tag:theconversation.com,2011:/id/topics/shark-conservation-29526/articlesShark conservation – The Conversation2023-07-13T20:56:33Ztag:theconversation.com,2011:article/2062852023-07-13T20:56:33Z2023-07-13T20:56:33ZReversing the decline in shark and ray populations is possible, but requires strong governance and management<figure><img src="https://images.theconversation.com/files/531993/original/file-20230614-17-l5ljpl.jpg?ixlib=rb-1.1.0&rect=190%2C539%2C1358%2C815&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sharks and rays are rapidly declining globally, and their situation is representative of many other exploited marine species that lack scientific monitoring.</span> <span class="attribution"><span class="source">(Carlos Diaz/Ocean Image Bank)</span></span></figcaption></figure><p>The oceans remain vast and inscrutable. While technology has revolutionized our capacity to track threats to biodiversity on land, our understanding of the status of marine biodiversity remains <a href="https://doi.org/10.1126/science.abj0211">fragmented and biased toward economically high-valued species</a>. </p>
<p><a href="https://doi.org/10.1111/faf.12593">Most fish species are not scientifically monitored</a>, which is done by collecting and analyzing population data. Global marine fish catches continue to be underestimated, with as much as <a href="https://doi.org/10.1038/ncomms10244">one-third missing</a>.</p>
<p>The fast decline of shark and ray species globally is representative of many other exploited marine species that lack scientific monitoring and <a href="https://doi.org/10.1016/j.ocecoaman.2019.104994">a general political will for fisheries management</a>. </p>
<p><a href="https://doi.org/10.1038/s41586-020-03173-9">Seventy-one per cent of oceanic shark and ray populations have been depleted in the last half-century</a> and <a href="https://doi.org/10.1016/j.cub.2021.08.062">one-third of all 1,199 shark and ray species are now threatened with extinction</a>, based on the International Union for Conservation of Nature (IUCN) criteria, primarily due to overfishing. These species have a key role in marine ecosystem functioning and human food security.</p>
<p>Fortunately, there are signs of hope. New scientific techniques and recent efforts of the scientific community have helped create a more comprehensive picture of the speed and scale of these changes, highlighting successful cases of protection and management efforts, including those in <a href="https://doi.org/10.1016/j.cub.2016.12.017">Australia, New Zealand, the United States, Canada and the European Union</a>.</p>
<h2>Coastal sharks and rays missing in some areas, thrive in others</h2>
<p>In 2019, our team of experts carried out IUCN Red List assessments in the Bahamas to determine the global extinction risk status of several sharks and rays.</p>
<p>We found ourselves attempting to reconcile widely divergent views of the regional status of species that were more common in the northwest Atlantic and rare or near absent in the southwest Atlantic.</p>
<p>To understand the reasons for this difference, we gathered data on population status of all 26 coastal sharks and rays — ranging from north to south — across the western Atlantic Ocean, examining the factors like fishing pressure and management effort that could influence the extinction risk status of these species.</p>
<p>We found that <a href="https://doi.org/10.1073/pnas.2216891120">populations of the same species had collapsed in the southwest Atlantic due to unrestrained fishing</a>. Across the whole region, we saw that although fishing pressure increased extinction risk, the strength of management engagement was widely overlooked, despite it reducing the extinction risk of all 26 wide-ranging sharks and rays. </p>
<p>The bonnethead shark species (<em>Sphyrna tiburo</em>) is an excellent <a href="https://www.iucnredlist.org/species/39387/205765567#population">example</a> of what is happening in the Western Atlantic region. The species is abundantly found in the northern part of its range. But further south, it hasn’t been seen in decades.</p>
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<img alt="A bonnethead shark swims in green waters" src="https://images.theconversation.com/files/537189/original/file-20230713-25-7ws8w7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537189/original/file-20230713-25-7ws8w7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537189/original/file-20230713-25-7ws8w7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537189/original/file-20230713-25-7ws8w7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537189/original/file-20230713-25-7ws8w7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537189/original/file-20230713-25-7ws8w7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537189/original/file-20230713-25-7ws8w7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&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">Abundantly found in the northern Atlantic waters, bonnethead sharks are no longer seen in the south.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>So, why is this happening?</p>
<p>In the United States, this shark species is managed by catch quota, while in Mexico there is a seasonal fishery quota. The Bahamas has been dubbed a ‘<a href="https://oceanographicmagazine.com/features/true-value-shark-sanctuaries/">shark sanctuary</a>’ because of their ban on commercial shark fishing.</p>
<p>Further south, there is no discernible management and this species is captured in unregulated targeted fisheries and as retained incidental catch. Down south, this species is likely subject to heavy unmanaged fishing pressure in most countries. It is very rarely found in Colombia and has collapsed in Brazil where there are very few recent records.</p>
<h2>A road map for shark recovery</h2>
<p>The <a href="https://www.fisheries.noaa.gov/sustainable-fisheries/atlantic-shark-fisheries-management-highlights-timeline#1993">U.S. Fishery Management Plan for Sharks of the Atlantic Ocean</a> was implemented by the National Oceanic and Atmospheric Administration in 1993.</p>
<p>This plan was developed in response to the <a href="https://www.fisheries.noaa.gov/sustainable-fisheries/atlantic-shark-fisheries-management-highlights-timeline#1976">intense expansion of commercial and recreational fisheries in the 1970s to 1980s due to the increased global demand for shark meat, fins and cartilage as well as the concerns about their effects on shark populations</a>.</p>
<p>We found that populations in the northwest Atlantic recovered shortly after the implementation of this management plan.</p>
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<img alt="A pile of fish." src="https://images.theconversation.com/files/531984/original/file-20230614-15-yyoovi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/531984/original/file-20230614-15-yyoovi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531984/original/file-20230614-15-yyoovi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531984/original/file-20230614-15-yyoovi.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531984/original/file-20230614-15-yyoovi.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531984/original/file-20230614-15-yyoovi.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531984/original/file-20230614-15-yyoovi.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">
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<span class="caption">Requiring sharks to be brought ashore with fins attached as per the Shark Conservation Act of 2010 vastly improved species identification and the quality of data, providing a better means for enforcing regulations.</span>
<span class="attribution"><span class="source">(NOAA Fisheries)</span>, <span class="license">Author provided</span></span>
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<p>Thirty years after this implementation, we found the stabilization of three populations. We also documented the rebuilding population of six of the 11 coastal sharks here. </p>
<p>We believe that this success can be attributed to:</p>
<ul>
<li><p>A strong regulation system where catch is prohibited for some species (or group of species) and limited for others. A system that improves catch reporting and reduces the pressure of fishing through the reduction of the number of shark-directed fishing permits.</p></li>
<li><p>strict enforcement by the U.S. Coast Guard and law enforcement agencies for fishers in U.S. waters</p></li>
<li><p>continuous monitoring of the fishery for data collection</p></li>
</ul>
<h2>Recovering species population through collaboration</h2>
<p>Our research found that halting and reversing declines and creating sustainable fisheries is possible even for wide-ranging sharks and rays.</p>
<p>But this requires strong governance and management.</p>
<p>Concerted efforts can bridge the spots of successful management and recovery with adjacent nations where the species are still in decline, leading to success at a global scale. This approach will ensure that successful conservation in one country is not undone by less regulated fishing areas outside those borders.</p>
<p>Developed nations, that are bringing their fisheries into sustainability and importing more fish, should translate their successes into capacity-building lessons to support other nations undergoing the transition towards sustainability.</p><img src="https://counter.theconversation.com/content/206285/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This work was funded by the Shark Conservation Fund as part of the Global Shark Trends Project</span></em></p>Through regulation, enforcement and monitoring, fisheries management can lead to recoveries in shark and ray populations.Nathan Pacoureau, Postdoctoral Research Fellow, Global Shark Trends Project, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1962312022-12-12T13:02:44Z2022-12-12T13:02:44ZShark fishing is a global problem that demands local solutions<p>Countries from around the world have <a href="https://www.theguardian.com/environment/2022/nov/18/shark-fin-trade-regulation-cites-panama">voted</a> to limit the global trade in sharks under the Convention on International Trade in Endangered Species (<a href="https://cites.org/eng">Cites</a>). Trade in shark products is a major driver of shark overfishing, leading to the deaths of millions of sharks every year. The new Cites listings aim to keep the international trade of 54 species of shark and ray within sustainable limits.</p>
<p>But there are concerns that Cites listings could unintentionally drive up the price of shark fins and lead to the development of informal shark fin markets. Catches of many species already listed on Cites remain <a href="https://conbio.onlinelibrary.wiley.com/doi/10.1111/csp2.494">valuable</a> for small-scale fishers. And in 2018, <a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/conl.12457">Cites-listed sharks</a> remained among the leading species traded in contemporary fin markets. </p>
<p>Yet targeted fishing is just part of the issue. Sharks are frequently caught as <a href="https://www.sciencedirect.com/science/article/abs/pii/S0308597X14003546?via%3Dihub">unintentional bycatch</a> by fishers using unselective nets and lines. And since Cites only pertains to international trade, many sharks that are traded and consumed in local or domestic markets are not covered by the regulations. Strict rules protecting sharks in these markets could negatively impact the livelihoods of the small-scale fisheries that depend on them for food and income.</p>
<p>Interventions to reduce catches of threatened shark species must support the rights and welfare of small-scale fishers and be perceived as legitimate. My colleagues and I conducted <a href="https://www.sciencedirect.com/science/article/pii/S0006320722003743?via%3Dihub">research</a> on small-scale fisheries in Indonesia – the world’s <a href="https://www.fao.org/3/i4795e/i4795e.pdf">largest shark fishing nation</a>. </p>
<h2>Fishery-led conservation</h2>
<p>We focused on two taxa, hammerhead sharks and wedgefish. These taxa are both critically endangered and already listed on Cites. </p>
<p>Applying research methods from behavioural science and economics, we interviewed 144 fishers from two villages in the Indonesian shark fishing hotspots of Aceh and Lombok. We presented fishers with a range of conservation scenarios and asked them how their fishing behaviour would change under each.</p>
<p>The first scenario involved the introduction of a new rule stipulating that particular species could not be legally caught or brought to shore. The rule was accompanied with a fine for non-compliance. </p>
<p>The second was a voluntary programme to protect the species. Fishers could choose to reduce their catch or release accidentally caught sharks rather than have a rule imposed on them. </p>
<p>The third approach was based on compensation. Fishers would receive payments for reducing their catch of endangered sharks equivalent to the value they could otherwise have received for it.</p>
<p>For scenarios that involved monetary incentives, we asked fishers to indicate how much they would be willing to pay to continue fishing for endangered sharks or how much they would accept to reduce their catch. We then asked fishers to explain why they would (or why they would not) change their behaviour and how they planned to reduce their catch. </p>
<h2>Support for financial compensation</h2>
<p>The rule and fine scenario was unpopular among the interviewed fishers. Only 50% of those interviewed in Lombok and 20% in Aceh said they would reduce catches in response to the rule and fine scheme. They felt it was impractical, unfair and would negatively impact their welfare due to reducing their income and eliminating a key source of food.</p>
<p><a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/conl.12725">Research</a> suggests that if conservation rules are not accepted by local fishers, then they often fail to have a meaningful effect on fisher behaviour.</p>
<p>The voluntary programme was more popular. 55% of fishers in Aceh stated they would voluntarily stop catching wedgefish.</p>
<p>But the fishers expressed a strong preference for a programme based on compensation. 98% of all fishers interviewed said they would stop catching hammerheads while 96% said they would stop catching wedgefish if their lost income was compensated for. Fishers in Aceh were willing to accept less than US$2 (£1.63) per hammerhead shark and US$4-7 (£3.27–5.72) per wedgefish.</p>
<p>Based on data from our study, we estimate that it would cost just US$12,000 (£9,800) per year to save up to 20,000 hammerheads and wedgefish in Aceh.</p>
<p>Although not tested by our study, an approach based on compensation is likely to be more cost-effective than interventions that require enforcement. The exact cost of enforcing a rule and fine policy in Indonesia is unknown, but the annual cost of a single marine patrol boat in the USA is between <a href="https://www.cga.ct.gov/2010/ofarpt/2010OFA-0207.htm">US$40,000 and 100,000 (£32,600 and 81,000)</a>. </p>
<p>The fishers also felt that a compensation scheme was fair and would deliver positive social outcomes for their villages. </p>
<p>We are now <a href="https://www.instagram.com/kebersamaan_untuk_lautan/">trialling</a> such a scheme at the two sites in Aceh and Lombok. Fishers receive financial compensation if they share a video of the safe release of hammerheads or wedgefish. More than 150 animals have been <a href="https://www.youtube.com/watch?v=v1RdxFM5NzI">safely released</a> since April and fishers have so far reported using the payments to support their families and send their children to school.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/v1RdxFM5NzI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Successful releases of hammerhead sharks and wedgefish caught as bycatch in Indonesia.</span></figcaption>
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<h2>Broader implications</h2>
<p>One size fits all shark conservation measures, based on the enforcement of rules, fail to account for the diversity of fishing contexts and their socio-economic challenges. Cites listings can play a part in supporting the recovery of threatened shark species by better regulating international trade. But nuanced management measures are also needed to reduce catches in the context of limiting harm to small-scale fishing communities.</p>
<p>Governments are expected to agree on a <a href="https://www.cbd.int/article/draft-1-global-biodiversity-framework">new global framework</a> to protect and restore nature at the UN biodiversity summit <a href="https://www.cbd.int/conferences/2021-2022">COP15</a> this month. The long-term vision of this framework is “living in harmony with nature”.</p>
<p>Our research, in line with this vision, offers a scalable method for designing conservation interventions that are appropriate for different fishing contexts. More importantly, it supports the development of solutions that involve the people most affected by conservation.</p><img src="https://counter.theconversation.com/content/196231/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hollie Booth receives funding from Save Our Seas Foundation and the Society for Conservation Biology. </span></em></p>Countries have voted to limit the international shark trade, but this fails to account for the diversity in fishing contexts around the world.Hollie Booth, Nature Positive Senior Specialist at The Biodiversity Consultancy, and Post-Doc Research Associate, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1933952022-10-31T19:01:45Z2022-10-31T19:01:45ZSurfers share their waves with sharks, but fear not<p>Surfers have a complex relationship with sharks. Many surfers, either knowingly or not, share their waves with sharks of various shapes and sizes. On rare occasions these interactions can result in bites or close calls.</p>
<p>A highly publicised close call involved Australian surfer Mick Fanning and a white shark during the 2015 World Surf League final at Jeffreys Bay in South Africa. A <a href="https://www.youtube.com/watch?v=z4wGSi9FXak">video</a> of this interaction has over 19 million views on YouTube alone. Others tune into Hollywood films such as <a href="https://en.wikipedia.org/wiki/Soul_Surfer_(film)">Soul Surfer</a>, which tells the story of surfer Bethany Hamilton who lost her arm to a tiger shark in Hawaii. </p>
<p>Shark bites on humans are rare. Worldwide, there were 112 confirmed bites in 2021 on the <a href="https://www.floridamuseum.ufl.edu/shark-attacks/yearly-worldwide-summary/">International Shark Attack File</a>, with nine unprovoked bites resulting in fatalities. When shark bites occur, often surfers are involved because they are frequently in the ocean. Despite this, many surfers appear to accept these interactions as simply a part of surfing. </p>
<p>Surfers even refer to certain sharks as “locals” at particular breaks. In many places, surfers use the term “<a href="https://www.abc.net.au/local/stories/2012/07/03/3537702.htm">men in grey suits</a>” when sharks are present. Authors of a <a href="https://www.mdpi.com/2071-1050/11/11/3114">2019 study</a> in California explain this euphemism is used to alert surfers that sharks are present without causing anxiety or stress. </p>
<p>A <a href="https://www.sciencedirect.com/science/article/pii/S0308597X22003074">new study</a> published in Marine Policy surveyed 391 surfers across 24 different countries (predominantly the United States). The study found 60% of surfers are not afraid of sharks despite 52% having seen sharks while surfing. And 17% said either they or someone they knew had been bitten by a shark. </p>
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Read more:
<a href="https://theconversation.com/how-shoring-up-drones-with-artificial-intelligence-helps-surf-lifesavers-spot-sharks-at-the-beach-192498">How shoring up drones with artificial intelligence helps surf lifesavers spot sharks at the beach</a>
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<h2>Why aren’t surfers afraid?</h2>
<p>This study of the complex but little-researched relationship between surfers and sharks offers interesting insight into the perception of risk. </p>
<p>In general, most people have no direct experience with sharks, yet overestimate the chance of encountering one and have a strong fear of them. Many surfers have had direct encounters with sharks but perceive the risk to be low and aren’t afraid of them. In fact, 44% of surfers said they would still go into the water if a shark was sighted.</p>
<p>The psychology of cognitive heuristics – or shortcuts in thinking – can help us explain why surfers aren’t afraid of sharks. </p>
<p>The behavioural psychology principle of operant conditioning explains how consequences influence behaviours. For surfers who have encountered a shark but have not been bitten or had a close call, this behaviour of surfing with sharks (and not being afraid) is being reinforced. </p>
<p>Perhaps this lower level of fear is influenced by a consistent personality trait. <a href="https://www.tandfonline.com/doi/full/10.1080/08927936.2021.1986260?scroll=top&needAccess=true">Research</a> has found people high in sensation-seeking, which is the tendency for people to pursue thrill-seeking experiences, view the risks of sharks as lower. It is plausible that many surfers are high on sensation-seeking, which may help explain why they perceive the risk of sharks to be low. </p>
<p>Post-rationalisation, or choice-support bias, is the tendency for people to ascribe positive attributes to a decision they have made, essentially to justify the decision. Surfers may downplay their fear of sharks to rationalise their decision to continue to surf, as their desire to surf is greater than their perceived risk of a shark bite.</p>
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Read more:
<a href="https://theconversation.com/shark-bites-are-rare-here-are-8-things-to-avoid-to-make-them-even-rarer-173746">Shark bites are rare. Here are 8 things to avoid to make them even rarer</a>
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<h2>How does this affect shark conservation?</h2>
<p>Globally, it’s estimated humans <a href="https://www.sharkconservation.org.au/">kill 100 million sharks</a> each year. A quarter of all shark species are now threatened with extinction, so actions to protect them are important. </p>
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<p>Given the general public’s fear of sharks is a barrier to shark conservation, understanding surfers’ shark fears (or lack thereof) gives us an important insight into fear and perception of risk. This will further our understanding of these complicated psychological factors.</p>
<p>In the discussion of shark conservation, the many relevant groups include politicians, fishers, the media and scientists. But frequent ocean users such as surfers are often overlooked, despite being more likely to interact with sharks than others. </p>
<p>Giving this cohort a weighted voice in the discussion of shark management and reducing the risks of shark bite will ensure a better, more logical balance between safety and conservation.</p>
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Read more:
<a href="https://theconversation.com/sydney-shark-attack-triggers-calls-for-a-cull-but-lets-take-a-deep-breath-and-look-at-the-evidence-177357">Sydney shark attack triggers calls for a cull – but let's take a deep breath and look at the evidence</a>
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<p class="fine-print"><em><span>Brianna Le Busque 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>Many surfers have seen sharks while surfing in the ocean. Yet, unlike the general public, 60% are not afraid of sharks. It’s a finding that offers an insight into attitudes to shark conservation.Brianna Le Busque, Lecturer in Psychology, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1434392020-07-30T19:59:29Z2020-07-30T19:59:29ZSharks are thriving at the Kermadec Islands, but not the rest of New Zealand, amid global decline<figure><img src="https://images.theconversation.com/files/350296/original/file-20200729-19-wlnazh.jpg?ixlib=rb-1.1.0&rect=183%2C0%2C1733%2C1074&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>A <a href="https://www.nature.com/articles/s41586-020-2519-y">recent global assessment</a> of shark populations at 371 coral reefs in 58 countries found no sharks at almost 20% of reefs and alarmingly low numbers at many others. </p>
<p>The study, which involved over 100 scientists under the <a href="https://globalfinprint.org/">Global FinPrint</a> project, gave New Zealand a good score card. But because it focused on coral reefs, it included only one region — Rangitāhua (Kermadec Islands), a pristine subtropical archipelago surrounded by New Zealand’s <a href="https://www.doc.govt.nz/parks-and-recreation/places-to-go/northland/places/kermadec-islands/">largest marine reserve</a>. </p>
<p>It is a different story around the main islands of New Zealand. Many coastal shark species may be in decline, and less than half a percent of territorial waters is protected by marine reserves.</p>
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<figcaption><span class="caption">The first global survey of reef sharks shows they are virtually absent in many areas.</span></figcaption>
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Read more:
<a href="https://theconversation.com/scientists-at-work-uncovering-the-mystery-of-when-and-where-sharks-give-birth-136673">Scientists at work: Uncovering the mystery of when and where sharks give birth</a>
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<h2>Sharks in Aotearoa</h2>
<p>In New Zealand, there are <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.3053">more than a hundred species</a> of sharks, rays and chimaeras. They belong to a group of fishes called chondrichthyans, which have skeletons of cartilage instead of bone. </p>
<p>Some 55% of New Zealand’s chondrichthyan species are listed as “not threatened” by the International Union for Conservation of Nature (<a href="https://www.iucn.org/">IUCN</a>). Not so encouraging is the 32% of species listed as “data deficient”, meaning we don’t know the status of their populations. Most species (77%) live in waters deeper than 200 metres. </p>
<p>Seven species are <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.3053">fully protected</a> under the <a href="https://www.doc.govt.nz/about-us/our-role/legislation/wildlife-act/">Wildlife Act 1953</a>. They are mostly large, migratory species such as the <a href="https://blog.doc.govt.nz/2019/03/12/searching-for-manta-rays/">giant manta ray</a>. Some are threatened with extinction according to the IUCN, including great white sharks, basking sharks, whale sharks and oceanic white tip sharks.</p>
<figure class="align-center ">
<img alt="Basking shark and snorkellers" src="https://images.theconversation.com/files/350302/original/file-20200730-29-17ne8ug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350302/original/file-20200730-29-17ne8ug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350302/original/file-20200730-29-17ne8ug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350302/original/file-20200730-29-17ne8ug.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350302/original/file-20200730-29-17ne8ug.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350302/original/file-20200730-29-17ne8ug.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350302/original/file-20200730-29-17ne8ug.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">Basking sharks were once common in some coastal areas in New Zealand.</span>
<span class="attribution"><span class="source">Martin Prochazkacz/Shutterstock</span></span>
</figcaption>
</figure>
<p>Historically, basking sharks were caught as bycatch in New Zealand fisheries, and seen in their hundreds in some inshore areas. Sightings of these giant plankton-feeders suddenly <a href="https://www.stuff.co.nz/science/105112605/great-white-numbers-low-basking-sharks-rapidly-decline">dried up over a decade ago</a>. We don’t know why.</p>
<h2>Commercial shark fisheries</h2>
<p>Eleven chondrichthyan species are fished commercially in New Zealand under the <a href="https://www.sciencedirect.com/science/article/pii/S0308597X16303785">quota management system</a>. Commercial fisheries for school shark, rig and elephant fish <a href="https://www.publish.csiro.au/mf/MF97076">took off from the 1970s</a> and now catch around 8,000 tonnes per year in total. </p>
<p>Finning of sharks has been <a href="https://www.mpi.govt.nz/protection-and-response/sustainable-fisheries/managing-our-impact-on-marine-life/sharks/shark-finning-ban/">illegal throughout New Zealand</a> since 2014.</p>
<p>Most of New Zealand’s shark fisheries are <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.3053">considered sustainable</a>. But a sustainable fishery can mean sustained at low levels, and we must tread carefully. School shark was recently <a href="https://www.examiner.com.au/story/6829580/international-scientific-body-lists-school-shark-as-critically-endangered/">added to the critically endangered list</a> after the <a href="https://www.publish.csiro.au/mf/MF9590150">collapse of fisheries in Australia</a> and elsewhere, and there’s a lot we don’t know about the New Zealand population.</p>
<p>We do know sharks were <a href="https://www.publish.csiro.au/mf/MF97076">much more abundant</a> in pre-European times. In Tīkapa Moana (Hauraki Gulf), sharks have since declined <a href="https://fs.fish.govt.nz/Page.aspx?pk=113&dk=23958">by an estimated 86%</a>. An ongoing <a href="https://www.seachange.org.nz/">planning process</a> provides some hope for the ecosystems of the gulf.</p>
<h2>Protecting sharks</h2>
<p>Not surprisingly, the <a href="https://globalfinprint.org/about/index.html">global assessment</a> found a ban on shark fishing to be the most effective intervention to protect sharks. Several countries have recently established <a href="https://www.pewtrusts.org/en/research-and-analysis/fact-sheets/2016/03/shark-sanctuaries-around-the-world">large shark sanctuaries</a>, sometimes covering entire exclusive economic zones. </p>
<p>These countries tend to have ecotourism industries that provide economic incentives for protection — live sharks can be more valuable than dead ones. </p>
<p>Other effective interventions are restrictions on fishing gear, such as longlines and set nets. </p>
<p>Waters within 12 nautical miles of the Kermadec Islands have been protected by a <a href="https://www.doc.govt.nz/parks-and-recreation/places-to-go/northland/places/kermadec-islands/">marine reserve</a> since 1990. In 2015, the <a href="https://www.mfe.govt.nz/marine/kermadec-ocean-sanctuary/about-sanctuary">Kermadec Ocean Sanctuary</a> was announced but progress has <a href="https://www.rnz.co.nz/news/national/391563/govt-criticised-for-silence-on-kermadec-ocean-sanctuary">stalled</a>. The sanctuary would extend the boundaries to the exclusive economic zone, some 200 nautical miles offshore, and increase the protected area 83-fold. </p>
<p>A large population of Galapagos sharks, which prefer isolated islands surrounded by deep ocean, thrive around the Kermadec Islands but are found nowhere else in New Zealand. <a href="https://www.tvnz.co.nz/one-news/new-zealand/video-spell-binding-footage-shows-kermit-four-metre-long-great-white-shark-playing-camera-belonging-kiwi-researchers">Great white sharks also visit</a> en route to the tropics. Many other species are found only at the Kermadecs, including three sharks and a <a href="https://link.springer.com/article/10.1007/BF01314345">sex-changing giant limpet</a> as big as a saucer.</p>
<figure class="align-center ">
<img alt="Galapagos sharks" src="https://images.theconversation.com/files/350312/original/file-20200730-19-s8ozxz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350312/original/file-20200730-19-s8ozxz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350312/original/file-20200730-19-s8ozxz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350312/original/file-20200730-19-s8ozxz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350312/original/file-20200730-19-s8ozxz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350312/original/file-20200730-19-s8ozxz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350312/original/file-20200730-19-s8ozxz.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">Galapagos sharks were recorded around Raoul Island in the Kermadec archipelago.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/squid-team-finds-high-species-diversity-off-kermadec-islands-part-of-stalled-marine-reserve-proposal-110893">Squid team finds high species diversity off Kermadec Islands, part of stalled marine reserve proposal</a>
</strong>
</em>
</p>
<hr>
<h2>New technologies are revealing sharks’ secrets</h2>
<p>What makes the <a href="https://globalfinprint.org/about/index.html">Global FinPrint</a> project so valuable is that it uses a standard survey method, allowing data to be compared across the globe. The method uses a video camera pointed at a canister of bait. This contraption is put on the seafloor for an hour, then we watch the videos and count the sharks.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/SsudG7rNKpM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Grey reef, silver tip and hammerhead sharks circle a baited camera station set up near Walpole Island in the Southwest Pacific.</span></figcaption>
</figure>
<p>Baited cameras have been used in a few places in New Zealand but there are no systematic surveys at a national scale. We lack fundamental knowledge about the distribution and abundance of sharks in our coastal waters, and how they compare to the rest of the world.</p>
<p>Satellite tags are another technological boon for shark research. It is difficult to protect sharks without knowing where they go and what habitats they use. Electronic tags that transmit positional data via satellite can be attached to live sharks, <a href="https://www.nature.com/articles/s41598-020-66876-z">revealing the details of their movements</a>. <a href="https://niwa.co.nz/coasts-and-oceans/research-projects/white-sharks">Some have crossed oceans</a>.</p>
<p>Sharks have patrolled the seas for more than 400 million years. In a few decades, demand for shark meat and fins has <a href="https://conbio.onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2012.01835.x">reduced their numbers by around 90%</a>. </p>
<p>Sharks are generally more vulnerable to exploitation than other fishes. While a young bony fish can release tens of millions of eggs in a day, mature sharks lay a few eggs or give birth to a few live young. Females take many years to reach sexual maturity and, in some species, only reproduce once every two or three years.</p>
<p>These biological characteristics mean their populations are quick to collapse and slow to rebuild. They need careful management informed by science. It’s time New Zealand put more resources into understanding our oldest and most vulnerable fishes, and the far-flung subtropical waters in which they rule.</p><img src="https://counter.theconversation.com/content/143439/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Smith works for Massey University and has received funding from the Department of Conservation, the Ministry for Primary Industries, and the Australian Institute of Marine Science.</span></em></p>Historically, basking sharks were caught as bycatch in New Zealand fisheries and seen in their hundreds in some inshore areas. They have disappeared and we don’t know why.Adam Smith, Senior Lecturer in Statistics, Massey UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1354292020-04-06T20:06:21Z2020-04-06T20:06:21ZThe mushroom cloud’s silver lining: how the Cold War is helping the biggest fish in the sea<figure><img src="https://images.theconversation.com/files/325563/original/file-20200406-196131-1rarj4v.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5121%2C2683&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">United States Department of Defense/Wikimedia</span></span></figcaption></figure><p>It might surprise you to learn that nuclear bomb tests during the Cold War are now helping conserve whale sharks, the largest living fish. </p>
<p>Growing up to 18 metres – longer than the average bus – whale sharks live in all tropical oceans. In Australia, they are found off tropical coasts in the north, particularly in Western Australia.</p>
<p>Whale sharks face a number of threats. Globally they are <a href="https://www.iucnredlist.org/species/19488/2365291">listed as endangered</a>, and their numbers continue to decline.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/whale-shark-mugshots-reveal-teenage-males-hang-around-was-coast-68823">Whale shark mugshots reveal teenage males hang around WA's coast</a>
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</em>
</p>
<hr>
<p>Until recently, key information about the life history of whale sharks was missing, which prevented informed choices about how they were managed. In particular, scientists were not able to accurately assess their age and growth patterns.</p>
<p>Our research, <a href="https://www.frontiersin.org/articles/10.3389/fmars.2020.00188/abstract">published today</a> in Frontiers in Marine Science, changes that. We examined the skeleton of whale sharks, using carbon from Cold War atomic bomb testing as a “time stamp” to reveal their true age. The findings will help protect these beautiful animals into the future.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/325401/original/file-20200404-74279-lm9pjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325401/original/file-20200404-74279-lm9pjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325401/original/file-20200404-74279-lm9pjw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325401/original/file-20200404-74279-lm9pjw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325401/original/file-20200404-74279-lm9pjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325401/original/file-20200404-74279-lm9pjw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325401/original/file-20200404-74279-lm9pjw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Until now, it’s been difficult to assess the age of whale sharks.</span>
<span class="attribution"><span class="source">Wayne Osborn</span></span>
</figcaption>
</figure>
<h2>Gentle giants</h2>
<p>Whale sharks are placid “filter feeders”, which basically means they eat by opening their massive mouths and straining small fish and plankton that pass through the gills.</p>
<p>They are covered in a pattern of stripes and spots that provide camouflage as they bask at the surface. Whale sharks’ gentle nature and striking appearance has made them a drawcard for tourists who pay to snorkel or dive with the animals. </p>
<p>Whale shark ecotourism is big business. At Ningaloo Reef off Western Australia, the industry is worth an <a href="https://link.springer.com/article/10.1007/s11160-017-9486-x">estimated A$12.5 million per year</a>. </p>
<p>The industry is also valuable for small island nations such as the Maldives and developing countries including the Philippines and Indonesia. It has lifted thousands of villagers from poverty and provided an impetus for governments to protect whale sharks.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/poor-filipino-fishermen-are-making-millions-protecting-whale-sharks-122451">Poor Filipino fishermen are making millions protecting whale sharks</a>
</strong>
</em>
</p>
<hr>
<p>But all is not plain sailing for these animals. In some parts of the world they are <a href="https://www.abc.net.au/news/2014-02-05/an-hundreds-of-sharks-killed-annually-in-illegal-trade-in-china/5239568">hunted</a> for their fins, meat, oil and skin. The flesh resembles tofu when cooked, and is a popular menu item in parts of Asia, particularly China. </p>
<p>When shipping lanes are established near whale shark habitat, the animals are frequently struck by vessels and either die or suffer <a href="https://www.sciencedaily.com/releases/2020/01/200123152549.htm">propeller injuries</a> such as fin amputation. Their habit of <a href="https://theconversation.com/whale-sharks-swim-near-surface-to-keep-warm-10249">basking at the surface of the ocean</a> during the day puts whale sharks at particular risk of ship strike.</p>
<p>This combined with other threats – such as warming sea surface temperatures <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12343">due to climate change</a> – has created an uncertain future for these charismatic and valuable animals.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/325564/original/file-20200406-74216-111wnoc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325564/original/file-20200406-74216-111wnoc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325564/original/file-20200406-74216-111wnoc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325564/original/file-20200406-74216-111wnoc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325564/original/file-20200406-74216-111wnoc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325564/original/file-20200406-74216-111wnoc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325564/original/file-20200406-74216-111wnoc.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">A whale shark carcass on the shore of Teluk Betung beach in West Sumatra, Indonesia, last year. The animal is considered endangered.</span>
<span class="attribution"><span class="source">RAJO BATUAH/EPA</span></span>
</figcaption>
</figure>
<h2>The silver lining on the mushroom cloud</h2>
<p>Just how vulnerable whale shark populations are to these threats is not clear. Growth rates of fish species – or how many years they take to reach a certain size - determine their resilience, and how fast populations are likely to recover if severely damaged.</p>
<p>But determining the age of whale sharks has, to date, been very difficult. Their vertebrae feature distinct bands, similar to the rings of a tree trunk, which increase in number as the animal grows older. But the bands could not conclusively be used to determine age because some scientists believed a ring formed every year, but others suggested one formed every six months.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/325566/original/file-20200406-79380-rhoqqa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/325566/original/file-20200406-79380-rhoqqa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=537&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325566/original/file-20200406-79380-rhoqqa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=537&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325566/original/file-20200406-79380-rhoqqa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=537&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325566/original/file-20200406-79380-rhoqqa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=675&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325566/original/file-20200406-79380-rhoqqa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=675&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325566/original/file-20200406-79380-rhoqqa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=675&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cross section of a whale shark vertebra from Pakistan, showing 50 growth bands.</span>
<span class="attribution"><span class="source">Paul Fanning/ Pakistan node of the UN Food and Agricultural Organisation</span></span>
</figcaption>
</figure>
<p>To settle the debate, we turned to the radioactive legacy of the Cold War’s nuclear arms race - specifically, carbon-14.</p>
<p>Carbon-14 is a naturally occurring radioactive element. But in the 1950s and early 1960s, nuclear weapons tests by the US, Soviet Union, Great Britain, France and China released enormous amounts of carbon-14 into the air.</p>
<p>It travelled into the world’s oceans, and into every living organism on the planet – including the skeletons and shells of animals.</p>
<p>We analysed the vertebrae of two whale sharks collected many years ago in Taiwan and Pakistan. By counting back from the peak carbon-14 level, we concluded the rings were formed once per year. This meant that for the first time, the age and growth rate of a whale shark could accurately be determined; a 10-metre shark was 50 years old. </p>
<p>We know whale sharks can grow to almost twice the length of the animals we analysed, and have been estimated to live as long as <a href="https://link.springer.com/content/pdf/10.1023/A:1026564707027.pdf">100 years</a>. The results of our study makes that prediction now seem more likely. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/325565/original/file-20200406-74279-1876l9i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325565/original/file-20200406-74279-1876l9i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325565/original/file-20200406-74279-1876l9i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325565/original/file-20200406-74279-1876l9i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325565/original/file-20200406-74279-1876l9i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325565/original/file-20200406-74279-1876l9i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325565/original/file-20200406-74279-1876l9i.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">Whale sharks can live as long as 100 years.</span>
<span class="attribution"><span class="source">Wayne Osborn</span></span>
</figcaption>
</figure>
<h2>What does this mean for whale sharks?</h2>
<p>Slow-growing species with long lifespans are typically very susceptible to threats such as fishing. This is because it takes many years for animals to reach reproduction age, and the rate at which individuals are replaced is very slow. </p>
<p>Our study explains why fisheries targeting whale sharks almost immediately collapse: the species is not built to cope with the added pressures of human harvests.</p>
<p>Whale sharks populations take a very long time to recover from over-harvesting. Governments and management agencies must work together to ensure this iconic animal persists in tropical oceans - for both the future of the species, and the many communities whose livelihoods depend on whale shark ecotourism.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/whale-sharks-swim-near-surface-to-keep-warm-10249">Whale sharks swim near surface to keep warm</a>
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</p>
<hr>
<img src="https://counter.theconversation.com/content/135429/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Meekan receives funding from Santos Energy and the Save Our Seas Foundation.</span></em></p>The findings will help determine the age of whale sharks, protecting the endangered animals into the future.Mark Meekan, Senior Principal Research Scientist, Australian Institute of Marine ScienceLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/764502018-02-26T19:14:28Z2018-02-26T19:14:28ZFactFile: the facts on shark bites and shark numbers<figure><img src="https://images.theconversation.com/files/207813/original/file-20180226-140181-un3yf6.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6281%2C4045&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The CSIRO has provided new estimates of population sizes for White Sharks in Australian waters.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/great-white-shark-underwater-gansbaai-187721633">Fiona Ayerst/Shutterstock</a></span></figcaption></figure><p>Are there more sharks in Australian waters than there used to be, and are interactions between humans and shark increasing? Some Australian politicians <a href="https://thewest.com.au/news/sharks/esperance-shark-attack-fisheries-minister-dave-kelly-says-no-drum-lines-deployed-in-esperance-ng-b88449006z">have</a> <a href="https://www.perthnow.com.au/news/wa/frydenberg-says-blind-freddy-could-see-there-are-more-sharks-ng-2880626e17e34e8def6a7c983dfe6523">claimed</a> that to be the case.</p>
<p>Let’s look at the research.</p>
<p>The most reputable source for shark incident data in Australia is the <a href="https://taronga.org.au/conservation/conservation-science-research/australian-shark-attack-file">Australian Shark Attack file</a>, which is collated at Sydney’s Taronga Zoo. </p>
<p>The map below, created by The Conversation using data from the Australian Shark Attack File, shows incidents between sharks and humans in Australia between 1997 and 2017.</p>
<p>You can use the filter buttons in the map to explore the data by year, season, the type of injury, the type of shark involved, the type of incident – or a combination of all the filters. Press the ‘show all’ button to reset the search. </p>
<p><iframe id="tc-infographic-243" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/243/f87e27e72eb6545d5422e204b9894dedaad0f92f/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>The number of recorded encounters between sharks and humans in Australia increased modestly between 1997 and 2017, but the reason for this is unclear. Over those two decades, the Australian population <a href="http://www.abs.gov.au/ausstats/abs@.nsf/featurearticlesbytitle/ADF9B2B905D43653CA256FCE001101B5?OpenDocument">increased</a> <a href="http://www.abs.gov.au/ausstats/abs@.nsf/Latestproducts/3101.0Main%20Features1Jun%202017?opendocument&tabname=Summary&prodno=3101.0&issue=Jun%202017&num=&view=">by 33%</a>, but that alone doesn’t explain the increase in recorded shark encounters.</p>
<p>Correcting for the growth in human population in Australia, the data show that between 1997 and 2017: </p>
<ul>
<li>incidents resulting in injury increased by 1.59%</li>
<li>incidents without injury increased by 0.36%, and </li>
<li>fatalities increased by 0.07%. </li>
</ul>
<p>Encounters between humans and sharks are extremely variable over time, and difficult to predict. The increases in recorded incidents between 1997 and 2017 are relatively small, and may be explained by factors not related to shark populations – such as increases in the reporting of shark encounters, or increasing beach use.</p>
<p><iframe id="tc-infographic-159" class="tc-infographic" height="900" src="https://cdn.theconversation.com/infographics/159/62c30e6dedecffbbeb4e059c8ab0e573d756f61b/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>Are there more sharks off the Australian coast?</h2>
<p>White Sharks (formerly Great White Sharks) are recorded as being responsible for 28 of the 36 fatal shark encounters in Australian waters between 1997 and 2017, and are the primary target of shark mitigation strategies of the Western Australian, New South Wales and Queensland governments.</p>
<p>So, has there been an increase in the number of White Sharks in Australian waters? </p>
<p>Estimating population numbers in the marine environment is difficult, especially for long-lived migratory species like White Sharks.</p>
<p>However, there is no evidence that White Sharks numbers are on the rise, either in Western Australia or along the Eastern coast. Despite targeted conservation efforts, the available research show stable or slightly declining numbers in these populations.</p>
<p>There are <a href="http://era.daf.qld.gov.au/id/eprint/4509/">two distinct populations</a> of White Sharks off Australian coasts – one to the west, and another to the east of Bass Strait, which separates Tasmania from mainland Australia. The eastern population includes New Zealand White Sharks.</p>
<p><a href="https://www.nespmarine.edu.au/document/national-assessment-status-white-sharks">Recent work</a> by the CSIRO through the National Environmental Science Program’s Marine Biodiversity Hub using innovative DNA analysis has provided us with the most detailed and reliable estimates of population size we have for this species.</p>
<p>The CSIRO study shows there has been a slight decline in <em>adult</em> White Shark populations since the year 2000. </p>
<p>Current adult abundance for the eastern Australasian population is estimated at 750, with an uncertainty range of 470 to 1,030. The southern-western adult population is roughly double the size, estimated at 1,460, with an uncertainty range of 760 to 2,250.</p>
<p>Including the available information about juvenile White Sharks, estimates of total size for the <em>eastern</em> population in 2017 was 5,460, with an uncertainty range of 2,909 to 12,802.</p>
<p>It’s difficult to detect population trends with White Sharks because of the length of time it takes juveniles to reach maturity – <a href="https://www.nature.com/articles/s41598-018-20593-w">around 15 years</a>. As protection of White Sharks <a href="http://www.environment.gov.au/marine/marine-species/sharks/whiteshark">began in the late 1990s</a>, any changes in abundance would only be starting to appear in current populations.</p>
<h2>How else can we measure White Shark populations?</h2>
<p>The traditional way of measuring shark and fish populations is by examining catches in commercial fisheries over long time periods. By correcting for the level of fishing effort – which is done by looking at things like the number of nets, hooks and tows deployed by fishermen – scientists can assume that changes in the “catchability” of sharks is related to their abundance.</p>
<p>But due to the relative rarity of catches of White Sharks by fishing vessels, this approach is less reliable for this species than the more recent genetic studies conducted by the CSIRO and outlined above.</p>
<p>Western Australia has a detailed measure of White Shark numbers assessed by catch data. A <a href="http://www.fish.wa.gov.au/Documents/research_reports/frr277.pdf">report published by the Western Australian Department of Fisheries in 2016</a> attempted to model changes in the southern-western Australian White Shark population since the late 1930s. The authors outlined four different plausible scenarios, none of which suggested a continuous increase in the number of White Sharks.</p>
<p>In New South Wales, there has been a <a href="https://theconversation.com/shields-and-smart-buoys-new-technology-to-protect-sharks-and-people-48577">cluster of shark bites in recent years</a>. Data from the <a href="http://www.dpi.nsw.gov.au/fishing/sharks/management/shark-meshing-bather-protection-program">NSW Shark Meshing (Bather Protection) Program</a>, managed by the NSW Department of Primary Industries, show a recent increase in White Sharks caught in nets placed near ocean beaches.</p>
<p>But when it comes to thinking about shark populations, we should not assume that these two facts are related. It’s important to remember that just because two things may correlate, it doesn’t mean that one caused the other. </p>
<p>These patterns could mean that the animals are coming closer to shore, rather than a population increase (or decrease).</p>
<hr>
<p><iframe id="Zzcem" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/Zzcem/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<hr>
<h2>Shark and human interactions: what factors are at play?</h2>
<p>A <a href="http://www.sciencedirect.com/science/article/pii/S0964569116302058">2016 paper</a> examined six global shark bite “hotspots” – the United States, South Africa, Australia, Brazil, Reunion Island and the Bahamas – and concluded that when it comes to encounters between sharks and humans, there are a range of causes at play. </p>
<p>These include: </p>
<ul>
<li>rises in human population</li>
<li>habitat destruction/modification</li>
<li>changes in water quality</li>
<li>climate change</li>
<li>changing weather patterns, and </li>
<li>the distribution/abundance of prey.</li>
</ul>
<p>The authors also noted that shark encounters appear to happen in clusters. For example, 2009 saw a spike in shark encounters off the New South Wales coast. This coincided with an increase in beach attendance and beach rescues during what was an unusually warm summer for south-east Australia.</p>
<p>A <a href="http://www.publish.csiro.au/mf/MF10181">2011 paper</a> highlighted the popularity of water sports as a factor contributing to increased human-shark encounters. More people are taking part in water sports, and improvements in wetsuit technology mean that people are in the water for longer throughout the year.</p>
<p>However, there is limited information on the number of people who use Australian beaches, so this explanation needs to be further studied.</p>
<p>It’s vital that any strategies put in place to reduce the number of unprovoked encounters between humans and sharks in Australian waters are carefully considered, and based on the best available research.</p><img src="https://counter.theconversation.com/content/76450/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jane Williamson has received money from the Australian Research Council and from NSW Department of Primary Industries. She is Deputy Chair of the NSW Fisheries Scientific Committee</span></em></p><p class="fine-print"><em><span>Vincent Raoult has received funding from the NSW Department of Primary Industries and the University of Newcastle. </span></em></p>How many shark encounters have there been at your local beach? Explore our interactive map to see 20 years of incidents between humans and sharks in coastal waters around Australia.Jane Williamson, Associate Professor in Marine Ecology, Macquarie UniversityVincent Raoult, Postdoctoral fellow, University of NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/773992017-06-06T21:34:09Z2017-06-06T21:34:09ZCurious Kids: Do sharks sneeze?<figure><img src="https://images.theconversation.com/files/168515/original/file-20170509-20740-88e7iq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A shark's nose is chemosensory only, and it doesn’t join up to the back of the throat like ours does.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/leszekleszczynski/15447205451/in/photolist-px1Y1t-7AEZ2k-bMdCJ-Fsd6W-5HxWS-ek4Kv-21JtHU-cTV86-hPj18-WcigB-nbyoWA-GXtnA-9DGyME-6J8zm6-2eQkE-H28kr-9iiHZw-2VJce-rzEF8E-ek4KQ-4WjDVM-SXTa9-Wcig2-okzhU-aCvQE-6AKPRc-6SDamw-21u3i-21tZy-2gotK6-4K2qPB-ewqf-eMc7DJ-4K2qQp-JVfnt-7S3cGe-73boiZ-peS1wL-8auYco-a2QZa-hL3ps-6APYYG-73EmD9-gE6gjW-mGkjW-4Utjxk-2Bjt37-4mJ1cb-RY8Esq-orHiFR">Flickr/Leszek Leszczynski</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a new series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
<hr>
<blockquote>
<p><strong>Do sharks sneeze? – Desmond, aged 4, Perth.</strong></p>
</blockquote>
<p>When an animal sneezes, it’s their way of getting rid of annoying bits and pieces that have floated inside their nose and mouth.</p>
<p>While many animals, including <a href="https://www.youtube.com/watch?v=fyEajHy8Fzg">humans</a>, <a href="https://youtu.be/gtIz1u8g1F0">elephants</a>, <a href="https://youtu.be/93hq0YU3Gqk">pandas</a> and even <a href="https://www.youtube.com/watch?v=oGIlaSz9eHE">seals</a>, can sneeze, sharks unfortunately cannot. To be able to sneeze, an animal needs to move air (or water) from the lungs through its nose to the outside. </p>
<p>Sharks have two nostrils (called nares) below their snout that are used for smelling, but they don’t join up to the back of the throat like our nose does, so they can’t sneeze like we do. If something floats into their nares, they might try to shake it out.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=496&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=496&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171560/original/file-20170531-23681-1bkxgaq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=496&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Shark nostrils are called nares, but they do their breathing through their gills at the back of the mouth.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/lwpkommunikacio/14663970488/in/photolist-okNFxo-9NJybd-9NH9LR-8XQBnd-7kRvAK-ck8vcw-tHyeg6-9Nvxqd-CXXxV-9NAqQe-dugcMs-9NFVNX-9Nv8dj-9NEYMC-9NC9uz-4nmqPS-okP83k-9NvF6h-batHzF-6UGb1b-oC2r7v-p3RRp-p3QxL-adqDCb-dthtvX-aCPgav-9NDgMs-6Yz65f-5uJfYR-4nmqP5-4nhn2p-batHBa-batHyZ-4nhmUn-7co5Fo-rLXuC3-4nmqMm-6ADiza-amvWHZ-4RZRhc-4jmHMm-64FHLp-2kbyNw-5uNEcd-7bZkvH-5uJfcn-4KVtqJ-7co7Qb-559aXg-7cjgNR">Flickr/Lwp Kommunikáció</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Sharks breathe through the gills at the back of the mouth. Most of their “smelling” is done using a process called chemoreception, which allows sharks to sense tiny pieces of stuff, called molecules, hiding in the water as they pass through their nares.</p>
<p>Sharks can find and recognise these molecules – like parts of blood – that have been released from wounded animals or other prey, because their sense of smell is much better than ours. </p>
<p>Nares are loaded with powerful sensors. Once a shark has locked onto a smell, it can then work out where it came from by swimming towards it and moving its head slightly from side to side. It’s a bit like us following the smell of a freshly baked cake. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171559/original/file-20170531-23660-1sywmg3.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">It’s an exaggeration to say a shark can smell a single drop of blood in the ocean. But they might be able to smell tiny drops of blood in the water from up to five kilometres away.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/elevy/14730820387/in/photolist-orHiFR-86TtTf-7s62o-cfcR4-oJZUAK-FXJoL-7eLhsZ-49GjB8-cfWquS-551zjf-aJA7uv-6SQ6f3-mAQBh-78N7QT-b2dvkB-uAAvu-nNEH67-49GjJK-R6Pe-Vpfrz-kJsJbm-7bXmoE-49Lp8G-4AFffU-4KC2sV-CnoYi-5kStmp-9KKwc-jsEYG-eRDuu-8z3sa5-4VE1N3-bASq9s-bJatC-csBe15-5vUKUf-zzc7Y-4KnYic-j7dMVY-orHaNh-oGazeC-oHVAYR-map2Gv-orHgL8-QmN9g3-orGUyS-8wSLbJ-UPqA7d-5tUai4-orGNVX">Flickr/Elias Levy</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Legend has it that sharks can smell a single drop of blood in the ocean, but that’s an exaggeration. What they <em>can</em> do is detect blood at one part per million, which is similar to detecting tiny drops of blood in the water from up to five kilometres away!</p>
<p>While some have claimed to capture sightings of <a href="https://www.google.com.au/search?q=youtube+shark+nose&oq=youtube+shark+nose&aqs=chrome..69i57j0j69i60l3j0.1979j0j4&sourceid=chrome&ie=UTF-8#q=youtube+shark+sneeze">sharks sneezing on video</a>, it just isn’t physically possible.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ifM3H-oiR6k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">You might think this shark is sneezing, but trust me – it’s not.</span></figcaption>
</figure>
<p>The movement people confuse with sneezing is likely the animal’s attempt at getting rid of unwanted objects from their mouth or stomach area. </p>
<p>Sharks can actually make their stomach stick out of their mouth for brief moments to get rid of things they have eaten that they don’t like, such as tyres, licence plates, fish bones and fish hooks. This is called <a href="http://infinitespider.com/stomach-eversion-in-five-animals/">gastric eversion</a> and it’s a very cool trick.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/eoJdOOYfe4s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Gastric eversion is where a shark or other animal empties its stomach by making it stick out of their mouth.</span></figcaption>
</figure>
<p>Alternatively, a shark stretching its jaws, which they sometimes do after a meal, might be mistaken for a sneeze.</p>
<p>While sharks can’t sneeze like we do, they can smell and they have other great ways of getting rid of unwanted things from inside them.</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:</em></p>
<p><em>* Email your question to curiouskids@theconversation.edu.au
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?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"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><em>Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/77399/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jane Williamson 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>Sharks can’t sneeze like we do, but they can do other cool tricks – like making their stomach stick out of their mouth to get rid of unwanted stuff.Jane Williamson, Associate Professor in Marine Ecology, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/716332017-02-12T19:09:34Z2017-02-12T19:09:34ZHow drones can help fight the war on shark attacks<p>Following an <a href="https://taronga.org.au/conservation/conservation-science-research/australian-shark-attack-file">unprecedented series of shark attacks</a> off Australian beaches, the need to find practical solutions is intensifying. </p>
<p>Aerial drones could be an important tool for reducing risk of shark attacks on our beaches within the coming years. Here’s how it would work. Drones would fly autonomously over beaches continuously scanning for sharks with image recognition software. </p>
<p>If a shark is detected, real-time video will be instantly sent to beach authorities, such as lifeguards. If it is a dangerous shark, appropriate action can be taken to ensure public safety, such as sounding alarms and clearing people from the water.</p>
<p>Like other shark bite mitigation measures, this cannot completely eliminate the possibility of a shark attack. However, it could help to reduce the risk to an acceptable level for the majority of beach users.</p>
<p>Importantly, the drone-based approach to shark bite mitigation does not harm sharks or other marine wildlife, such as whales, dolphins, rays and sea turtles, unlike more controversial shark control measures such as mesh nets or baited drum lines.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iCcMT4r5Mik?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Surfer has a close encounter with a great white shark as seen by a drone.</span></figcaption>
</figure>
<h2>Testing drones</h2>
<p>As part of the NSW government’s A$16 million <a href="http://www.dpi.nsw.gov.au/fishing/sharks/shark-management">Shark Management Strategy</a>, researchers from the NSW Department of Primary Industries (NSW DPI) and Southern Cross University (SCU) have demonstrated that drones can reliably detect sharks off Australian beaches. </p>
<p>NSW DPI researchers have also compared the costs and benefits of marine wildlife sightings between drones and helicopters, as well as established environmental conditions suitable for drones to provide effective shark detection capabilities.</p>
<p>This summer, a team of SCU and DPI researchers completed an intensive <a href="https://www.youtube.com/watch?v=NnWhF3D6OxI&feature=youtu.be">drone trial</a> on five important beaches in NSW to verify that drones will work in the long term. As part of the trial, drones performed six 20-minute patrols each morning on each beach for every day of the school holidays. </p>
<p>Researchers monitoring drone footage spotted great white, bull, whaler, mako and hammerhead sharks off NSW beaches. They also saw many dolphins, sea turtles and less dangerous shark species, such as shovel-nosed sharks.</p>
<p>These trials included experiments comparing “people versus machines” by evaluating the utility of automated flight paths and shark recognition software. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/tlVNr81KZt8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drone captures a great white shark cruising the shallows of Northern NSW.</span></figcaption>
</figure>
<h2>Automating the drone-based approach</h2>
<p>The overall objective of this research is to develop a fully automated drone-based shark surveillance system in the near future.</p>
<p>We envisage that a team of aerial drones could run continuous shark detection missions during the hours when most people are on our beaches.</p>
<p>When required, each drone will automatically take off, patrol for sharks, land itself and charge up again, ready for the next mission. If a drone detects a shark, to can alert beach authorities.</p>
<p>Their response will vary depending on the species of shark detected and its location. This will be immediately apparent from the live video feed and location data they receive. As well as tracking sharks, the drones will also be fitted with sirens and lights to contribute to any emergency actions.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/aIEN3Af17kg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Great white shark off a beach in Northern NSW.</span></figcaption>
</figure>
<h2>Problems to solve</h2>
<p>There are still at least five major challenges to overcome before establishing a fully functional automated drone-based shark surveillance system. But these could be gradually overcome within the next few years.</p>
<p><strong>Civil aviation regulations</strong></p>
<p><a href="https://theconversation.com/got-a-drone-for-christmas-know-the-law-before-taking-to-the-skies-70341">Aviation regulations</a> restrict the use of fully automated drones in most airspace. We could overcome this problem by modifying the law or establishing restricted zones over beaches where drones can fly.</p>
<p><strong>Public safety concerns</strong></p>
<p>We need to minimise the risk of injury as a result of drone failure, by making sure their flight components are failsafe and having flight paths clear of beachgoers. We also need airspace safety systems to ensure that drones are grounded when emergency and other aircraft are in the vicinity.</p>
<p><strong>Public privacy concerns</strong></p>
<p>A drone-based shark surveillance system would require public acceptance. For this, beachgoers need to be aware of the sorts of data being collected by the drones, and to rest assured that this does not breach privacy legislation.</p>
<p><strong>Reliable hardware</strong></p>
<p>Although aerial drones can already automatically take off, fly routes, land and charge themselves, it is not clear how reliably this technology will stand up to the Australian beach environment. To be effective, we will need drones that can reliably function under heavy workloads in coastal conditions. Similarly, data transfer platforms also need to be fast and reliable.</p>
<p><strong>Purpose-designed software</strong></p>
<p>Image analysis software needs to be further developed to automatically detect sharks with a high level of accuracy. Customised software will also need to be developed to coordinate the missions of a team of drones and to ensure seamless video streaming to the portable wireless devices of beach authorities and users.</p>
<p>In terms of the hardware and software challenges, there are a number of research groups racing towards solutions with the goal of commercialising their products. Once an automated drone-based technology for shark bite mitigation is in place, it should be possible to solve issues regarding legislation, safety and privacy.</p>
<p>Given the current rate of technological development and the falling costs of commercially available drones, fully automated drones could be reducing the risk of shark attacks on Australian beaches within five years. However, for many nervous beachgoers, this may not be soon enough.</p><img src="https://counter.theconversation.com/content/71633/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brendan Kelaher receives funding from the NSW Department Primary Industries for two PhD students working on shark projects. </span></em></p><p class="fine-print"><em><span>Andrew Colefax receives project funding for his PhD from the NSW Department of Primary Industries (NSW DPI). He also receives additional work from the NSW DPI.</span></em></p><p class="fine-print"><em><span>Paul Butcher works for NSW Department of Primary Industries. He receives funding from the NSW and Commonwealth Governments. He is an Adjunct Associate Professor at Southern Cross University.</span></em></p><p class="fine-print"><em><span>Vic Peddemors receives funding from the NSW Government, the Australian Research Council and the Fisheries Research and Development Corporation (FRDC) on behalf of the Australian Government. </span></em></p><p class="fine-print"><em><span>Bob Creese 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>LIfeguards could potentially have a new ally in the fight to reduce shark incidents: drones that can spot when a shark swims nearby, and automatically alert authorities.Brendan Kelaher, Associate Professor of Marine Science and Management, Southern Cross UniversityAndrew Colefax, Phd candidate, Southern Cross UniversityBob Creese, Adjunct professor, Southern Cross UniversityPaul Butcher, Adjunct Professor, Southern Cross UniversityVic Peddemors, Shark Biology & Assessment, Sydney Institute of Marine ScienceLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/625672016-07-21T17:34:01Z2016-07-21T17:34:01ZI spent the past seven years counting white sharks – the findings are troubling<figure><img src="https://images.theconversation.com/files/131444/original/image-20160721-32639-9c7cem.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Monitoring white sharks more closely could help to ensure better conservation measures are put in place.</span> <span class="attribution"><span class="source">Dr Sara Andreotti (c) www.sharkdivingunlimited.com</span></span></figcaption></figure><p>Great white sharks are magnificent animals and it is truly an honour to work with them. They are top predators and probably the most studied shark in South African waters to date.</p>
<p>But one of the questions most often asked is: “how many of them are there?”
Due to the lack of empirical data, the answer to this question is mostly based on gut feeling, belief and <a href="https://vimeo.com/148095295">personal opinion</a>. Because of this, authorities often fail to implement conservation measures in time.</p>
<p>This is the reason why in 2009 world-renowned conservationist <a href="http://www.sharkdivingunlimited.com/about/the-team/">Michael (Mike) Rutzen</a>, and myself decided to do the obvious thing: to simply start counting them.</p>
<p>We undertook the data collection around the entire South African coastline. Considering that Dyer Island near Gansbaai – on the western coast of the country – is seen as the white shark’s capital of the <a href="https://www.yahoo.com/style/11-best-places-for-shark-cage-diving-123578950882.html">world</a>, we were expecting the population number to be quite high.</p>
<h2>Getting the numbers right</h2>
<p>Mike is a South African, well known from <a href="http://www.sharkdivingunlimited.com/media/international-documentaries/">international documentaries</a> like “The Sharkman”. In these documentaries, he <a href="https://www.youtube.com/watch?v=tnYvgyzy1b4">free-dives</a> with large species of sharks to dispel the myth that these beautiful creatures are human killing machines.</p>
<p>Relying on his 20 years of experience with great white sharks, building the study and identification protocol for the counting was relatively easy.</p>
<p>Once the protocol was <a href="http://onlinelibrary.wiley.com/doi/10.1111/jbi.12641/abstract">established,</a> we set sail for the most comprehensive project to date on South Africa’s white shark population. In and around Gansbaai we collected and, most importantly, analysed more than 5,000 photographs from which we could identify 426 individual white sharks by the unique notches of their <a href="http://link.springer.com/article/10.1007/s00227-011-1643-5">dorsal fins</a>.</p>
<p>We then performed a capture-mark-recapture analysis to ensure that we were not double-counting the same individuals. This works by building a re-sighting table, or a history-of-recapture matrix, in which the presence of each individual shark at a given time is recorded. To our surprise, we struggled to find new individuals to photograph once 400 white shark individuals were identified.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131440/original/image-20160721-32602-1vdpdb6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An integrated mark-recapture and genetic approach to estimate the population size of white sharks in South Africa.</span>
<span class="attribution"><span class="source">Andreotti et al Fig copia copia</span></span>
</figcaption>
</figure>
<p>This means that most of the white sharks visiting Gansbaai were already in the database. The results from this part of the study indicate with 95% confidence a population estimate of between 353 and 522 individuals. This is <a href="https://www.researchgate.net/publication/279435558_First_Estimates_of_Mortality_and_Population_Size_of_White_Sharks_on_the_South_African_Coast">52% less</a> than that estimated in previous <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0066035">mark-recapture studies</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131443/original/image-20160721-32633-95djmu.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">It was imperative to ensure that the white sharks being counted were representative of the entire white shark population along the South African coastline.</span>
<span class="attribution"><span class="source">Dr Sara Andreotti/ www.sharkdivingunlimited.com</span></span>
</figcaption>
</figure>
<h2>Another four years of sampling</h2>
<p>We needed to be sure that the white sharks we identified and counted in Gansbaai were representative of the entire white shark population along the South African coastline. So we set sail again and spent another four years sailing around the coastline collecting biopsy samples and photographs of dorsal fins. </p>
<p>The subsequent genetic analysis, performed under the supervision of Professor Conrad Matthee, from the Evolutionary Genomic Group at Stellenbosch University, proved that there is only one interbreeding population and that the same sharks are roaming the <a href="http://onlinelibrary.wiley.com/doi/10.1111/jbi.12641/abstract">entire coastline</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=562&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=562&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=562&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=706&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=706&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131473/original/image-20160721-32623-1mcwvj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=706&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) Dorsal fin photo identification of the same shark sampled at Algoa Bay and False Bay, about 800km away. (b) Example of the microsatellites score of two samples belonging to the same shark.</span>
<span class="attribution"><span class="source">Supplementary Material of Andreotti et al. 2016, Journal of Biogegraphy</span></span>
</figcaption>
</figure>
<p>Once we collected 303 genetic samples we took the analysis up another notch.
With the genetic analysis we were able to estimate the population size and double check the results of the photographic identification work. The biopsy samples came from 233 different white sharks. Analyses of 14 microsatellite markers revealed a contemporary effective population size of 333 individuals.</p>
<p>Genetic analysis is not the same as counting the sharks. With a genetic analysis we estimated the number of successful breeding individuals who generated the sampled population. The results can also be used to indicate the survival potential of a population. </p>
<p>It has been indicated that <a href="https://books.google.co.za/books?hl=en&lr=&id=F-XB8hqZ4s8C&oi=fnd&pg=PR13&dq=Frankham+R,+Ballou+JD,+Briscoe+DA+(2010)+Introduction+to+conservation+genetics,+2nd+edn.+Cambridge+University+Press,+Cambridge&ots=CKGhw07K3Q&sig=jDGAC5ibeCFc6YBdaMQVOI5kNnc&redir_esc=y#v=onepage&q&f=false">a minimum of 500 breeding individuals</a> are required to prevent inbreeding depression for a species.</p>
<p>The results of our study paint a very gloomy picture, with an estimated 333 breeding white sharks, based on samples collected around the entire coastline, for the South African population.</p>
<p>Even more troubling is the fact that the genetic estimate of 333 breeding white sharks does not reflect the current situation, as this is an estimate of how many sharks successfully bred one generation ago. When looking at the number of adults counted with the photo identification work, we can conclude that South Africa’s white sharks faced a rapid decline in the last generation. More concerning is that their numbers might already be too low to ensure their survival.</p>
<h2>Future action for conservation</h2>
<p>Our non-invasive study is the first of its kind. Not only did we sample known free-ranging white sharks, but we also built a database that links the genetic profile with the photographic identification of each individual shark. This combination of techniques provides a useful tool to double check the results of each technique. It results in a stronger and more reliable output.</p>
<p>In the light of these results we should consider more drastic actions to ensure the long-term survival of this ancient species. But as white sharks can’t be bred in captivity or relocated, we can only protect their environment and food resources if we want to conserve them. </p>
<p>In terms of legislation, making the regulation on their trade stricter could slow down the illegal trade in jaw trophies. Finally, in terms of immediate actions, we could halt the use of gill nets and baited hooks as shark-protection measures and hopefully move toward eco-friendly alternatives.</p>
<p>Our hope is that from now on white sharks will be monitored more closely and that better conservation measures will be put in place. We also hope that delicate arguments, like the estimate of a vulnerable population, will be based on acceptable scientific methods rather than the personal opinions of well-meaning individuals.</p><img src="https://counter.theconversation.com/content/62567/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>We thank Shark Diving Unlimited for the financial support, the vessels, logistical assistance, and the help of its staff. The Department of Environmental Affairs, South African National Parks and Cape Nature for providing permits to sample in the protected areas. Funded were provided by the Department of Botany and Zoology Postgraduate Bursary Scheme and lab work was funded through NRF incentive funding to Prof. Matthee.</span></em></p>South Africa’s white shark population faced a rapid decline in the last generation. More concerning is that their numbers might already be too low to ensure their survival.Sara Andreotti, Postdoctoral Researcher in management and conservation of white sharks, Stellenbosch UniversityLicensed as Creative Commons – attribution, no derivatives.