</h2>
<p>These days it’s hard to escape news that the ocean is in trouble. Warming waters cause heatwaves that bleach corals. Fish and sharks appear where they never used to. Plastic is everywhere, including the stomachs of dolphins and penguins. Overfishing is causing populations to crash.</p>
<p>Meanwhile, sea levels are rising, dredging and mining are destroying ecosystems, while underwater engine noise and artificial light are changing how animals behave. Even the fundamental chemistry of seawater is changing as CO₂ dissolves in it. UNESCO’s <a href="https://oceanliteracy.unesco.org/?post-types=all&sort=popular">Ocean Literacy Portal</a> reads like an obituary.</p>
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Read more:
<a href="https://theconversation.com/plastic-pollution-in-some-nz-lakes-is-comparable-to-northern-hemisphere-lakes-in-highly-populated-areas-global-study-finds-209509">Plastic pollution in some NZ lakes is comparable to northern hemisphere lakes in highly populated areas, global study finds</a>
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<p>But there’s another problem often left off that grim list: sediment runoff. When people remove trees, build roads and overstock paddocks, sand, mud and silt flow into the sea.</p>
<p>The resulting damage to coastal ecosystems gets little press, despite being described by the US National Oceanic and Atmospheric Administration as the <a href="https://oceanservice.noaa.gov/facts/pollution.html">greatest single source of pollution</a> in the world’s waterways and coasts. </p>
<p>The first objective of the <a href="https://www.doc.govt.nz/about-us/science-publications/conservation-publications/marine-and-coastal/new-zealand-coastal-policy-statement/new-zealand-coastal-policy-statement-2010/">New Zealand Coastal Policy Statement</a> in 2010 was to maintain and restore marine water quality. But that’s far from what we have today.</p>
<p>Dark waters, turbid with silt, affect marine life. We are increasingly aware of the changes in seaweed cover around New Zealand, from damage to kelp canopies to changes in phytoplankton. Seaweeds need light and clear waters.</p>
<p>Bryozoans, barnacles, oysters, cockles and scallops are suffering too. They literally starve to death by collecting dirt particles rather than food. Their delicate feeding tentacles are damaged or clogged, while their neighbours (such as pāua) are smothered or buried.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/nzs-vital-kelp-forests-are-in-peril-from-ocean-warming-threatening-the-important-species-that-rely-on-them-212956">NZ’s vital kelp forests are in peril from ocean warming – threatening the important species that rely on them</a>
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</em>
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<h2>New Zealand’s disproportionate problem</h2>
<p>Sediment runoff is most likely in wet places with high and regular rainfall, prone to being disturbed by storms and earthquakes, and with steep slopes, young rocks and soils. Agricultural land is a particularly strong source of sediment to waterways. Sound like somewhere you know?</p>
<p>Aotearoa New Zealand is eroding into the sea right under our feet. Over 200 million tonnes of sediment are <a href="https://niwa.co.nz/news/reducing-sedimentation">transported by rivers to the sea</a> each year, making fine sediment the most important and widespread water contaminant in this country.</p>
<p>Despite covering only 0.2% of global land area, the Ministry for the Environment <a href="https://environment.govt.nz/publications/new-zealands-land-at-a-glance-our-land-2018/">reported in 2018</a> that New Zealand contributes 1.7% of the sediment to the world’s oceans.</p>
<p>Removal of forest and well-rooted plants, overgrazing and construction all result in sediment washing into the sea. Excavating old soils containing now-outlawed pollutants such as DDT, tin or lead exacerbates the problem.</p>
<p>Under the Resource Management Act, regional councils have the authority to prevent discharge of contaminants into water, and the responsibility to manage catchments to minimise sediment getting to the sea. Murky coastal waters suggest they’re not coping with this task. </p>
<h2>Action and policy needed</h2>
<p>We can make a difference. Planting and avoiding runoff are the most obvious solutions. Roots hold soil better than anything humans have invented. Usefully, they also direct water deep into the ground and remove carbon from the atmosphere.</p>
<p>The usual advice is to plant forests near the tops of catchments, where the ground is steepest and most vulnerable. Projects such as the government’s <a href="https://www.mpi.govt.nz/forestry/funding-tree-planting-research/one-billion-trees-programme/">One Billion Trees Programme</a> are promising, but the key is to leave those trees alone, or find ways to harvest them that minimise runoff.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-zealands-maritime-territory-is-15-times-its-landmass-heres-why-we-need-a-ministry-for-the-ocean-210123">New Zealand's maritime territory is 15 times its landmass – here's why we need a ministry for the ocean</a>
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</em>
</p>
<hr>
<p>The Building Research Association of New Zealand recommends <a href="https://www.level.org.nz/health-and-safety/airborne-and-other-pollutants/sediment-and-run-off/">managing construction projects to avoid runoff</a>, including using settling ponds and channels to retain dirty water, or chemical “<a href="https://enva.com/case-studies/flocculants-in-wastewater-treatment">flocculants</a>” to make fine sediments bind together into a glob and sink. Every project should include the post-completion planting needed to retain soil.</p>
<p>Individuals and households can plant gardens and trees to avoid bare spots. They can limit the use of concrete and other impervious surfaces or choose permeable concrete. They can capture rain from their roof in a rain barrel instead of using storm water drains.</p>
<p>The Māori concept of “<a href="https://niwa.co.nz/news/ki-uta-ki-tai-niwas-role-in-mountains-to-sea-estuarine-management">ki uta ki tai</a>” recognises the connection between the land and sea, and should inform more robust and holistic environmental management policy, from the mountaintops to the deep ocean. </p>
<p>Regional councils use these words, but we need to see real action. Working together, we can keep soil on land where it belongs, and the ocean clean and clear.</p><img src="https://counter.theconversation.com/content/221966/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Abigail M Smith 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>Over 200 million tonnes of sediment are transported by rivers to the sea each year, the most widespread water contaminant in the country. Its devastating impact on marine life has to be reversed.Abigail M Smith, Professor of Marine Science, University of OtagoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2135482024-01-22T19:04:52Z2024-01-22T19:04:52ZWhen floodwater reaches the sea, it can leave a 50 metre thick layer of brown water – and cause real problems<figure><img src="https://images.theconversation.com/files/570535/original/file-20240122-20-4lzjgn.jpg?ixlib=rb-1.1.0&rect=57%2C0%2C4223%2C2848&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>Over this wet summer, Melburnians and Sydneysiders have had to think twice about cooling off at their local beach. Heavy rainfall has swollen rivers and pumped pollutants, nutrients and murky fresh water far out to sea. Swimmers at Port Phillip Bay beaches are emerging <a href="https://www.theage.com.au/politics/victoria/the-bay-has-turned-brown-and-swimmers-are-emerging-coated-in-a-strange-goo-20240118-p5ey9u.html">coated in brown goo</a>, while Sydney’s seas were contaminated <a href="https://www.smh.com.au/national/nsw/sydney-is-having-a-scorcher-think-twice-before-you-get-in-the-ocean-20240118-p5ey6a.html">last week</a>. </p>
<p>During 2022, floods repeatedly hit Australia’s eastern seaboard, causing an estimated A$3.5 billion in damage and tragic loss of life. In Sydney, it was the wettest year on record, with 2.2 metres of rain falling in the year, twice as much as usual. The heavy rainfall event in March–April dropped more than 600 millimetres of rain alone. </p>
<p>We don’t normally think about what happens to floodwater once it pulses out to sea. But we should. Floodwater is fresh. When it hits the sea in large volumes, it lowers the coastal ocean’s salinity. In our <a href="https://www.nature.com/articles/s41467-023-44398-2">new research</a>, we found floodwaters in 2022 led to 116 extreme low salinity days off Sydney – ten times more than the annual average. Extreme low salinity days are those that fall into the bottom 5% of salinity values ever measured at this location.</p>
<p>Normally, this effect clears within six days. But in 2022, extreme low salinity persisted for months in the coastal ocean. These plumes of freshwater extended as far as 70 kilometres offshore – five times further than original estimates. You could see them from space. For fish, this is confusing and dangerous. For kelp forests or sponge gardens, it can be lethal. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="satellite image of New South Wales coast with floodwaters going into sea" src="https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=501&fit=crop&dpr=1 600w, https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=501&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=501&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=630&fit=crop&dpr=1 754w, https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=630&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/570533/original/file-20240122-27-y6jvcg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=630&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Plumes of floodwater pushed far out to sea during the 2022 floods. This image shows the Hunter River on April 11 2022.</span>
<span class="attribution"><span class="source">NASA Earth Observatory</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Unprecedented floodwaters, unprecedented impact</h2>
<p>Why do we care about very low salt levels in our coastal seas? </p>
<p>First, changing salinity levels let us track where floodwaters are headed. This is important, as floodwater often carries pollutants, sediment and other contaminants from the land into the ocean. </p>
<p>Second, when large volumes of freshwater arrive, it can actually change the density of the ocean. Saltwater is heavier (more dense) than freshwater, which is why some seabirds can find a layer of drinking water far out at sea when it rains heavily.</p>
<p>The ocean’s density depends on a combination of water temperature and salinity. Off Australia’s east coast, this density is usually influenced more by temperature. But during 2022, we saw something change. For the first time, we saw the density of seawater was becoming controlled by salinity. </p>
<p>Rather than the hottest temperatures always being seen at the surface, the heat could be anywhere in the water column, as the weight (or density) of the water was mostly being controlled by how much salt it contains, not how warm it was. </p>
<p>You might look at the sea and imagine it’s the same all the way down. But in fact, there are very real changes as you go down the water column, and there are distinct layers of water. </p>
<p>What this pulse of floodwater did was change the structure and layering of the water column in unusual ways. In this coastal ocean, there’s usually a light layer of warm water at the top and colder water below it. During 2022, the normal ocean water was replaced by two additional layers of fresher water from successive floods. </p>
<p>The 50-metre deep layer of fresh water didn’t simply mix with salt. Instead, the floodwaters remained off our coastline for months, trapped between the land and the warm, swiftly flowing waters of the East Australian Current. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/whats-causing-sydneys-monster-flood-crisis-and-3-ways-to-stop-it-from-happening-again-186285">What's causing Sydney's monster flood crisis – and 3 ways to stop it from happening again</a>
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</em>
</p>
<hr>
<h2>What does freshwater do to ocean ecosystems?</h2>
<p>Some coastal species such as bream tolerate freshwater well. But others don’t like it at all. We expect the sudden appearance of a very large freshwater layer would have forced fish to move. The sediment and pollutants in the floodwaters can disrupt normal food supplies for the ocean’s inhabitants. </p>
<p>We already know floodwater can <a href="https://www.sciencedirect.com/science/article/pii/S0272771422002189?via%3Dihub">destroy kelp forests</a> or cover verdant seagrass meadows with sediment, affecting <a href="https://www.des.qld.gov.au/our-department/news-media/mediareleases/2023/great-sandy-strait-seagrass-recovering-from-floods">turtles and dugong</a>. This, in turn, can temporarily slash the catch from some fisheries. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1374550651129098243"}"></div></p>
<h2>How did we track these changes?</h2>
<p>Off the eastern coast lies an advanced network of ocean sensors, deployed as part of Australia’s <a href="https://imos.org.au/">Integrated Marine Observing System</a>. For our work, we used data from oceanographic moorings – sensors anchored to the floor and extending through the water column – as well as underwater gliders, an underwater drone packed with instruments. </p>
<p>Moorings give us detailed, consistent information but only at a few locations. Gliders travel hundreds of kilometres up and down the length of the coastline in a zigzag pattern, from the coast offshore and back, and diving from the surface to the bottom around every 200 metres. </p>
<p>We used data from moorings, gliders, satellite data and estuary monitoring sensors run by the New South Wales Department of Planning and Environment to build up a picture of where floodwaters had moved. </p>
<p>Even though we have a good system of sensors, our observing systems are geared towards monitoring temperature rather than salinity, meaning that this type of analysis can only be performed in certain parts of the coast that have the right instruments.</p>
<h2>Climate change is worsening floods. Could it weaken coastal ocean salinity?</h2>
<p>Globally, there’s little data on how salty our coastal seas are – and what floodwaters are doing, especially in areas where large rainfall is intermittent, such as eastern Australia. In 2022, severe floods also hit <a href="https://earthobservatory.nasa.gov/images/150470/flood-woes-continue-in-pakistan">Pakistan</a> and <a href="https://theconversation.com/au/topics/durban-floods-119698">South Africa</a>. </p>
<p>These regions don’t yet have ocean observing systems capable of detecting and tracking the impact of floodwaters on the ocean. We don’t know what these unprecedented floods are doing to ocean ecosystems – but it’s important we find out. </p>
<p>Extreme rainfall events are expected to <a href="https://www.nature.com/articles/nclimate2941">increase</a> globally due to climate change. We will need to determine what’s happening down there to plan our response and adapt as best we can. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-new-south-wales-reels-many-are-asking-why-its-flooding-in-places-where-its-never-flooded-before-190912">As New South Wales reels, many are asking why it's flooding in places where it's never flooded before</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/213548/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Malan receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Moninya Roughan receives funding from the Australian Research Council (ARC) and Australia's National Collaborative Research Infrastructure (NCRIS) through support of the Integrated Marine Observing System (IMOS)</span></em></p>Floodwaters pulsing into the sea normally clear within six days. But the 2022 floods in eastern Australia were different.Neil Malan, Research associate, Climate Change Research Centre, UNSW SydneyMoninya Roughan, Professor in Oceanography, UNSW SydneyLicensed 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/2184252024-01-12T13:27:51Z2024-01-12T13:27:51ZNot all carbon-capture projects pay off for the climate – we mapped the pros and cons of each and found clear winners and losers<figure><img src="https://images.theconversation.com/files/566974/original/file-20231220-29-i3lg8s.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C8500%2C5636&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Producing concrete blocks with captured carbon, like these in Brooklyn, NY., has both economic and climate benefits.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/ClimateDecarbonizingBuildings/7719f5a25a9e4b1c89afd7eef7a37e58/photo">AP Photo/John Minchillo</a></span></figcaption></figure><p>Capturing carbon dioxide from the air or industries and recycling it can sound like a win-win climate solution. The greenhouse gas stays out of the atmosphere where it can warm the planet, and it avoids the use of more fossil fuels.</p>
<p>But not all carbon-capture projects offer the same economic and environmental benefits. In fact, some can actually worsen climate change.</p>
<p>I <a href="https://volker-sick.engin.umich.edu/">lead the Global CO₂ Initiative</a> at the University of Michigan, where my colleagues and I study how to put captured carbon dioxide (CO₂) to use in ways that help protect the climate. To help figure out which projects will pay off and make these choices easier, we <a href="https://doi.org/10.3389/fclim.2023.1286588">mapped out the pros and cons</a> of the most common carbon sources and uses.</p>
<h2>Replacing fossil fuels with captured carbon</h2>
<p>Carbon plays a crucial role in many parts of our lives. Materials such as fertilizer, aviation fuel, textiles, detergents and much more depend on it. But years of research and the climate changes the world is already experiencing have made <a href="https://www.ipcc.ch/report/ar6/syr/">abundantly clear</a> that humanity needs to urgently end the use of fossil fuels and remove the excess CO₂ from the atmosphere and oceans that have resulted from their use.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of a landscape shows how greenhouse gases and released, captured and stored in various ways, including oceans, land, forests and human activities." src="https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=272&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=272&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=272&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=342&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=342&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566951/original/file-20231220-29-qulhfw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=342&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Balancing the environmental carbon budget is complex, and active carbon management is necessary to stabilize the climate.</span>
<span class="attribution"><span class="source">University of Michigan</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Some carbon materials can be replaced with carbon-free alternatives, such as using renewable energy to produce electricity. However, for other uses, such as aviation fuel or plastics, carbon will be harder to replace. For these, technologies are being developed to <a href="https://doi.org/10.52548/KCTT1279">capture and recycle carbon</a>.</p>
<p><a href="http://www.globalco2initiative.org/">Capturing excess CO₂</a> – from the oceans, atmosphere or industry – and using it for new purposes is called <a href="https://www.iea.org/reports/ccus-in-clean-energy-transitions">carbon capture, utilization and sequestration</a>, or CCUS. Of all the options to handle captured CO₂, my colleagues and I favor using it to make products, but let’s examine all of them.</p>
<h2>CCUS best and worst cases</h2>
<p>With each method, the combination of the source of the CO₂ and its end use, or disposition, determines its environmental and <a href="https://doi.org/10.7302/5826">economic consequences</a>.</p>
<p>In the best cases, the process will leave less CO₂ in the environment than before. A strong example of this is using captured CO₂ to produce construction materials, such as concrete. It seals away the captured carbon and creates a product that has economic value.</p>
<p><iframe id="A5bka" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/A5bka/11/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>A few methods are carbon-neutral, meaning they add no new CO₂ to the environment. For example, when using CO₂ captured from the air or oceans and turning it into fuel or food, the carbon returns to the atmosphere, but the use of captured carbon avoids the need for new carbon from fossil fuels. </p>
<p>Other combinations, however, are harmful because they increase the amount of excess CO₂ in the environment. One of the most common underground storage methods – enhanced oil recovery – is a prime example.</p>
<h2>Underground carbon storage pros and cons</h2>
<p>Projects for years have been capturing excess CO₂ and <a href="https://www.globalccsinstitute.com/resources/global-status-of-ccs-2022/">storing it underground in natural structures</a> of porous rock, such as deep saline reservoirs, basalt or depleted oil or gas wells. This is called carbon capture and sequestration (CCS). If done right, geologic storage can durably remove large amounts of CO₂ from the atmosphere.</p>
<p>When the CO₂ is captured from air, water or biomass, this creates a carbon-negative process – less carbon is in the air afterward. However, if the CO₂ instead comes from new fossil fuel emissions, such as from a coal- or gas-fired power plant, carbon neutrality isn’t possible. <a href="https://doi.org/10.1007/978-1-4614-2215-0">No carbon-capture technology works at 100% efficiency</a>, and some CO₂ will always escape into the air.</p>
<p>Capturing CO₂ is also expensive. If there is no product to sell, underground storage <a href="https://www.iisd.org/articles/deep-dive/why-carbon-capture-storage-cost-remains-high">can become a costly service</a> ultimately covered by taxes or fees, similar to <a href="https://doi.org/10.1098/rsfs.2020.0010">paying for trash disposal</a>.</p>
<p><iframe id="xQEcl" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/xQEcl/1/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
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<p>One way to lower the cost is to sell the captured CO₂ for <a href="https://www.iea.org/commentaries/can-co2-eor-really-provide-carbon-negative-oil">enhanced oil recovery</a> – a common practice that pumps captured CO₂ into oil fields to push more oil out of the ground. While most of the CO₂ is expected to stay underground, the result is more fossil fuels that will eventually send more carbon dioxide into the atmosphere, eliminating the environmental benefit.</p>
<h2>Using captured carbon for food and fuel</h2>
<p>Short-lived materials made from CO₂ include <a href="https://www.iata.org/en/programs/environment/sustainable-aviation-fuels/">aviation fuels</a>, <a href="https://doi.org/10.1016/j.jcou.2021.101726">food</a>, <a href="https://www.aspirin-foundation.com/history/chemistry/">drugs</a> and <a href="https://doi.org/10.1016/j.jmatprotec.2013.10.003">working fluids</a> used in machining metals. These items aren’t particularly durable and will soon decompose, releasing CO₂ again. But the sale of the products yields economic value, helping pay for the process.</p>
<p>This CO₂ can be captured from the air again and used to make a future generation of products, which would create a sustainable, essentially <a href="https://www.energy.gov/fecm/articles/co2-recycling-technology-limits-opportunities-and-policies-circular-carbon-economy">circular carbon economy</a>. However, this only works if the CO₂ is captured from the air or oceans. If the CO₂ comes from fossil fuel sources instead, this is new CO₂ that will be added to the environment when the products decompose. So even if it is captured again, it will worsen climate change.</p>
<h2>Storing carbon in materials, such as concrete</h2>
<p>Some minerals and waste materials can convert CO₂ to limestone or other rock materials. The long-lived materials created this way can be very durable, with <a href="https://doi.org/10.3389/fclim.2022.878756">lifetimes of longer than 100 years</a></p>
<p>A good <a href="https://theconversation.com/bendable-concrete-and-other-co2-infused-cement-mixes-could-dramatically-cut-global-emissions-152544">example is concrete</a>. CO₂ can react with particles in concrete, causing it to <a href="https://www.usgs.gov/news/featured-story/making-minerals-how-growing-rocks-can-help-reduce-carbon-emissions">mineralize into solid form</a>. The result is a useful product that can be sold instead of being stored underground. Other durable products include aggregates used in road construction, carbon fiber used in automotive, aerospace and defense ]applications and some polymers.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EcJWiy8Tvoc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Volker Sick, director of the Global CO₂ Initiative at the University of Michigan and author of this article, discusses why carbon capture and its use has been slow to gain attention.</span></figcaption>
</figure>
<p>These materials provide the best combination of environmental impact and economic benefit when they are made with CO₂ captured from the atmosphere rather than new fossil fuel emissions.</p>
<h2>Choose your carbon projects wisely</h2>
<p>CCUS can be a useful solution, and governments have started <a href="https://www.energy.gov/articles/biden-harris-administration-announces-1.2-billion-nations-first-direct-air-capture">pouring billions of dollars</a> into its development. It must be closely monitored to ensure that carbon-capture technologies will not delay fossil fuel phaseout. It is an all-hands-on-deck effort to take the best combinations of CO₂ sources and disposition to achieve rapid scaling at an affordable cost to society.</p>
<p>Because climate change is such a complex problem that is harming people throughout the world, as well as future generations, I believe it is imperative that actions are not only fast, but also well thought out and based in evidence.</p>
<p><em>Fred Mason, Gerry Stokes, Susan Fancy and Stephen McCord of the Global CO₂ Initiative contributed to this article.</em></p><img src="https://counter.theconversation.com/content/218425/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Volker Sick receives funding from the Grantham Foundation for the Preservation of the Environment.</span></em></p>The combination of the source of the CO₂ and its end use determines its environmental and economic benefits or consequences.Volker Sick, Professor of Advanced Energy Research, Director of the Global CO2 Initiative, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2189022024-01-11T13:25:55Z2024-01-11T13:25:55ZTo protect endangered sharks and rays, scientists are mapping these species’ most important locations<figure><img src="https://images.theconversation.com/files/565884/original/file-20231214-27-kjjzka.jpg?ixlib=rb-1.1.0&rect=60%2C0%2C6720%2C4426&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A tiger shark swims among surgeonfish off Fuvahmulah Atoll, Maldives, in the Indian Ocean.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/tiger-shark-with-shoal-of-fish-surgeonfishes-indian-royalty-free-image/1262279323">imageBROKER/Norbert Probst via Getty Images</a></span></figcaption></figure><p>All of the saltwater bodies on Earth make up <a href="https://oceanservice.noaa.gov/facts/howmanyoceans.html">one big ocean</a>. But within it, there is infinite variety – just ask any scuba diver. Some spots have more coral, more sea turtles, more fish, more life. </p>
<p>“I’ve been diving in many places around the world, and there are few locations like the <a href="https://visitfuvahmulah.mv/discover-fuvahmulah/">Fuvahmulah Atoll</a> in the Maldives,” Amanda Batlle-Morera, a research assistant with the <a href="https://sharkrayareas.org/">Important Shark and Ray Areas project</a>, told me. “You can observe tiger sharks, thresher sharks, scalloped hammerheads, oceanic manta rays and more, without throwing out bait to attract them.” </p>
<p>Identifying areas like Fuvahmulah that are especially important to certain species is a <a href="https://www.fws.gov/sites/default/files/documents/critical-habitat-fact-sheet.pdf">long-standing strategy</a> for protecting threatened land animals, birds and marine mammals, such as whales and dolphins. Now our team of marine conservation scientists at the <a href="https://sharkrayareas.org/">Important Shark and Ray Areas project</a> is using it to help protect sharks and their relatives. </p>
<p>I am a <a href="https://scholar.google.com/citations?user=xb7noGAAAAAJ&hl=en">marine conservation biologist</a> and the project’s communications officer. This initiative is working to identify locations that are critical for sharks and rays, so that these zones can be flagged for future protection or fisheries management measures. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0mPBvhGvZLI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Divers get close views of tiger sharks at Fuvahmulah, an offshore island in the southern Maldives. Six threatened shark species and one threatened ray species appear regularly in the area.</span></figcaption>
</figure>
<h2>Where the sharks are</h2>
<p>Sharks and their relatives are some of the most imperiled animals on Earth: More than one-third of all known species are <a href="https://doi.org/10.1016/j.cub.2021.08.062">threatened with extinction</a>. Many of these animals play vital roles in their ecosystems. Losing marine predators <a href="https://doi.org/10.1016/j.tree.2008.01.003">can destabilize entire food webs</a> and the ecosystems that these food webs depend on.</p>
<p>In recent years, the management of sharks and their relatives, rays and chimaeras, has largely focused on curbing the impacts of fisheries and trade on these species. But their populations <a href="https://doi.org/10.1016/j.cub.2021.08.062">are still declining rapidly</a>, so new strategies are needed. </p>
<p>To effectively protect these important and threatened animals, my colleagues and I believe it is vital to identify and protect parts of the ocean, plus some freshwater habitats, that are especially significant for their lives. Some areas, for example, are important migratory pathways, or feeding or mating grounds, or places to lay eggs. </p>
<p>Our team has created a <a href="https://doi.org/10.3389/fmars.2022.968853">list of technical criteria</a> so that zones around the world can be examined and potentially designated as Important Shark and Ray Areas. We modeled these criteria on similar approaches that are already in use, such as <a href="https://doi.org/10.1641/0006-3568(2004)054%5B1110:KBAASC%5D2.0.CO;2">important marine mammal areas</a>, which we adapted to the specific needs and biology of sharks and their relatives. </p>
<p>We are now hosting a series of 13 regional workshops around the world and inviting local experts to nominate preliminary areas of interest for evaluation by our team and an independent expert review panel. So far, we’ve completed three workshops, one focusing on the Central and South American Pacific, another on the Mediterranean and Black seas, and the third on the Western Indian Ocean, with a workshop for Asia planned for early 2024. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A world map shows zones that scientists have identified as Important Shark and Ray Areas in the Pacific and Indian oceans and the Mediterranean Sea." src="https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=387&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=387&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568049/original/file-20240105-14-7s4g8o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=387&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 current version of the online atlas of Important Shark and Ray Areas. The atlas is organized by region, showing which parts of the world’s oceans and coasts have been assessed.</span>
<span class="attribution"><a class="source" href="https://sharkrayareas.org/">Important Shark and Ray Areas initiative</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>After the workshops and expert reviews, each finalized Important Shark and Ray Area will be added to our e-atlas, which <a href="https://sharkrayareas.org/e-atlas/">can be viewed online</a>. Each region’s Important Shark and Ray Areas are published in a formal compendium, and the whole global process will be repeated every 10 years. This cycle will allow us to consider changes to areas that have already been mapped, such as new fishery policies or impacts from climate change, and to take into account new research that can help us identify new areas. </p>
<h2>Informing conservation policies</h2>
<p>We recently published our <a href="https://sharkrayareas.org/download/mediterranean-and-black-seas-regional-compendium-of-important-shark-and-ray-areas/">Mediterranean and Black seas region compendium</a>, which reflects input from over 180 experts from around the region. It identifies 65 Important Shark and Ray Areas that range widely in size and habitat type. Our <a href="https://sharkrayareas.org/download/western-indian-ocean-regional-compendium-of-important-shark-and-ray-areas/">western Indian Ocean compendium</a> includes over 125 areas. </p>
<p>These zones are important for species like the critically endangered <a href="https://www.fisheries.noaa.gov/species/blackchin-guitarfish">blackchin guitarfish</a> (<em>Glaucostegus cemiculus</em>), as well as heavily fished shark species like the <a href="https://www.sharks.org/smoothhound-mustelus-mustelus">common smoothhound shark</a> (<em>Mustelus mustelus</em>). </p>
<p>Some of these areas, such as <a href="https://sharkrayareas.org/portfolio-item/benidorm-island-isra/">Benidorm Island</a> off Spain’s Mediterranean coast, are in shallow coastal zones. Others, like the <a href="https://sharkrayareas.org/wp-content/uploads/isra-factsheets/12CentralSouthPacific/Cocos-Galapagos-Swimway-12CentralSouthPacific.pdf">Cocos-Galapagos Swimway</a> off Costa Rica and Ecuador, reach into deep ocean waters. </p>
<p>The smallest area identified so far, Israel’s <a href="https://sharkrayareas.org/wp-content/uploads/isra-factsheets/03MedBlackSeas/Palmahim-Brine-Pools-03MedBlackSeas.pdf">Palmahim brine pools</a> in the southeast Mediterranean, measures just 0.03 square miles (0.09 square kilometers) – about half the size of New York City’s Grand Central station. <a href="https://eol.org/pages/46560072">Blackmouth catsharks</a>
(<em>Galeus melastomus</em>) breed and lay eggs there, and threatened <a href="https://eol.org/pages/46560287">angular rough sharks</a> (<em>Oxynotus centrina</em>) feed there, including on blackmouth catshark eggs. </p>
<p>The largest area is the <a href="https://sharkrayareas.org/wp-content/uploads/isra-factsheets/03MedBlackSeas/Strait-of-Sicily-and-Tunisian-Plateau-03MedBlackSeas.pdf">Strait of Sicily and Tunisian Plateau</a>, which extends over 77,000 square miles (200,000 square kilometers) – about the size of Great Britain – in the Mediterranean between Sicily, Malta, western Libya and Tunisia. This zone supports at least 32 species of sharks, rays and chimaeras, including many that are at risk of extinction, in habitats ranging from shallow seagrass beds to deep ocean trenches.</p>
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<p>Identifying a location as an Important Shark and Ray Area does not mean it will automatically be protected. Our goal is to inform countries’ existing spatial planning and fisheries management processes and other conservation planning. Eventually, these zones may be incorporated into <a href="https://oceanexplorer.noaa.gov/facts/mpas.html">marine protected areas</a> or other types of ocean preserves.</p>
<p>Sharks and their relatives need human help to survive and maintain their important biological roles in the ocean. Through the Important Shark and Ray Areas project, hundreds of scientists and other experts are helping to identify special places for these species that we believe need some extra attention.</p>
<p><em>Dr. Rima Jabado, chair of the IUCN Species Survival Commission Shark Specialist Group, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/218902/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Shiffman 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>A new initiative is pinpointing areas in the world’s oceans that are key habitats for sharks and their relatives, so that governments can consider protecting these areas.David Shiffman, Faculty Research Associate in Marine Biology, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.