tag:theconversation.com,2011:/us/topics/sawfish-2490/articlesSawfish – The Conversation2023-11-02T19:12:25Ztag:theconversation.com,2011:article/2126902023-11-02T19:12:25Z2023-11-02T19:12:25ZTaming wild northern rivers could harm marine fisheries and threaten endangered sawfish<figure><img src="https://images.theconversation.com/files/556797/original/file-20231031-23-pl3bb0.JPG?ixlib=rb-1.1.0&rect=26%2C0%2C2198%2C1504&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Google Earth Image Landsat/Copernicus</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Australia’s tropical northern rivers still run wild and free. These relatively pristine areas have so far avoided extensive development. But this might not last. There are <a href="https://www.dcceew.gov.au/water/policy/national/northern-australia">ongoing scoping studies exploring irrigating agricultural land</a> using water from these rivers.</p>
<p>Our <a href="https://www.nature.com/articles/s41893-023-01238-x">new research</a> in the journal Nature Sustainability shows disturbing the delicate water balance upstream can have major consequences downstream, even hundreds of kilometres away.</p>
<p>Using our latest computer modelling, we found northern water resource development would have substantial effects on prawn, mud crab and barramundi fisheries in the Gulf of Carpentaria. These are valuable Australian marine fisheries which depend on healthy estuaries. Reducing river flows would also disturb mangrove and seagrass habitats and threaten the iconic endangered largetooth sawfish.</p>
<p>Freshwater flows to the sea play a crucial role, boosting the productivity of marine, estuarine and freshwater systems. These complex interactions must be carefully considered in the assessment of future development plans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic illustrating how altering river flow influences downstream estuarine and marine species and habitats" src="https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Changing the natural river flow regime has consequences for estuarine and marine species and fisheries.</span>
<span class="attribution"><span class="source">James Chen in Plaganyi et al (2023) Nature Sustainability</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/if-we-protect-mangroves-we-protect-our-fisheries-our-towns-and-ourselves-214390">If we protect mangroves, we protect our fisheries, our towns and ourselves</a>
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</p>
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<h2>Rivers are our lifeblood</h2>
<p>Worldwide, few wild running rivers remain. Their future is uncertain given <a href="https://turningthetide.watercommission.org/">growing demand for water</a>. </p>
<p>Climate change is putting extra pressure on rivers as temperatures rise, rainfall patterns shift and <a href="https://theconversation.com/marine-heatwaves-are-getting-hotter-lasting-longer-and-doing-more-damage-95637">extreme events</a> become more frequent. </p>
<p>Rivers are the lifeblood of ecosystems and communities. They connect land, estuaries and the sea. But assessments of river developments <a href="https://www.science.org/doi/epdf/10.1126/science.abj4017">often focus narrowly on local effects</a>. They ignore the fact downstream estuaries and marine systems depend on freshwater flows. Few studies have calculated the costs of upstream catchment developments to downstream estuarine and marine ecosystems and fisheries.</p>
<p>We must avoid the <a href="https://theconversation.com/damming-northern-australia-we-need-to-learn-hard-lessons-from-the-south-53885">mistakes made in southern Australia</a> where <a href="https://theconversation.com/excessive-water-extractions-not-climate-change-are-most-to-blame-for-the-darling-river-drying-192621">too much water has been taken out of the system</a> for growing crops. That means carefully evaluating the design of dams or irrigation schemes, considering when, where and how much water should be taken – and the likely trade-offs. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo showing many common banana prawns on a trawler. This is one of several species caught by the Northern Prawn Fishery" src="https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.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">Yields of common banana prawn vary depending on river flows from multiple catchments.</span>
<span class="attribution"><span class="source">NPF Industry Pty Ltd, Australian Council of Prawn Fisheries Ltd, Austral Fisheries and Raptis Seafoods</span></span>
</figcaption>
</figure>
<h2>Why should we care about northern rivers?</h2>
<p>Australia’s remote northern rivers are one of the last strongholds for endangered species such as the <a href="https://theconversation.com/australian-endangered-species-largetooth-sawfish-24558">largetooth sawfish</a>. These iconic species are born in estuaries before spending their first few years of life upstream in freshwater rivers. </p>
<p>Flows from these rivers also sustain extensive mangrove forests and seagrass beds. Periodic floods <a href="https://www.abc.net.au/news/2020-10-30/barramundi-banana-prawns-could-be-threatened-gulf-of-carpentaria/12828280">boost the food supply</a> for many prized marine fisheries such as prawns, barramundi and <a href="https://tinyurl.com/2haudz3t">mud crabs</a>.</p>
<p>The rivers also have <a href="https://indigenousknowledge.unimelb.edu.au/curriculum/resources/indigenous-voices-in-water">cultural significance</a> for Aboriginal people and represent a valuable resource, providing food and supporting livelihoods. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of an endangered largetooth sawfish in shallow water" src="https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.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">Endangered largetooth sawfish are sensitive to changes in river flows.</span>
<span class="attribution"><span class="source">Rich Pillans/CSIRO</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/an-el-nino-hit-this-banana-prawn-fishery-hard-heres-what-we-can-learn-from-their-experience-139852">An El Niño hit this banana prawn fishery hard. Here’s what we can learn from their experience</a>
</strong>
</em>
</p>
<hr>
<h2>Using modelling to connect rivers, estuaries and oceans</h2>
<p>We coupled CSIRO’s sophisticated <a href="https://www.csiro.au/en/showcase/nawra">river models</a> with our <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1467-2979.2012.00488.x">specially tailored ecosystem models</a> to represent how altering river flows may influence the downstream ecology and fishery yields. </p>
<p>We used catch data from fisheries to analyse how past natural changes in flow influenced catch rates. This was combined with extensive previous research on the biology and ecology of each species to model the dynamics of catchment-to-coast systems. We were particularly interested in the natural life cycles of fish and crustaceans in our unique northern wet-dry tropical rivers and estuaries. We then simulated multiple water resource development scenarios to assess and compare various impacts and ways to reduce them. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two column charts showing risk to key populations and fisheries in the Gulf of Carpentaria from changes in freshwater flows." src="https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=562&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=562&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=562&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=707&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=707&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=707&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We quantified risk to key populations and fisheries in the Gulf of Carpentaria from changes in freshwater flows due to various hypothetical water resource developments (WRD).</span>
<span class="attribution"><span class="source">Plagányi et al. (2023) Nature Sustainability</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>For <a href="https://tinyurl.com/2haudz3t">mud crabs, we linked river flow</a> and other climate drivers to their life cycle and were able to show how past changes in flow could explain the past variation in crab catch, particularly for rivers in which flow was seasonally variable. We could then use this model to predict how crab catch and abundance might change in the future, depending on how much water is removed from rivers and the method of removal.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial image of an estuary feeding into the Gulf of Carpentaria" src="https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.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">Rivers connect land, estuaries and the sea. Large estuaries feed into the Gulf of Carpentaria.</span>
<span class="attribution"><span class="source">Queensland Department of Agriculture and Fisheries</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-industry-lines-up-to-take-water-from-a-wild-top-end-river-trees-tell-the-story-of-a-much-drier-past-177221">As industry lines up to take water from a wild Top End river, trees tell the story of a much drier past</a>
</strong>
</em>
</p>
<hr>
<h2>Integrated management from catchment to coast</h2>
<p>Our research shows freshwater flows to the sea are crucial for environmentally and economically important species. Any plan to dam or extract freshwater from Australia’s last wild rivers should account for these effects.</p>
<p>Coupling scientific knowledge about marine and freshwater ecosystems with catchment development will improve infrastructure planning and flow management.</p>
<p>This is vital on a dry continent already <a href="https://theconversation.com/extreme-weather-caused-by-climate-change-has-damaged-45-of-australias-coastal-habitat-120671">challenged by climate change</a>. Every drop counts.</p>
<p><em>The authors wish to acknowledge Annie Jarrett, Chief Executive Officer of NPF Industry Pty Ltd, which represents Northern Prawn Fishery operators, for her contribution to the research.</em></p><img src="https://counter.theconversation.com/content/212690/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Éva Plagányi acknowledges Annie Jarrett, Chief Executive Officer of NPF Industry Pty Ltd, which represents Northern Prawn Fishery operators, for her contribution to the research.
Éva works for CSIRO and receives research funding from several sources, including the Fisheries Research and Development Corporation (FRDC) and the Australian Fisheries Management Authority (AFMA).
2018-079 Ecological modelling of the impacts of water development in the Gulf of Carpentaria with particular reference to impacts on the NPF was supported by funding from the Fisheries Research and Development Corporation on behalf of the Australian Government</span></em></p><p class="fine-print"><em><span>Laura Blamey works for CSIRO, which receives research funding from several source, including the Fisheries Research and Development Corporation (FRDC) and the Australian Fisheries Management Authority (AFMA).</span></em></p><p class="fine-print"><em><span>Michele Burford works for the Australian Rivers Institute, Griffith University and receives funding from several sources, including the National Environmental Science Program (NESP).</span></em></p><p class="fine-print"><em><span>Robert Kenyon works CSIRO, an organisation that receives research funding from several sources, including the Fisheries Research and Development Corporation (FRDC) and the Australian Fisheries Management Authority (AFMA).</span></em></p>Any plan to dam or extract water from some of Australia’s last wild rivers must carefully consider the consequences. Prawn, mud crab and barramundi fisheries could suffer in the Gulf of Carpentaria.Éva Plagányi, Senior Principal Research Scientist, CSIROLaura Blamey, Senior Research Scientist, CSIROMichele Burford, Professor - Australian Rivers Institute, and Dean - Research Infrastructure, Griffith UniversityRobert Kenyon, Marine Ecologist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1340672020-03-18T18:05:42Z2020-03-18T18:05:42ZWe’ve just discovered two new shark species – but they may already be threatened by fishing<figure><img src="https://images.theconversation.com/files/321329/original/file-20200318-1942-12qjqmq.jpg?ixlib=rb-1.1.0&rect=37%2C29%2C4955%2C1684&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">One of the newly discovered sixgilled sawshark species (_Pliotrema kajae_).</span> <span class="attribution"><span class="source">Simon Weigmann</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Finding a species that’s entirely new to science is always exciting, and so we were delighted to be a part of <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228791">the discovery of two new sixgill sawsharks</a> (called <em>Pliotrema kajae</em> and <em>Pliotrema annae</em>) off the coast of East Africa.</p>
<p>We know very little about sawsharks. Until now, only one sixgill species (<em>Pliotrema warreni</em>) was recognised. But we know sawsharks are carnivores, living on a diet of fish, crustaceans and squid. They use their serrated snouts to kill their prey and, with quick side-to-side slashes, break them up into bite-sized chunks. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321317/original/file-20200318-37382-1kvg3zk.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The serrated snout of a sixgill sawshark (<em>Pliotrema annae</em>).</span>
<span class="attribution"><span class="source">Ellen Barrowclift-Mahon/Marine MEGAfauna Lab/Newcastle University.</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Sawsharks look similar to sawfish (which are actually rays), but they are much smaller. Sawsharks grow to around 1.5 metres in length, compared to 7 metres for a sawfish and they also have barbels (fish “whiskers”), which sawfish lack. Sawsharks have gills on the side of their heads, whereas sawfish have them on the underside of their bodies. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321354/original/file-20200318-1953-1i2ndk3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A sixgill sawshark (<em>Pliotrema annae</em>) turned on its side, showing gills and barbels.</span>
<span class="attribution"><span class="source">Ellen Barrowclift-Mahon</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Together with our colleagues, we discovered these two new sawsharks while researching small-scale fisheries that were operating off the coasts of Madagascar and Zanzibar. While the discovery of these extraordinary and interesting sharks is a wonder in itself, it also highlights how much is still unknown about biodiversity in coastal waters around the world, and how vulnerable it may be to poorly monitored and managed fisheries.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/321322/original/file-20200318-37441-1xec9fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321322/original/file-20200318-37441-1xec9fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=549&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321322/original/file-20200318-37441-1xec9fr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=549&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321322/original/file-20200318-37441-1xec9fr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=549&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321322/original/file-20200318-37441-1xec9fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=690&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321322/original/file-20200318-37441-1xec9fr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=690&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321322/original/file-20200318-37441-1xec9fr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=690&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The three known species of sixgill sawshark. The two new species flank the original known species. From left to right: <em>Pliotrema kajae</em>, <em>Pliotrema warreni</em> (juvenile female) and <em>Pliotrema annae</em> (presumed adult female).</span>
<span class="attribution"><span class="source">Simon Weigmann</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Fishing in the dark</h2>
<p>Despite what their name might suggest, small-scale fisheries employ around 95% of the world’s fishers and are an <a href="https://theconversation.com/local-communities-play-outsized-but-overlooked-role-in-global-fisheries-123143">incredibly important source of food and money</a>, particularly in tropical developing countries. These fisheries usually operate close to the coast in some of the world’s most important biodiversity hotspots, such as coral reefs, mangrove forests and seagrass beds. </p>
<p>For most small-scale fisheries, there is very little information available about their fishing effort – that is, how many fishers there are, and where, when and how they fish, as well as exactly what they catch. Without this, it’s very difficult for governments to develop management programmes that can ensure sustainable fishing and protect the ecosystems and livelihoods of the fishers and the communities that depend on them.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/321316/original/file-20200318-37397-yjxu6s.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321316/original/file-20200318-37397-yjxu6s.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321316/original/file-20200318-37397-yjxu6s.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321316/original/file-20200318-37397-yjxu6s.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321316/original/file-20200318-37397-yjxu6s.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321316/original/file-20200318-37397-yjxu6s.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321316/original/file-20200318-37397-yjxu6s.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">Small-scale fishers of Zanzibar attending their driftnets.</span>
<span class="attribution"><span class="source">Per Berggren/Marine MEGAfauna Lab/Newcastle University</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>While the small-scale fisheries of East Africa and the nearby islands are not well documented, we do know that there are at least <a href="https://doi.org/10.1007/s11160-017-9494-x">half a million small-scale fishers using upwards of 150,000 boats</a>. That’s a lot of fishing. While each fisher and boat may not catch that many fish each day, with so many operating, it really starts to add up. Many use nets – either driftnets floating at the surface or gillnets, which are anchored close to the sea floor. Both are cheap but not very selective with what they catch. Some use longlines, which are effective at catching big fish, including sharks and rays.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sharks-one-in-four-habitats-in-remote-open-ocean-threatened-by-longline-fishing-120849">Sharks: one in four habitats in remote open ocean threatened by longline fishing</a>
</strong>
</em>
</p>
<hr>
<p>In 2019, our team reported that catch records <a href="https://doi.org/10.1016/j.biocon.2018.12.024">were massively underreporting the number of sharks and rays caught</a> in East Africa and the nearby islands. With the discovery of two new species here – a global hotspot for shark and ray biodiversity – the need to properly assess the impact of small-scale fisheries on marine life is even more urgent.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=207&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=207&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=207&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=260&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=260&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321319/original/file-20200318-37401-19jg3xr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=260&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Pliotrema kajae</em>, as it might look swimming in the subtropical waters of the western Indian Ocean.</span>
<span class="attribution"><span class="source">Simon Weigmann</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>How many other unidentified sharks and other species are commonly caught in these fisheries? There is a real risk of species going extinct before they’re even discovered. </p>
<p>Efforts to monitor and manage fisheries in this region, and globally, must be expanded to prevent biodiversity loss and to develop sustainable fisheries. There are simple methods available that can work on small boats where monitoring is currently absent, including using cameras to document what’s caught. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/321356/original/file-20200318-1972-n0x8np.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/321356/original/file-20200318-1972-n0x8np.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/321356/original/file-20200318-1972-n0x8np.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/321356/original/file-20200318-1972-n0x8np.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/321356/original/file-20200318-1972-n0x8np.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/321356/original/file-20200318-1972-n0x8np.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/321356/original/file-20200318-1972-n0x8np.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 selection of landed fish – including sharks, tuna and swordfish.</span>
<span class="attribution"><span class="source">Per Berggren</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The discovery of two new sixgill sawsharks also demonstrates the value of scientists working with local communities. Without the participation of fishers we may never have found these animals. From simple assessments all the way through to developing methods to alter catches and manage fisheries, it’s our goal to make fisheries sustainable and preserve the long-term future of species like these sawsharks, the ecosystems they live in and the communities that rely on them for generations to come.</p><img src="https://counter.theconversation.com/content/134067/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Per Berggren receives funding from the Western Indian Ocean Marine Science Association (Grant Number MASMA/CP/2014/01).</span></em></p><p class="fine-print"><em><span>Andrew Temple receives funding from the Western Indian Ocean Marine Science Association (Grant Number MASMA/CP/2014/01).</span></em></p>Scientists thought there was only one sixgill sawshark species – until now.Per Berggren, Marine MEGAfauna Lab, Newcastle UniversityAndrew Temple, Postdoctoral Research Associate in Marine Biology, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1031182018-09-17T12:51:56Z2018-09-17T12:51:56ZEducation can help protect sawfishes in Mozambique and Madagascar<figure><img src="https://images.theconversation.com/files/236167/original/file-20180913-177935-4778rw.JPG?ixlib=rb-1.1.0&rect=2%2C232%2C1595%2C1058&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fisherman holds up the saw of a sawfish caught in Madagascar. The species is dwindling along the coasts of Madagascar and Mozambique. </span> <span class="attribution"><span class="source">Ruth H. Leeney</span></span></figcaption></figure><p>Of all sharks and rays worldwide, sawfishes – related to stingrays and manta rays – are considered to be the <a href="https://elifesciences.org/articles/00590">family at greatest risk of extinction</a>. The long, toothed saw – which gives them their unique appearance – also makes them extremely vulnerable to entanglement in fishing nets. Their numbers <a href="http://www.iucnssg.org/conservation-strategies-sawfish.html">have fallen</a> because they are caught accidentally in industrial fishing nets. In addition to that, they are targeted by some fishermen because their fins can fetch high prices.</p>
<p>There are five species of sawfish globally. Two can reach around seven metres in total length (including the saw), making them the third largest members of the shark and ray family. </p>
<p>Sawfishes were formerly common along both the west and east coasts of Africa. Until a few years ago there was no knowledge of whether they still inhabited these waters, or if populations had plummeted as they have done elsewhere. </p>
<p>I set about addressing this gap six years ago. Since then, I have interviewed more than 500 fishers in six different African countries. I collected information on when and where people last caught sawfishes, how they used them and what their local value was. My research showed that sawfishes are now locally extinct from many parts of West Africa, but are still encountered – at least occasionally – by fishers in Madagascar and northern <a href="https://peerj.com/articles/2950/">Mozambique</a>. </p>
<p>Working in fishing communities and engaging in the lives of fishers has provided me with some insights into how sawfishes can best be protected in countries like Madagascar, as well as an understanding of the approaches that won’t work. </p>
<p>In the two developed countries where sizeable sawfish populations still exist – Australia and the US – an important step in preventing further declines of these endangered species is to declare them protected under national law and to prohibit activities that threaten them. So catching and killing of sawfishes is banned. </p>
<p>This is an effective approach in countries with the capacity and funding to enforce such laws. But in developing countries, a different approach is needed - a “bottom-up” approach in which communities take the lead. And for that to happen, scientists need to convey the implications of their research to the people who rely directly on the natural resources around them, in relevant, easy-to-digest ways.</p>
<h2>The challenge</h2>
<p>Sawfishes are not legally protected in most African nations. And even if they were, legislation is rarely an effective approach in countries with little or no capacity to enforce species protection laws. </p>
<p>In addition, fishers who catch sawfishes value them as sources of income (through the sale of their fins, meat, and occasionally other parts) and food. Artisanal fishers along the coasts of Madagascar and Mozambique are some of the <a href="http://hdr.undp.org/en/composite/HDI">poorest</a> communities in these countries; they often live in remote rural areas and have few alternatives to fishing as a way to make a living.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/236458/original/file-20180914-177962-qhbq2a.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A juvenile largetooth sawfish, Australia.</span>
<span class="attribution"><span class="source">David Morgan</span></span>
</figcaption>
</figure>
<p>Unless fishers are provided with livelihood alternatives, any efforts to prevent sawfish mortality could be considered to compromise their immediate wellbeing. Fishers are unlikely to sign up to an approach which will mean more hardship for them.</p>
<h2>What can be done</h2>
<p>We need to reduce the number of sawfishes being caught in fisheries, and ensure that their habitats, especially coastal waters and mangroves, are protected. These two steps would have far-reaching and long-term benefits. </p>
<p>But in my view, the only way to achieve these goals is by encouraging communities to become caretakers of the natural resources they rely on for their own survival. And to achieve this, they first need to understand why these goals should matter to them. </p>
<p>The right educational tools can be used to explain that freshwater and marine ecosystems, fished responsibly, provide food and saleable goods, while mangroves protect coastal communities from <a href="https://www.int-res.com/abstracts/meps/v343/p101-105/">storm surge</a> and erosion. The communities themselves can then understand the trade-off between short-term, personal gain and longer-term, communal value, and can choose which path they wish to take. </p>
<p>My insight from working in fishing communities is that as a scientist, I have a duty to explain my findings, their implications and encourage communities to engage in developing strategies to address conservation issues. This benefits the communities as well as the species and habitats that need protection.</p>
<p>To this end I developed a short educational <a href="https://www.youtube.com/watch?v=jZ9RXxGikwc&t=12s">film</a> and a story <a href="https://issuu.com/saveourseas/docs/the_king_of_fishes_-_english_editio">book</a>. These both aim to convey the importance of sharks and sawfishes as part of healthy marine and freshwater ecosystems. They also point out the many ways in which communities stand to benefit from the sustainable use of sawfishes and other aquatic resources. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/236457/original/file-20180914-177941-ormy53.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Children in Madagascar reading ‘The King of the Fishes’.</span>
<span class="attribution"><span class="source">Ruth H. Leeney</span></span>
</figcaption>
</figure>
<p>The film was made in multiple languages for both Mozambican and Malagasy audiences to ensure it could reach the widest possible audience. These resources have also given audiences beyond Africa insight into the lives of fisherfolk and the specific challenges facing sawfish conservation in these places.</p>
<p>The experience has taught me that we may be missing opportunities to use stories built around our work, to inspire interest and change where it is most needed: at community level. Armed with the right knowledge and understanding of why protecting mangroves, coastal waters and their inhabitants is important, communities can be the caretakers of these natural resources, both for their own benefit and for the planet’s.</p><img src="https://counter.theconversation.com/content/103118/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ruth H. Leeney's research in Mozambique and the development of educational materials for Mozambique and Madagascar was funded by NOAA Fisheries grant NA15NMF4690193. She was funded by the New England Aquarium Marine Conservation Action Fund, the Rufford Foundation, the Swiss Shark Foundation and the Save Our Seas Foundation. </span></em></p>Africa’s remaining sawfishes are found along the coasts of Madagascar and Mozambique. But they are under threat.Ruth H. Leeney, Scientific Associate, Department of Life Sciences, Natural History MuseumLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/277432014-07-08T04:44:28Z2014-07-08T04:44:28ZPlundered for their unique body parts, sawfish are on the brink<figure><img src="https://images.theconversation.com/files/52041/original/csbcw3tw-1403590592.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The world's five species of sawfish are the most threatened fishes in the world.</span> <span class="attribution"><span class="source">David Wackenfelt</span></span></figcaption></figure><p>Sawfish are the most endangered group of marine fish in the world, largely thanks to overfishing and habitat loss. Formerly abundant, they have disappeared from many countries’ waters, and in many others they are scarcely holding on.</p>
<p>To put it bluntly, sawfish have been devastated. But we could reverse the trend. Recently the International Union for Conservation of Nature’s Shark Specialist Group released the first <a href="http://www.dulvy.com/global-sawfish-conservation-strategy.html">Global Sawfish Conservation Strategy</a>. It won’t be easy, but they are steps we need to take if we are to save the world’s threatened sawfish.</p>
<h2>Tall tales</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/52037/original/c32hb9fx-1403590209.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A “smalltooth” sawfish from the Everglades, Florida.</span>
<span class="attribution"><span class="source">Colin Simpfendorfer</span></span>
</figcaption>
</figure>
<p>There are five species of sawfish — all large, iconic, tropical and subtropical fish closely related to <a href="https://theconversation.com/sharks-and-rays-threatened-worldwide-overfishing-to-blame-22186">sharks</a>. </p>
<p>These are the world’s largest rays, with one species growing to reach 7 metres in length. Even the smallest species, the Dwarf, reaches over 3 metres.</p>
<p>They are a charismatic group of fish, with various legends attached (all can be found in the <a href="http://www.dulvy.com/uploads/2/1/0/4/21048414/sawfish_singlepages_hr.pdf">sawfish strategy</a>). Sawfish body parts have been hung over doorways to keep ghosts out. Muslim teachers rode on their backs performing miracles. </p>
<p>In the 16<sup>th</sup> century one saved a vessel by plugging a hole in its hull. Dozens of the animals are interred beneath the Aztec Great Temple of Mexico City. And sawfish have been used to make cowboy boots, fence posts, weapons, and to cure diarrhoea.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=316&fit=crop&dpr=1 600w, https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=316&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=316&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=398&fit=crop&dpr=1 754w, https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=398&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/52038/original/cvm56vwp-1403590215.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=398&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sawfishes are the world’s largest rays.</span>
<span class="attribution"><span class="source">Sawdeep Shenoy</span></span>
</figcaption>
</figure>
<h2>History of decline</h2>
<p>All five species are now classed as Endangered or Critically Endangered. Of the 92 countries where they used to be found, 43 countries have lost at least one species, and sawfish are completely extinct from 20 countries. </p>
<p>While they have declined in area, there is hope that sawfish will persist in more remote regions such as <a href="https://theconversation.com/australian-endangered-species-largetooth-sawfish-24558">Northern Australia</a>, which is home to relatively healthy populations of four species. </p>
<p>Like many threatened marine animals we can point to overexploitation and habitat loss. The long toothed rostrum of sawfishes is easily entangled in nets. </p>
<p>Their fins, rostra (the sawfish’s “saw”), meat and other body parts can fetch a fair price, in fact their fins are amongst the most preferred in the Asian shark fin soup market, and can fetch up to US$4,000 a set. These are arguably some of the most valuable marine products in trade. This has helped drive sawfish retention when they have been caught as bycatch in fisheries. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/52039/original/vny8g42w-1403590485.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Overfishing - including de-sawing - is the major threat to sawfish.</span>
<span class="attribution"><span class="source">David Morgan</span></span>
</figcaption>
</figure>
<p>They live in shallow, inshore, coastal and riverine waters, and these habitats overlap with intense fisheries and habitat modification. </p>
<p>In many tropical parts of the world these activities are unregulated and unmanaged. Throw in their biological traits – like many sharks and rays, sawfishes have low productivity – and they do not have the capacity to sustain high levels of exploitation or to recover from that without serious conservation action.</p>
<h2>Five steps to sawfish recovery</h2>
<p>If we want to recover sawfish populations, then we are going to have to get serious. </p>
<p>Like many conservation programs, it will require a combination of actions. But many of these actions are the kinds of things that would improve fisheries sustainability and the conservation of a wide range of large coastal wildlife such as sawfish anyway. Minimising the threats of habitat loss and overfishing is the key.</p>
<p>Here are five steps we should take to protect sawfish. </p>
<p>First, international conservation agreements. With sawfish ranging across nearly 100 countries, there will need to be action at international and regional levels, not only at national levels. The <a href="http://www.cites.org/eng/cop/16/prop/E-CoP16-Prop-45.pdf">listing of sawfishes</a> on the Convention on International Trade in Endangered Species, following Australia’s proposal, is a great step. Protection on other international conventions, such as the <a href="http://www.cms.int/">Convention on Migratory Species</a>, is an obvious next step. </p>
<p>Second, legal protection of sawfishes in key range states. Sawfish are currently only protected in 16 countries. Sawfish need protection in a number of priority countries including Papua New Guinea, Pakistan, Tanzania, Guinea, Venezuela and Cuba. These are countries where sawfish are barely holding on, or may persist in remote areas.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/52040/original/3hdx8mwq-1403590541.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">Educating fishers about sawfish in Derby, Western Australia.</span>
<span class="attribution"><span class="source">Jeff Whitty</span></span>
</figcaption>
</figure>
<p>Third, community engagement and outreach. We hear this a lot in conservation, but only by engaging with local communities on the ground can effective change be made. We need to develop a community toolbox to raise awareness and help collect data. The toolbox might include: identification materials, safe handling and release guidelines, data collection guidance, and ways to reduce bycatch. There is great work already happening in places like West Africa but more is needed.</p>
<p>Fourth, enforcement. Sawfish countries will need to strictly enforce fisheries management and international and national conservation regulations. Enforcement starts with good training to provide enforcement and customs officers with the skills they will require which includes species identification.</p>
<p>Finally, fundraising. This may indeed be one of the greatest challenges. But the development of a network of nearly 150 sawfish experts has made great headway in raising sufficient awareness and local funding.</p>
<p>Sawfish can be saved. The progress made in Australia and the USA shows that sawfish populations can be protected and populations may even be recovered. </p>
<p>Through these simple and proven actions we have the power to save these most imperilled and iconic marine fishes.</p><img src="https://counter.theconversation.com/content/27743/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Kyne receives funding from the Marine Biodiversity Hub and the Northern Australia Hub, collaborative partnerships supported through funding from the Australian Government’s National Environmental Research Program (NERP). He is Regional Vice-Chair of the Australia and Oceania IUCN Shark Specialist Group.</span></em></p>Sawfish are the most endangered group of marine fish in the world, largely thanks to overfishing and habitat loss. Formerly abundant, they have disappeared from many countries’ waters, and in many others…Peter Kyne, Senior Research Fellow in conservation biology, Charles Darwin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/245582014-04-17T21:49:35Z2014-04-17T21:49:35ZAustralian endangered species: Largetooth Sawfish<figure><img src="https://images.theconversation.com/files/44221/original/pn7hdnwb-1395180360.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Largetooth Sawfish is one of the world's largest fishes, growing to more than 6 metres. </span> <span class="attribution"><span class="source">Miguel Clavero</span></span></figcaption></figure><p>Sharks and rays are some of the <a href="https://theconversation.com/sharks-and-rays-threatened-worldwide-overfishing-to-blame-22186">world’s most threatened animals</a>, with a quarter of all species at risk of extinction. Among the sharks and rays, sawfish are some of the most threatened, with all five species listed as <a href="http://www.iucnredlist.org/">Critically Endangered or Endangered</a> by the International Union for Conservation of Nature (IUCN).</p>
<p>The <a href="http://www.nerpmarine.edu.au/sites/nerpmarine.edu.au/files//sawfish/The%20Sawfish%20Formally%20Known%20As_V2.pdf">Largetooth Sawfish</a> (<em>Pristis pristis</em>), previously known locally as the Freshwater Sawfish, is one of the planet’s largest fish, growing to over 6.5m in length. </p>
<p>The Largetooth Sawfish is a “euryhaline” species: capable of moving freely across a range of salinities from pure freshwater to the oceans. Its life cycle is complex and fascinating, encompassing a wide variety of habitats – floodplains, billabongs, creeks, rivers, estuaries and marine waters. </p>
<p>Young Largetooth Sawfish are born in estuaries before migrating upstream to spend their first 4-5 years of life in river systems. Locally they have been recorded up to <a href="http://www.environment.gov.au/resource/status-freshwater-and-estuarine-elasmobranchs-northern-australia">400 kilometres from the coast</a> in the Fitzroy River. Upon nearing maturity they move back to coastal and marine waters.</p>
<h2>Status</h2>
<p>Historically the Largetooth Sawfish was a wide-ranging species of tropical regions with four distinct populations – eastern Atlantic, western Atlantic, eastern Pacific and the Indo-west Pacific. It is now extinct or severely depleted across much of this range and is globally listed by the IUCN as <a href="http://www.iucnredlist.org/details/18584848/0">Critically Endangered</a>.</p>
<p>Northern Australia represents one of the only remaining population strongholds for this sawfish and although it has also declined significantly here, it is holding on.</p>
<p>The relatively pristine nature of large northern Australian rivers are essential for juvenile Largetooth Sawfish. We have <a href="http://www.freshwaterfishgroup.com/team-sawfish.php">some understanding</a> of the importance of rivers such as the Fitzroy River in the Kimberley and the Daly River in the Top End. However, we know little about the adult population. </p>
<p>Is the species still declining, or are protection and fisheries-management measures working? A <a href="http://www.nerpmarine.edu.au/sawfish/our-work">research project</a> is focusing on this question, using new genetic techniques to understand the species’ status.</p>
<figure class="align-center zoomable">
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<figcaption>
<span class="caption">Northern Australian is the last stronghold for the Largetooth Sawfish.</span>
<span class="attribution"><span class="source">Peter Kyne</span></span>
</figcaption>
</figure>
<h2>Threats</h2>
<p>Unregulated and unmanaged fisheries, and habitat loss and degradation, all threaten sawfish across the globe. Their long-toothed snout (or “rostrum”) is easily entangled in nets, making them susceptible to capture in a variety of fishing gear. Sawfish products, particularly their fins (used for shark fin soup) and their rostrum (sold as a curio) are highly valued.</p>
<p>Sawfish have not been commercially targeted in Australia, but have suffered from incidental capture (“bycatch”) in northern Australian gillnet and trawl fisheries. This has severely impacted Australian populations. Some fisheries now have a code of conduct to release sawfish alive, but large individuals can be difficult to handle and death from commercial fishing is an ongoing issue.</p>
<p>The Largetooth Sawfish is encountered on occasion by recreational fishers and there have been instances of <a href="http://media.murdoch.edu.au/wildlife-attacks-uncovered-at-fitzroy-river">illegal harvest</a>, including retaining the rostrum as a trophy. Fishers can follow <a href="http://www.nerpmarine.edu.au/sites/nerpmarine.edu.au/files//1-NERP_species_largetooth_sawfish_WEB_03-13.pdf">simple guidelines</a> to release sawfish safely.</p>
<p>There is <a href="https://theconversation.com/someone-is-already-using-northern-australias-water-wildlife-10788">considerable pressure</a> to develop the freshwater resources of northern Australia, but proposals will firmly need to consider impacts on Largetooth Sawfish. Structures such as dams and barrages in rivers are barriers to sawfish migration, while dry season water extraction could reduce available river habitat. Connectivity from estuaries through to upstream reaches of rivers is essential for allowing the species to complete its lifecycle.</p>
<figure>
<iframe src="https://player.vimeo.com/video/87645871" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
</figure>
<p></p><p><a href="http://vimeo.com/87645871">Sawfish survival</a> from <a href="http://vimeo.com/user15036207">Northern Biodiversity</a> on <a href="https://vimeo.com">Vimeo</a>.</p><p></p>
<h2>Strategy</h2>
<p>Globally, the IUCN Shark Specialist Group will soon release its <a href="http://www.iucnssg.org/tl_files/Assets/pdf/Sawfish/COFI_sawfish_brochure_English_small.pdf">Global Sawfish Conservation Strategy</a> which outlines a series of global objectives and actions to meet its vision: “a world where sawfishes are restored to robust populations within thriving aquatic ecosystems.” </p>
<p>These include improved fisheries management, strategic research, species and habitat protection, trade limitation, capacity building, outreach and fundraising.</p>
<p>Nationally, Australia has shown a strong commitment to sawfish conservation, particularly important given the significance of our waters for sawfishes. The Largetooth Sawfish, along with the Dwarf Sawfish and the Green Sawfish are completely protected throughout Australia. </p>
<p>The Narrow Sawfish has not been afforded that level of protection but its global threatened status warrants it, and Australia has an opportunity to continue its leadership in sawfish conservation by fully protecting this species.</p>
<p>A multi-species <a href="http://www.environment.gov.au/resource/draft-recovery-plan-sawfish-and-river-sharks-pristis-pristis-pristis-zijsron-pristis">recovery plan</a> for sawfishes and endangered <a href="http://theconversation.com/australian-endangered-species-northern-river-shark-12554">river sharks</a> is currently available for public comment. The challenge will be to turn these actions into <a href="http://www.sciencedirect.com/science/article/pii/S0006320711000565">real conservation benefits</a>.</p>
<h2>Conclusion</h2>
<p>The importance of northern Australia for Largetooth Sawfish and the other three species of threatened sawfishes which occur here cannot be overlooked. Northern Australia is like a “lifeboat” for sawfish; if they have disappeared elsewhere, Australia may be their last hope. </p><img src="https://counter.theconversation.com/content/24558/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Kyne receives funding from the Marine Biodiversity Hub and the Northern Australia Hub, collaborative partnerships supported through funding from the Australian Government’s National Environmental Research Program (NERP). He is Regional Vice-Chair of the Australia and Oceania IUCN Shark Specialist Group.</span></em></p>Sharks and rays are some of the world’s most threatened animals, with a quarter of all species at risk of extinction. Among the sharks and rays, sawfish are some of the most threatened, with all five species…Peter Kyne, Senior Research Fellow in conservation biology, Charles Darwin UniversityLicensed as Creative Commons – attribution, no derivatives.