tag:theconversation.com,2011:/fr/topics/dolphins-1928/articlesDolphins – The Conversation2024-03-04T16:54:22Ztag:theconversation.com,2011:article/2248842024-03-04T16:54:22Z2024-03-04T16:54:22ZDiscovering the world of dolphins and their three ‘super senses’<figure><img src="https://images.theconversation.com/files/579179/original/file-20240129-15-onehyv.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C4265%2C2826&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dolphins can communicate very effectively.</span> <span class="attribution"><a class="source" href="https://unsplash.com/fr/photos/photographie-en-accelere-de-deux-dauphins-nageant-dans-la-mer-ZYPQDN_xSqk">Arielle Allouche/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Imagine that you’re in a comfortable room with your cat. You’re both sharing the same space, temperature and lighting. But while you’re enjoying the décor, and perhaps a book or the taste of hot chocolate, the cat seems intrigued by something else. Maybe she’s looking for a treat or making sure that no one infringes on “her” preferred spot, a comfortable armchair near the heater.</p>
<p>All this is to say that even if you and your pet are in the same place, you both perceive your environment differently. In 1934, the German scientist Jakob von Uexküll defined it as the “umwelt” (<em>environment</em> in German). The <em>umwelt</em> is each individual’s <a href="https://monoskop.org/images/1/1d/Uexkuell_Jakob_von_A_Stroll_Through_the_Worlds_of_Animals_and_Men_A_Picture_Book_of_Invisible_Worlds.pdf">perception of the world in which he or she lives</a>.</p>
<p>But how do other animals perceive the world around them? I’m particularly interested in those that live in habitats that are drastically different from those of humans, such as dolphins in the vastness of the ocean.</p>
<p>By understanding animals’ perceptions, we can better protect them. In the case of dolphins, knowing how they perceive their environment means knowing the impact of underwater noise on their communication and taking measures to control it in protected marine areas.</p>
<p>So let’s dive in and discover the three super-senses of dolphins: magnetic perception, electrical perception and echolocation.</p>
<h2>Magnetic perception</h2>
<p>Magnetic perception was first demonstrated in dolphins in 1981: American researchers found <a href="http://www.ncbi.nlm.nih.gov/pubmed/7256282">fragments of magnetite closely linked to neuronal connections</a> extracted from the brains of four stranded common dolphins. Surprised by the discovery, the scientists suggested that it could have a sensory function or play a role in navigation.</p>
<p>In 1985, another team of researchers discovered a <a href="https://journals.biologists.com/jeb/article/120/1/1/4953/Evidence-From-Strandings-for-Geomagnetic">relationship between cetacean stranding positions and the Earth’s geomagnetic field</a>: several species of whales and dolphins actually tend to strand in places where the magnetic intensity is low. If cetaceans use the Earth’s magnetic field to find their bearings, one hypothesis is that areas where the magnetic intensity is weaker would increase the likelihood of stranding due to a lack of bearings.</p>
<p>In 2014, with a team of scientists from the University of Rennes 1, I carried out a behavioural study that enabled us to show that <a href="https://hal.science/hal-01134557">bottlenose dolphins have a magnetic sense</a>. We tested the spontaneous response of six captive dolphins to the presentation of two objects with the same shape and density: the first contained a block of magnetically charged neodymium (a metal), while the second device was completely demagnetised.</p>
<p>The dolphins approached the device much more quickly when it contained a block of strongly magnetised neodymium. This allowed us to conclude that the dolphins are able to discriminate between the two stimuli on the basis of their magnetic properties.</p>
<p>These data support the hypothesis that cetaceans can determine their location using the Earth’s magnetic field and that, consequently, when this field is weaker, the tendency to strand is greater.</p>
<h2>Electrical perception</h2>
<p>When fish move their muscles and skeletons, they emit weak electric fields. Some marine predators, particularly in benthic areas (at the bottom of the ocean) – where visibility is reduced, are able to perceive their prey via these electric fields. A range of aquatic and semi-aquatic species share this ability.</p>
<p>In dolphins, electroreception was demonstrated for the first time in 2012. The structures known as hairless <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2011.1127">vibrissal crypts</a> on the rostrum of Guiana dolphins (one of the smallest species) serve as electroreceptors. In the study, the researchers noted that the vibrissal crypts have a well-innervated ampullary structure, reminiscent of the ampullary electro-receptors in other species such as <a href="https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/elasmobranch">elasmobranchs</a> (sharks and rays), lampreys, paddlefish, catfish, certain amphibians and even in the platypus and echidna). These vibrissal crypts are thought to function as sensory receptors capable of picking up small electric fields emitted by prey in aquatic environments.</p>
<p>The same study also found behavioural evidence of electroperception. A male Guiana dolphin was trained to respond to electrical stimuli of the order of magnitude of those generated by small-to medium-sized fish. For example, a goldfish 5 to 6 centimetres long produces electric fields of 90 microvolts per centimetre, with a peak energy at 3 hertz. Bioelectric fields of 1,000 microvolts per centimetre have been reported in flounders – a magnitude equivalent to 1/100,000 of the electric current of a light bulb.</p>
<p>The dolphin was trained to place its head in a hoop and touch a target with the tip of its rostrum. It had to leave the hoop when a stimulus was presented, and when no stimulus was presented, it had to remain in the hoop for at least 12 seconds.</p>
<p>This experiment showed that dolphins perceive weak electric fields – a sensitivity comparable to that of platypus electroreceptors. The first clear demonstration of electroreception in platypuses was carried out in Canberra in 1985 by a German-Australian team, which showed that <a href="https://www.nature.com/articles/319401a0">they sought out and attacked submerged and otherwise invisible batteries</a>. In 2023, a team of researchers found similar <a href="https://pubmed.ncbi.nlm.nih.gov/38035544/">detection thresholds in bottlenose dolphins</a>, using the same behavioural test.</p>
<p>It is now thought that electroreception can facilitate the detection of prey at close range and the targeted killing of prey on the seabed.</p>
<p>In addition, the ability to detect weak electric fields could enable dolphins to perceive the Earth’s magnetic field by means of magnetoreception, which could enable them to orientate themselves on a large scale.</p>
<h2>Echolocation</h2>
<p>The most studied sense in dolphins remains <a href="https://www.frontiersin.org/articles/10.3389/fevo.2016.00049/full">echolocation</a>.</p>
<p>A more active sense than the detection of electric or magnetic fields, echolocation involves the dolphins producing sequences of clicks with their phonic lips (located in the blowhole, the nostril on the dolphin’s head). The clicks produced are highly directional, moving forward. When the sound wave touches a surface, it returns and is perceived through the dolphin’s lower jaw. In this way, they perceive sound waves extremely well, without having external ears and so retaining their smooth hydrodynamic shape.</p>
<p>Thanks to this information, the dolphin can not only know the location of a target, but also deduce its density: a dolphin can distinguish at a distance of 75 metres whether a one-inch diameter sphere (2.54 cm) is made of <a href="https://pubs.aip.org/asa/jasa/article-abstract/68/4/1077/625152/Long-range-target-detection-in-open-waters-by-an">solid steel or filled with water</a>.</p>
<h2>Dolphins communicate through channels that are inaccessible to us</h2>
<p>Dolphins’ impressive ability to “see with their ears” doesn’t stop there. Dolphins can listen to the echoes of clicks produced by their fellow dolphins, an ability known as “eavesdropping”](https://link.springer.com/article/10.3758/BF03199007). In this way, they can “share” what they detect with the members of their group and coordinate their movements.</p>
<p>As part of my research, I was interested in <a href="https://go.gale.com/ps/i.do?id=GALE%7CA491087577">how dolphins use their clicks to synchronise their movements</a>. To do this, I exploited a <a href="https://www.aquaticmammalsjournal.org/article/vol-43-iss-2-lopez-marulanda/">recording method using four hydrophones and a 360° camera</a>, which make it possible to know which dolphin is making a sound – something that was previously impossible because dolphins do not open their mouths to vocalise.</p>
<p>I was able to show that <a href="https://www.sciencedirect.com/science/article/abs/pii/S0376635721000449">when the dolphins jump synchronously in a dolphinarium, one produces the clicks while the others remain silent</a>. In our experiment, we determined that the animal that produced the clicks was always the oldest female.</p>
<p>Will the same thing happen in the wild when dolphins fish in coordination? To find out, we would need to use the same 360° audiovisual recording method in the ocean. This would involve establishing an observation base in a feeding area with good visibility – for example, when dolphins are feeding around fish farms. The regular proximity of the dolphins would make it possible to record their solitary fishing behaviour, and to better understand how they cooperate and coordinate, using all of their three “super senses”.</p><img src="https://counter.theconversation.com/content/224884/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Juliana López Marulanda is co-founder of the Macuaticos Colombia Foundation for the research and conservation of cetaceans in Colombia.</span></em></p>Let’s delve into the three super-senses of dolphins: magnetic perception, electrical perception and echolocation.Juliana López Marulanda, Enseignante chercheuse en éthologie, Université Paris Nanterre – Université Paris LumièresLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2182532023-11-24T02:53:56Z2023-11-24T02:53:56ZAustralian dolphins have the world’s highest concentrations of ‘forever chemicals’<figure><img src="https://images.theconversation.com/files/561466/original/file-20231123-15-7lw4an.JPG?ixlib=rb-1.1.0&rect=89%2C19%2C4185%2C2824&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Burrunan dolphin</span> <span class="attribution"><a class="source" href="https://www.marinemammal.org.au/gallery">Marine Mammal Foundation</a></span></figcaption></figure><p>As predators at the top of the food chain, dolphins tend to <a href="https://www.sciencedirect.com/topics/chemistry/bioaccumulation#:%7E:text=Bioaccumulation%20is%20a%20process%20of,dietary%20intake%20(trophic%20transfer).">accumulate and magnify</a> high levels of toxins and other chemicals in their bodies. So health problems in dolphins can be a warning that all is not well in the system as a whole. </p>
<p>One group of persistent pollutants has been dubbed “forever chemicals” because they almost never break down in the environment. Commonly known by the acronym PFAS, these per- and polyfluorinated substances are globally recognised as an environmental hazard and a <a href="https://doi.org/10.1002/etc.4890">potential human health issue</a>.</p>
<p>In our new research, we found dolphins with the <a href="https://doi.org/10.1016/j.scitotenv.2023.168438">highest concentration of PFAS</a> in the world live in Australian waters. One young Burrunan dolphin had liver concentrations almost 30% higher than any other dolphin ever reported.</p>
<p>This is a critically endangered species endemic to southeast Australia. While the consequences for dolphin health and the implications for humans remain unknown, the record-breaking concentrations are cause for alarm. </p>
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<h2>The case of the Burrunan dolphin</h2>
<p>The Burrunan dolphin was recognised as a <a href="https://doi.org/10.1371/journal.pone.0024047">separate species in 2011</a>. Fewer than 200 individuals remain. Two small, isolated and genetically distinct populations reside in coastal Victoria, Australia. </p>
<p>In <a href="https://doi.org/10.1016/j.scitotenv.2023.168438">our research</a>, we took liver samples from Burrunan dolphins and three other dolphin species found dead and washed up on beaches. </p>
<p>We found the critically endangered <a href="https://www.marinemammal.org.au/burrunan-dolphin">Burrunan dolphin</a> had 50–100 times more PFAS than other dolphins in the same region. Their PFAS concentrations were the highest reported globally. </p>
<p>In 90% of these dolphins, the liver concentrations of these chemicals (1,020–19,500 nanograms per gram) were above those thought to cause <a href="https://doi.org/10.1021/acs.est.5b06076">liver toxicity</a> and <a href="https://doi.org/10.1002/etc.2122">altered immune responses</a>. </p>
<p>These record-breaking and potentially health-compromising PFAS concentrations are a major concern for the survival of the species. </p>
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<a href="https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graphic illustrating the results of PFAS testing in Victorian dolphins" src="https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=232&fit=crop&dpr=1 600w, https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=232&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=232&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=291&fit=crop&dpr=1 754w, https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=291&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/561478/original/file-20231124-18-4fqtj6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=291&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The Burrunan dolphin had the highest global PFAS concentrations in the study.</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/pii/S0048969723070663?via%3Dihub">Science of The Total Environment</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Results from Australia and around the world</h2>
<p>By far the highest PFAS concentrations in the dolphins we studied were of a particular compound called PFOS (perfluorooctane sulfonate). PFOS is one of the most studied PFAS compounds. It is listed on the <a href="https://chm.pops.int/Implementation/IndustrialPOPs/PFAS/Overview/tabid/5221/Default.aspx">Stockholm Convention</a>, a global treaty on environmental pollutants, with international restrictions on use. </p>
<p>While Australia does not manufacture PFOS, heavy use of PFOS-containing firefighting foams occurred until the early 2000s. The Australian government <a href="https://www.epa.vic.gov.au/for-community/environmental-information/pfas/pfas-use-in-australia#:%7E:text=While%20PFOS%2C%20PFOA%20and%20other,as%20mist%20suppressants%20and%20coatings.">still allows PFOS import</a> for permitted purposes, such as mist suppressants in manufacturing and metal plating. </p>
<p>In recent years, public concern has prompted <a href="https://doi.org/10.1016/j.canep.2022.102296">ongoing investigations</a> into areas of high firefighting foam use, such as Royal Australian Airforce training facilities and airports. </p>
<p>While firefighting foam is a probable source of PFAS in waterways, there are others. <a href="https://theconversation.com/pfas-forever-chemicals-are-getting-into-ocean-ecosystems-where-dolphins-fish-and-manatees-dine-we-traced-their-origins-216254">Recent research in Florida</a> in the United States found leaking septic and wastewater systems in urban areas were sources of PFAS runoff into the aquatic environment. </p>
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<a href="https://theconversation.com/pfas-forever-chemicals-are-getting-into-ocean-ecosystems-where-dolphins-fish-and-manatees-dine-we-traced-their-origins-216254">PFAS 'forever chemicals' are getting into ocean ecosystems, where dolphins, fish and manatees dine – we traced their origins</a>
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<p>The Burrunan dolphins are not alone. In 2017, the <a href="https://www.epa.sa.gov.au/files/12580_report_pfas_marine.pdf">South Australian Environment Protection Authority investigated</a> PFOS concentrations in dolphins from Western Australia, South Australia and New South Wales. Dolphins in the Swan-Canning River Estuary in Perth, and in Port River or Barker Inlet, SA, had high PFOS levels (2,800–14,000ng per gram and 510–5,000ng per gram, respectively). These PFOS levels are similar to those in the Burrunan dolphin (between 494ng and 18,700ng per gram).</p>
<p>The globally significant PFAS and PFOS concentrations in multiple Australian dolphin populations demonstrates potential widespread contamination. This highlights our limited understanding of the short- and long-term consequences in our oceans and estuaries. </p>
<p>It is crucial we understand where different PFAS compounds are coming from, particularly PFOS, and whether the contamination is from a time when we didn’t know better (known as legacy sources) or if we are still releasing them. </p>
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<h2>Isn’t PFOS getting banned anyway?</h2>
<p>The Australian government has <a href="https://theconversation.com/controversial-forever-chemicals-could-be-phased-out-in-australia-under-new-restrictions-heres-what-you-need-to-know-210697">expressed an intention</a> to further regulate PFOS and two other PFAS. This marks a significant step forward. However, the problem with forever chemicals is they will be around for a really long time. </p>
<p>Typically, these chemicals are substituted with alternatives believed to be less detrimental, but unfortunately that is not always the reality. For example, early replacements for PFOS were initially thought to be less readily absorbed by body tissues and pose lower health concerns. But <a href="https://doi.org/10.1021%2Facs.est.3c00374">studies</a> have shown their high <a href="https://www.merriam-webster.com/dictionary/biomagnification">biomagnification</a> potential (with levels increasing higher up the food chain) and accompanying <a href="https://doi.org/10.1016/j.envint.2023.107846">health risks</a>.</p>
<p>While PFOS levels were highest in the Burrunan dolphins we studied, emerging contaminants such as PFMPA, PFECHS, and 6:2 Cl-PFESA were also detected. The presence of these emerging and replacement compounds in dolphins shows they are accumulating within our waterways and suggests it is more than our historic usage that might be a problem. </p>
<h2>It’s not too late</h2>
<p>Dolphins are the “canary in the coal mine” for coastal ecosystems. They live their lives in these inshore waterways and they consume tonnes of fish within their lifetimes. Finding these alarming contaminant concentrations is an important first step to highlighting the problem. </p>
<p>So now we know there’s a problem, we need to ask why. Then we need to determine what can be done about it. </p>
<p>The next step is mapping sources of PFAS so we can more effectively manage this threat to our wildlife and ecosystems. </p>
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Read more:
<a href="https://theconversation.com/we-found-long-banned-pollutants-in-the-very-deepest-part-of-the-ocean-204447">We found long-banned pollutants in the very deepest part of the ocean</a>
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<p class="fine-print"><em><span>Chantel Foord receives funding from a Holsworth Wildlife Research Endowment Grant. She is affiliated with the Marine Mammal Foundation. </span></em></p>Researchers are finding alarming concentrations of persistent pollutants such as PFAS in Australian dolphins. These record-breaking levels are cause for concern.Chantel Foord, Research Associate, Marine Mammal Foundation, PhD researcher, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2156502023-10-17T22:27:23Z2023-10-17T22:27:23ZDrought in the Amazon: Understanding the causes and the need for an immediate action plan to save the biome<p>The drought plaguing the Amazon is a worrying portrait of the climate challenges facing the world. The combination of <a href="https://www.bbc.com/news/science-environment-64192508">the El Niño phenomenon</a> and anthropogenic climate change has played a significant role in accentuating this extreme weather event. The Amazon region, known for its lush rainforest and flowing rivers, is facing a critical situation due to a lack of rainfall and rising temperatures.</p>
<p>This phenomenon, never recorded at this intensity, has affected biodiversity and human life in eight Amazonian states. <a href="https://abcnews.go.com/International/wireStory/water-life-drought-brazils-amazon-sharpening-fears-future-103815627">The drought</a> has already killed more than 140 dolphins, including pink dolphins and tucuxis, also known as grey dolphins. The mortality of fish and other aquatic animals is also high. The low volume of the rivers affects the human supply, causing a lack of drinking water and food in all the small villages, even those located on the banks of the big rivers. Of the 62 municipalities in the state of Amazonas, 42 are in a <a href="https://www.theguardian.com/world/2023/oct/10/brazil-amazon-drought-indigenous-climate-change">state of emergency</a>, 18 are in a state of alert and only two are in a normal situation.</p>
<p>The El Niño phenomenon has a direct influence on the Amazon drought. It manifests itself in the abnormal warming of the surface waters of the Pacific Ocean, affecting the rainfall regime in various parts of the world. In the case of the Amazon region, the drought is exacerbated by a decrease in humidity and a lack of rainfall, damaging the vegetation, fauna and local communities that depend on natural resources. </p>
<p>However, anthropogenic climate change is making the situation even worse. Rampant deforestation, driven by agricultural expansion and logging activity, reduces the Amazon rainforest’s ability to regulate the climate and retain moisture. In addition, the destruction of vast areas of vegetation contributes to rising temperatures, creating a cycle of even more accentuated droughts. </p>
<h2>Deforestation and mining, major factors</h2>
<p>Deforestation has been particularly devastating in the region of <a href="https://www.science.org/doi/10.1126/science.abd6977">Highway BR-319</a>, in the south of Amazonas state, driven by <a href="https://www.sciencedirect.com/science/article/abs/pii/S0264837721002829?via%3Dihub">land grabbing</a> which has provided cheap land to cattle ranchers from other states. In turn, this deforestation has increased the number of fires that feed back into the climate crisis. When they occur near riverbanks, deforestation also intensifies the <a href="https://gjeta.com/sites/default/files/GJETA-2021-0168.pdf">phenomenon known as fallen land</a>, which has drastically affected the draught of rivers and is already significantly jeopardising navigation and logistics, mainly affecting villages in the interior of the Amazon, which are already suffering from shortages.</p>
<p>Another factor that has played a significant role in affecting navigation is mining activity. Disorganised mineral extraction has created banks of land that are harmful to navigation and which, in the critical scenario of drought, have caused many vessels to run aground. </p>
<h2>The impact of hydroelectric dams</h2>
<p>Hydroelectric dams also play a role in contributing to the drought scenario, <a href="https://www.sciencedirect.com/science/article/abs/pii/S1462901113002724">especially on the Madeira River</a>. This is mainly due to the decomposition of organic matter in reservoirs created by dams, which releases methane, a potent greenhouse gas, into the atmosphere. In addition, deforestation associated with the construction of dams, as well as soil degradation and erosion resulting from the alteration of aquatic and terrestrial ecosystems, can increase emissions of carbon dioxide (CO2) and other pollutants, contributing to the impact of hydroelectric dams on climate change.</p>
<p><a href="https://news.mongabay.com/2023/10/amazon-drought-cuts-river-traffic-leaves-communities-without-water-and-supplies/">The Madeira River, now at its lowest level in almost 60 years</a>, has been drastically affected and transformed by the Jirau and Santo Antônio <a href="https://www.sciencedirect.com/science/article/abs/pii/S1462901113002724?via%3Dihub">hydroelectric dams</a>. This was due to the drastic alteration of the river’s natural flow caused by the damming of water for power generation. When water is dammed, a reservoir is formed that retains part of the water that would normally flow along the river. This diversion of the flow directly affects the region’s aquatic and terrestrial ecosystems, since the basin’s hydrological cycle is interrupted. The reduction in the volume of water in the Madeira River, for example, can lead to prolonged periods of drought, affecting not only aquatic fauna and riparian habitats, but also local communities that depend on the river for their livelihoods.</p>
<p>In addition, the construction and operation of hydroelectric dams in the Amazon often involves the clearing of significant areas of forest for the construction of dams and associated infrastructure. Deforestation contributes to a reduction in evapotranspiration, which is a crucial process for water balance in the region. With fewer trees to release water into the atmosphere, the Amazon becomes more susceptible to drought. The combination of these factors results in a significant impact on the region, making hydroelectric dams one of the causes of drought in the Amazon, particularly on the Madeira River, with worrying environmental and social consequences.</p>
<h2>What can still be done</h2>
<p>In order to combat the extreme drought in the Amazon and its devastating effects, it is essential to adopt strict measures to curb deforestation and illegal mining in the region, and for the federal government to review major undertakings such as hydroelectric dams and roads, such as the BR-319 motorway. </p>
<p>Many politicians have argued that the road, if paved, could reduce the state’s isolation, especially during droughts. However, this is a fallacious argument, because connecting the most isolated municipalities would require hundreds of kilometres of side roads, which would further increase deforestation and aggravate the climate crisis. </p>
<p>In addition, the BR-319 motorway has become a spearhead that cuts through one of the most conserved blocks of forest, linking the central Amazon, which is still preserved, to the “arc of Amazonian deforestation”, a region that concentrates most of the climate anomalies in the entire biome. </p>
<h2>Ecosystem on the edge</h2>
<p>In a <a href="https://conbio.onlinelibrary.wiley.com/doi/10.1111/cobi.14033">recent study</a> published in the renowned journal Conservation Biology, it was shown that deforestation in the Amazon is already impacting ecosystem services that are essential for Brazil, such as the Amazon’s flying rivers. This scientific data shows that we are already at the threshold of deforestation and environmental degradation tolerated by the Amazon, and more forceful action needs to be taken now. </p>
<p>Part of this responsibility lies now in the hands of President Lula, in reviewing major developments in the Amazon, such as hydroelectric dams and highways like the BR-319. In addition, it is essential to institute a zero deforestation policy that should begin this year, and not in 2030, when it will be too late. Furthermore, it is crucial that the international community and local governments work together to reduce greenhouse gas emissions and tackle climate change effectively. Only with coordinated and decisive action will we be able to mitigate the impacts of drought in the Amazon and protect this unique ecosystem that plays a vital role in regulating the global climate.</p><img src="https://counter.theconversation.com/content/215650/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lucas Ferrante has already received funding from the National Council for Scientific and Technological Development (CNPq) and the Amazonas State Research Foundation (FAPEAM)</span></em></p>A combination of climate change, a strong El Niño and an insistence on works of enormous impact are contributing to an unprecedented and extremely urgent situation in the regionLucas Ferrante, Pesquisador Vinculado ao Programa de Pós-graduação em Zoologia, Universidade Federal do Amazonas (UFAM)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1999772023-04-20T20:02:17Z2023-04-20T20:02:17ZWhale-watching guidelines don’t include boat noise. It’s time they did<figure><img src="https://images.theconversation.com/files/511111/original/file-20230220-20-3yvrjj.JPG?ixlib=rb-1.1.0&rect=36%2C0%2C4047%2C2683&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Humpback whale breach at Ningaloo. </span> <span class="attribution"><span class="source">Image: Kate Sprogis</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Imagine … eco-tourists enjoying views of undisturbed whales and dolphins, watching them doing what comes naturally.</p>
<p>This is ultimately what we all wish to see when spending time in nature watching animals. We can achieve this by using quieter boats.</p>
<p>But why do we need quieter boats? Whales and dolphins primarily use hearing to sense their surroundings (rather than sight like humans do). Sound travels almost <a href="https://oceanexplorer.noaa.gov/explorations/sound01/background/acoustics/acoustics.html#:%7E:text=Sound%20moves%20at%20a%20faster,of%20water%20differ%20from%20air.">five times faster underwater</a> than it does in the air, so it’s an important sense for whales. They rely on sounds to communicate, navigate, feed and detect predators. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0308597X23000520">Our new research</a> confirms noise from a boat watching whales at a distance of 300 metres can still disturb them. And watching whales involves a lot of boats and millions of tourists each year. This multi-billion-dollar <a href="https://www.sciencedirect.com/science/article/abs/pii/B9780128043271002624">industry</a> is active in waters off more than 100 countries. The Australian whale-watching industry is one of the biggest in the world.</p>
<p>Because the industry actively seeks out whales and dolphins, using quieter boats should be a priority. Yet current whale-watching guidelines, including <a href="https://www.agriculture.gov.au/sites/default/files/documents/aust-national-guidelines-whale-dolphin-watching-2017.pdf">Australia’s</a>, do not include noise levels. They should. </p>
<p>As the whale-watching season begins in Australia for humpback whales and southern right whales, we offer tips here for individual operators to reduce noise from their boats.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/521994/original/file-20230420-24-5p7ea.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521994/original/file-20230420-24-5p7ea.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=233&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521994/original/file-20230420-24-5p7ea.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=233&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521994/original/file-20230420-24-5p7ea.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=233&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521994/original/file-20230420-24-5p7ea.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=293&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521994/original/file-20230420-24-5p7ea.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=293&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521994/original/file-20230420-24-5p7ea.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=293&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This year’s humpback whale-watching season begins soon in Australia. Wouldn’t it be great if whale-watching guidelines set a limit on boat noise?</span>
<span class="attribution"><span class="source">Image: Kate Sprogis</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/thar-she-blows-an-experts-guide-to-whale-watching-101-171954">Thar she blows! An expert's guide to whale watching 101</a>
</strong>
</em>
</p>
<hr>
<h2>How does noise affect whales and dolphins?</h2>
<p>Besides income for local communities, whale watching has education and conservation benefits if tourists are inspired to care for the environment. </p>
<p>Despite these benefits, <a href="https://www.frontiersin.org/articles/10.3389/fmars.2021.696136/full">watching whales from a motorised boat</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0022098119301194">swimming with whales</a> can disturb their natural behaviour. For example, it might prevent them from resting or feeding, or change their breathing, swimming and dive patterns. These impacts are especially important for whales with young. </p>
<p>If the cumulative effects of these short-term impacts are not considered, they can lead to long-term consequences for the animals, such as <a href="https://www.jstor.org/stable/4124706">population declines or leaving an area altogether</a>. </p>
<p>Such outcomes are not only negative for the animals, but also for the whale-watching industry that depends on them.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/drones-gather-new-and-useful-data-for-marine-research-but-they-can-disturb-whales-and-dolphins-198985">Drones gather new and useful data for marine research, but they can disturb whales and dolphins</a>
</strong>
</em>
</p>
<hr>
<h2>Whale-watching guidelines overlook noise impacts</h2>
<p>Many countries have <a href="https://wwhandbook.iwc.int/en/responsible-management/guidelines-and-regulations">guidelines</a> on the boat’s minimum distance from the animals (typically around 100 metres), the speed at which it passes (typically below wake speed) and the approaching angle (typically from the side-rear). Guidelines, however, do not consider the noise level of the boat’s engine. A very loud boat is, in effect, considered to have the same impact on the animals as a very quiet boat.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/511107/original/file-20230220-20-vg6ih2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511107/original/file-20230220-20-vg6ih2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=341&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511107/original/file-20230220-20-vg6ih2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=341&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511107/original/file-20230220-20-vg6ih2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=341&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511107/original/file-20230220-20-vg6ih2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=428&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511107/original/file-20230220-20-vg6ih2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=428&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511107/original/file-20230220-20-vg6ih2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=428&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An example of a vessel approach to an adult whale under Australia’s whale-watching guidelines; underwater vessel noise is not considered.</span>
<span class="attribution"><span class="source">Australian National Guidelines for Whale and Dolphin Watching 2017</span></span>
</figcaption>
</figure>
<p><a href="https://elifesciences.org/articles/56760">Research</a> confirms louder boat noise disturbs whales more than quiet boat noise. Boats should be as quiet as possible. </p>
<p>We recommend a noise threshold be added to whale-watching regulations, ideally around the volume of the natural underwater background noise. At this level, boat noise is perhaps audible to the whales but with a low perceived loudness. This change to the guidelines will help minimise disturbance to whales and dolphins. </p>
<p>You can see how humpback whales change their behaviour in response to low, medium and high underwater boat noise in this video from <a href="https://elifesciences.org/articles/56760#video1">our study</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/BSdr6U2W53M?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/underwater-noise-is-a-threat-to-marine-life-197432">Underwater noise is a threat to marine life</a>
</strong>
</em>
</p>
<hr>
<h2>What do whale-watching boats sound like underwater?</h2>
<p>A range of different boats are used for whale watching worldwide. We have <a href="https://www.sciencedirect.com/science/article/pii/S0308597X21003870">calculated</a> the underwater noise level of whale-watching boats operating at low speeds. The quietest boat was a hybrid boat using its electric engines. </p>
<p>The vessel with the quieter electric engines was later used in an experiment with short-finned pilot whales. This <a href="https://www.nature.com/articles/s41598-021-00487-0">study</a> compared the whales’ responses to the boat’s quieter electric engines and its louder petrol engines. </p>
<figure class="align-center ">
<img alt="A spectrogram of a motorised whale-watch vessel passing at slow speed" src="https://images.theconversation.com/files/519716/original/file-20230406-20-ugamda.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519716/original/file-20230406-20-ugamda.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519716/original/file-20230406-20-ugamda.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519716/original/file-20230406-20-ugamda.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519716/original/file-20230406-20-ugamda.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=596&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519716/original/file-20230406-20-ugamda.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=596&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519716/original/file-20230406-20-ugamda.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=596&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A spectrogram of a motorised whale-watch vessel passing at slow speed (about 4 knots). Red shows the higher-intensity noise and blue the lower-intensity noise.</span>
<span class="attribution"><a class="source" href="https://www.sciencedirect.com/science/article/pii/S0308597X21003870">Source: Whale-watch vessel noise levels with applications to whale-watching guidelines and conservation (2021)</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>What was the result? The louder engines did indeed disturb the behaviour of short-finned pilot whales compared to the quieter engines. Notably, resting and nursing of young decreased. </p>
<p>Ultimately, some vessels are better designed to minimise noise emissions. You can hear the quieter electric-engined boat in this recording from <a href="https://www.nature.com/articles/s41598-021-00487-0">the study</a>. This makes this boat more appropriate for whale watching. </p>
<p><audio preload="metadata" controls="controls" data-duration="60" data-image="" data-title="This hybrid boat's electric engine produces much less noise underwater than its petrol engine." data-size="1449893" data-source="Author provided from Arranz et al 2021." data-source-url="https://www.sciencedirect.com/science/article/pii/S0308597X21003870" data-license="Author provided" data-license-url="">
<source src="https://cdn.theconversation.com/audio/2789/arranz-et-al-2021-sound-of-hybrid-vessel-electric-engine-from-whale-watching-paper.mp3" type="audio/mpeg">
</audio>
<div class="audio-player-caption">
This hybrid boat’s electric engine produces much less noise underwater than its petrol engine.
<span class="attribution"><a class="source" rel="nofollow" href="https://www.sciencedirect.com/science/article/pii/S0308597X21003870">Author provided from Arranz et al 2021.</a>, <span class="license">Author provided</span><span class="download"><span>1.38 MB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/2789/arranz-et-al-2021-sound-of-hybrid-vessel-electric-engine-from-whale-watching-paper.mp3">(download)</a></span></span>
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<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/511109/original/file-20230220-16-13q98k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511109/original/file-20230220-16-13q98k.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=533&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511109/original/file-20230220-16-13q98k.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=533&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511109/original/file-20230220-16-13q98k.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=533&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511109/original/file-20230220-16-13q98k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=669&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511109/original/file-20230220-16-13q98k.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=669&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511109/original/file-20230220-16-13q98k.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=669&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A mother-calf pair of pilot whales resting on the surface.</span>
<span class="attribution"><span class="source">Image: Patricia Arranz Alonso</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-scientists-need-your-help-to-spot-blue-whales-off-australias-east-coast-164620">Why scientists need your help to spot blue whales off Australia’s east coast</a>
</strong>
</em>
</p>
<hr>
<h2>Noise when arriving and departing matters too</h2>
<p>Having a quiet boat will reduce the disturbance to animals. However, even when a whale-watch operator adheres to current best-practice guidelines, there may still be disturbance. </p>
<p>This is because as a vessel increases in speed to leave the whales, it produces higher underwater noise levels. Our <a href="https://doi.org/10.1016/j.marpol.2023.105525">research</a> shows this is likely to disturb whales. So we recommend boats maintain a slow speed when approaching and departing whales – say, less than 10 knots within 1km of the whales. </p>
<p>We know it is exciting to zoom off towards a breaching whale, leaving a sleeping whale behind, but the sudden increase in boat speed and noise may then disturb that sleeping whale. </p>
<h2>5 tips to reduce boat noise</h2>
<p>On an individual level, boat operators can easily reduce disturbance to whales and dolphins by considering the following five factors.</p>
<p><strong>Speed</strong> increases noise from the propeller, so lower the speed, even when arriving/departing.</p>
<p><strong>Distance</strong>: the closer a vessel is the greater the peak in noise, so keep to the regulated distance.</p>
<p><strong>Gear shifts</strong> cause high-level noise changes, so minimise shifting.</p>
<p><strong>Approach type</strong> to the animals can cause disturbance – driving in front of their path, for example, so drive in parallel to their path.</p>
<p><strong>Movements</strong> of a boat, such as fast and erratic movements, can disturb animals, so drive consistently.</p>
<p>To further reduce noise, whale-watching companies can use larger, slower-moving propellers (to minimise the water disturbance that creates noise), quieter/electric engines and/or install noise absorption gear. </p>
<p>Both the industry and the whales will benefit from companies using quieter whale-watch boats and approaches.</p><img src="https://counter.theconversation.com/content/199977/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The multi-billion-dollar whale-watching industry enables millions of people to see these magnificent creatures up close. But the noise made by so many boats is a threat to whales’ wellbeing.Kate Sprogis, Adjunct Research Fellow, UWA Oceans Institute, The University of Western AustraliaFredrik Christiansen, Senior Researcher in Marine Biology, Aarhus UniversityPatricia Arranz Alonso, Researcher in Marine Biology, Universidad de La LagunaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1989852023-03-14T17:29:54Z2023-03-14T17:29:54ZDrones gather new and useful data for marine research, but they can disturb whales and dolphins<figure><img src="https://images.theconversation.com/files/515195/original/file-20230314-4546-vl3pg1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2790%2C1829&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Drones have allowed researchers to learn more about marine mammals.</span> <span class="attribution"><span class="source">(Jaclyn Aubin / GREMM)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Drones have changed the way researchers study whales and dolphins. While we were once confined to the decks of boats and observation platforms, glimpsing the backs of surfacing animals, we can now watch them from above. Gaining a bird’s eye view of whales and dolphins has already taught us so much about their <a href="https://doi.org/10.1002/ecs2.1468">physiology</a> and <a href="https://doi.org/10.3389/fmars.2018.00319">behaviour</a>. </p>
<p>However, there is a darker side to drone use in marine research.</p>
<p>My doctoral research investigates the behaviour of beluga whales in the St. Lawrence Estuary. I have hundreds of hours under my belt as a drone pilot, flying over these amazing and endangered animals. As a PhD student at the University of Windsor, I use drone footage of these whales to help us better understand their behaviour and social structure, particularly differences between males and females.</p>
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<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
<hr>
<h2>Observing behaviour</h2>
<p>While using drones to conduct research, I quickly noticed that the drones we flew sometimes seemed to disturb the belugas. Other colleagues sometimes observed sudden dives, where most of the animals below the drone suddenly dove, often with considerable splashing. These responses appeared to be particularly common when the drone was flown at low altitudes, around 20 meters above the water. </p>
<p>We were concerned that this disturbance could impact our ability to study the whales, and worse, could have a negative impact on the whales themselves.</p>
<p>We conducted research into our observations, and our findings were <a href="https://doi.org/10.1111/mms.12997">published in <em>Marine Mammal Science</em></a>. We examined whether a series of variables relating to drone piloting impacted the likelihood of the belugas responding to the drone. </p>
<p>We predicted that responses to the drone would increase at low drone altitudes, when the drone’s speed increased (increasing the noise of the rotors), when the drone approached the whales head-on, when wind speeds were low (making the drone more easy to hear), and on the first flight of the day. </p>
<p>We also examined variables relating to the whales being observed and predicted that drone disturbance would increase when the whales were in small groups, when offspring were present and when the whales were resting.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CjA88j-udD7","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Drone altitudes</h2>
<p>We found that sudden dives were relatively rare, only occurring in about four per cent of observations. However, sudden dives appeared to increase when drone altitude decreased. Sudden dives were particularly common when the drone was flown below 23 metres in altitude. This finding made sense to us: we had observed the drone was much more noticeable when flying directly above our heads, compared to when it was flying at 100 metres of altitude.</p>
<p>We also found that sudden dives appeared to be more common when flying over large groups. This finding was unexpected: earlier studies on dolphins have suggested that <a href="https://doi.org/10.3389/fmars.2018.00316">small groups are more prone to disturbance</a>. </p>
<p>However, a <a href="https://doi.org/10.1002/aqc.3440">recently published study examining the impact of drones on bottlenose dolphins</a> found the same trend of disturbance increasing with group size. These authors suggested this is due to the “many eyes” effect, where large groups are more vigilant because there are more animals scanning for threats.</p>
<p>We also found that sudden dives commonly occurred when the drone first approached the whales. This suggests that the whales may be spooked by the initial approach of the drone.</p>
<h2>Observer effects</h2>
<p>We also conducted a literature review examining the impact of drone altitude on other whale and dolphin species. We found that drone disturbance rarely occurred when the drone was flown above 30 metres in altitude. </p>
<p>Interestingly, drone disturbance seemed more likely to be reported when authors included <a href="https://doi.org/10.1002/wsb.1240">detailed descriptions of how disturbance was assessed and measured</a>, suggesting that drone disturbance may be missed when researchers are not specifically looking for it. </p>
<p>We also found that most studies examining the impact of drones on whales and dolphins used small drones (less than five kilograms) which are much more discrete than the large, over 10 kilogram drone models that are frequently used in modern research programs.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/pvLJGl8hkeg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drone footage of beluga whales chasing a fish.</span></figcaption>
</figure>
<h2>Future recommendations</h2>
<p>Our findings prompted us to make seven recommendations for future drone studies of whales and dolphins: </p>
<ol>
<li><p>Drone studies of belugas should maintain an altitude of 25 metres or more. </p></li>
<li><p>Researchers using drones to study whales and dolphins should weigh the conservation benefit of low altitude flights against the potential for disturbance. </p></li>
<li><p>Pilots should use special caution when flying over large groups. </p></li>
<li><p>Pilots should use special caution when first approaching a group. </p></li>
<li><p>Pilots using large drones (those weighing more than 10 kilograms) should be particularly vigilant to drone disturbance and should report on the effects of large drones on whales and dolphins. </p></li>
<li><p>Future drone studies should clearly define the disturbance behaviours they will watch for.</p></li>
<li><p>Using a precautionary approach, drone pilots should avoid sudden accelerations, avoid approaching animals head-on and maintain special caution in low wind conditions.</p></li>
</ol>
<p>By reducing the disturbance impact of research on whales and dolphins, we can help protect these amazing animals.</p><img src="https://counter.theconversation.com/content/198985/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaclyn Aubin receives funding from the Natural Sciences and Engineering Research Council of Canada.</span></em></p>Drones are a new technology that help researchers observe and record whale behaviours from a distance. But if the drones are flown too low, they change the whales’ behaviour.Jaclyn A. Aubin, PhD candidate, Integrative Biology, University of WindsorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1974322023-01-17T12:31:09Z2023-01-17T12:31:09ZUnderwater noise is a threat to marine life<p>Oceans are full of sound. Waves, earthquakes and calving icebergs all contribute to the underwater soundscape. But so do human activities, and this can be a problem for marine life as it can seriously affect their physiology, behaviour, reproduction and even survival.</p>
<p>Being able to produce and detect sound in an environment where light penetrates only a few hundred metres is crucial for animals to communicate, feed, avoid predators and navigate vast underwater habitats. Large whales generate low frequency communication calls that can travel <a href="https://www.bbcearth.com/news/the-loudest-voice-in-the-animal-kingdom">thousands of kilometres</a>. While the <a href="https://www.science.org/doi/full/10.1126/science.289.5487.2114">snapping shrimp</a>, native to the western Atlantic, can produce a loud snapping sound capable of stunning and killing its prey.</p>
<p>The noise generated by humans <a href="https://www.science.org/doi/10.1126/science.aba4658">changes the natural acoustic environment</a> of our oceans and our capacity to produce it is increasing. Noise is often the unintentional byproduct of transport, infrastructure development and industry. </p>
<p>Yet noise can also be produced deliberately. Many navies use sonar to detect ships and submarines, while geologists survey the seabed for oil and gas using <a href="https://dosits.org/animals/effects-of-sound/anthropogenic-sources/seismic-airguns/">seismic airguns</a>. The noise produced by an airgun can exceed 200 decibels (louder than a gunshot at a range of one metre).</p>
<p>Sound travels further and <a href="https://en.wikipedia.org/wiki/Speed_of_sound">four times faster</a> in water than in air (at a speed of almost 1,500 metres per second). The noise produced by humans can therefore spread considerable distances underwater. These sounds can be relatively constant, such as the noise produced by a ship’s engine and propeller, or sudden and acute in the case of naval sonar and seismic airguns. </p>
<h2>Can noise kill?</h2>
<p>The sound produced by a seismic airgun can cause permanent hearing loss, tissue damage and even death in nearby animals. </p>
<p>Evidence for the lethal effects of noise can be hard to document in the open ocean. But seismic surveys have been linked to the mass mortality of <a href="https://tethys.pnnl.gov/publications/review-records-giant-squid-north-eastern-atlantic-severe-injuries-architeuthis-dux">squid</a> and <a href="https://academic.oup.com/bioscience/article/68/12/1024/5160052">zooplankton</a>. In 2017, research revealed that a single air gun caused the death rate of zooplankton to increase from 18% to 40–60% over a 1.2 kilometre stretch of the ocean off the coast of southern Tasmania.</p>
<p>The use of <a href="https://www.sciencedirect.com/science/article/pii/S0025326X08002221">naval sonar</a> has also been associated with the mass stranding of several whale species in the Caribbean, Europe and East Asia. Mass stranding events involve entire pods of animals simultaneously beaching themselves. </p>
<p>Examination of the dead whales revealed they had suffered trauma similar to decompression sickness. This was believed to have been caused by sudden changes in their deep diving behaviour following exposure to sonar. </p>
<h2>Arrested development</h2>
<p>Over the past two decades, research has also revealed the widespread impact of chronic noise exposure on <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12207">animal behaviour and physiology</a>. These impacts can extend well beyond the noise source and affect vast areas of the ocean. </p>
<p><a href="https://www.nature.com/articles/srep05891?origin=ppub">Laboratory studies</a> on the <a href="https://oceaninfo.com/animals/sea-hare/">sea hare</a> – a marine slug – revealed that exposure to boat noise led to a 21% reduction in successful embryo development. Individuals that hatched also suffered a 22% higher death rate than sea hares that were not exposed to boat noise. </p>
<p>These findings demonstrate the negative effects that a common source of underwater noise can have on animal development and survival. If these laboratory results can be applied to natural environments then such impacts could threaten entire populations of marine species in particular areas.</p>
<figure class="align-center ">
<img alt="A sea hare attached to a rock underwater." src="https://images.theconversation.com/files/504284/original/file-20230112-14-f24d9d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/504284/original/file-20230112-14-f24d9d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/504284/original/file-20230112-14-f24d9d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/504284/original/file-20230112-14-f24d9d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/504284/original/file-20230112-14-f24d9d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/504284/original/file-20230112-14-f24d9d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/504284/original/file-20230112-14-f24d9d.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">Embryonic development in sea hares was reduced when exposed to boat noise.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/underwater-shot-on-large-sea-hare-1807396141">Vojce/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Disrupted behaviour</h2>
<p>Observing the movements, feeding, communication, resting and social interactions of animals provides scientists with a method for exploring the <a href="https://theconversation.com/how-noise-pollution-is-changing-animal-behaviour-52339">effects of noise</a>. </p>
<p>The behavioural impacts of noise on marine mammals are particularly well studied due to conservation concerns and their reliance on sound for communication, foraging and navigation. Many of these species move large distances and long-range communication is crucial for coordinating social interactions and reproduction. </p>
<p>But the sounds produced by large marine mammals are of a similar low frequency range to much of the noise produced by humans. The noise produced by ships tends to be <a href="https://www.sciencedirect.com/science/article/pii/S0025326X20300667">below 2 kHz</a> which overlaps with the vocal frequencies produced by many large mammals. <a href="https://asa.scitation.org/doi/10.1121/1.1593066">Blue whales</a>, for example, produce frequency vocalisations of less than 100 Hz meaning their calls can be lost in the background din.</p>
<p>Shipping noise has led to marine mammals altering their vocalisation patterns. This includes making calls longer and more repetitive or waiting until noise levels drop before calling. Research has shown that shipping noise made within 1,200 metres of <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0204112">humpback whales</a> has caused the whales to either reduce or stop their calling in the waters surrounding the remote <a href="https://whc.unesco.org/en/list/1362/">Ogasawara Islands</a> in Japan.</p>
<p>Despite these vocal adaptations, noise can negatively affect animals’ feeding behaviour and increase physiological stress. <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2011.2429">Research</a> found that a reduction in shipping following the 9/11 terrorist attacks led to a six decibel drop in noise levels in the Bay of Fundy on Canada’s Atlantic coast. This coincided with lower levels of physiological stress detected in <a href="https://www.fisheries.noaa.gov/species/north-atlantic-right-whale">North Atlantic right whales</a> when researchers measured stress hormones from floating whale faeces.</p>
<p>The COVID-19 lockdowns also led to previously busy waterways being used more frequently by large marine animals. For example, dolphin numbers – including the endangered <a href="https://www.reuters.com/article/health-coronavirus-hongkong-dolphins-idINKBN2650B0">pink dolphin</a> – increased in the waters around Hong Kong following temporary restrictions on ferry traffic.</p>
<p>Noisy oceans are having a profound negative impact on marine life. Taking action to protect and restore natural soundscapes is a key priority for conservation. </p>
<p>The good news is that noise is removed from the environment as soon as the sound source is switched off or turned down. Technological developments in ship design, such as <a href="https://www.rivieramm.com/opinion/opinion/a-quiet-revolution-in-underwater-noise-54783">reduced propellor cavitation</a> (the formation of air bubbles on the surface of a propeller), have already <a href="https://www.sciencedirect.com/science/article/pii/S0003682X18300021">lowered</a> the noise produced by ships. </p>
<p>Small adjustments in speed can also substantially lower engine and propeller noise. <a href="https://web.p.ebscohost.com/abstract?site=ehost&scope=site&jrnl=17183200&AN=95846538&h=HnGgvltyT4fzxuRUwoAFioh3Q8aXl41naC8CF7n6px%2bSTWTrT9CpM2Tv6UJlU393O3pCtkmBJVmdLpkHgB0NsQ%3d%3d&crl=c&resultLocal=ErrCrlNoResults&resultNs=Ehost&crlhashurl=login.aspx%3fdirect%3dtrue%26profile%3dehost%26scope%3dsite%26authtype%3dcrawler%26jrnl%3d17183200%26AN%3d95846538">Research</a> has found that a 15.6 to 13.8 knot reduction in the average speed of commercial ships can reduce underwater noise pollution by more than 50%. </p>
<p>But global awareness of the impact of noise on ocean health needs improving and policies aimed at managing sound and implementing technological solutions must be more rigorous. These are readily available solutions that promise a brighter – and quieter – future for our oceans.</p><img src="https://counter.theconversation.com/content/197432/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Graeme Shannon 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>Noisy oceans are having a significant impact on marine life.Graeme Shannon, Lecturer in Zoology, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1961302023-01-12T13:22:53Z2023-01-12T13:22:53ZLobsters versus right whales: The latest chapter in a long quest to make fishing more sustainable<figure><img src="https://images.theconversation.com/files/503915/original/file-20230110-16-cf67f9.jpg?ixlib=rb-1.1.0&rect=30%2C7%2C5061%2C3344&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lobster fishing uses a lot of rope, and whales can die after becoming entangled in it. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/lobster-traps-and-ropes-on-a-dock-chatham-cape-cod-ma-news-photo/170495599">MyLoupe/Universal Images Group via Getty Images</a></span></figcaption></figure><p>Maine lobster fishermen received a Christmas gift from Congress at the end of 2022: A <a href="https://www.npr.org/2022/12/30/1146367811/maines-lobster-industry-wins-against-endangered-right-whale-protections">six-year delay</a> on new federal regulations designed to protect <a href="https://www.fisheries.noaa.gov/species/north-atlantic-right-whale">critically endangered North Atlantic right whales</a>. </p>
<p>The rules would have required lobstermen to create new seasonal nonfishing zones and further reduce their use of vertical ropes to retrieve lobster traps from the seafloor. Entanglement in fishing gear and collisions with <a href="https://www.fisheries.noaa.gov/insight/understanding-vessel-strikes">many types of ships</a> are the <a href="https://www.fisheries.noaa.gov/species/north-atlantic-right-whale">leading causes of right whale deaths</a>. </p>
<p>Maine’s congressional delegation amended a federal spending bill to <a href="https://www.npr.org/2023/01/04/1146637583/maine-lobster-industry-wins-reprieve-but-environmentalists-say-whales-will-die">delay the new regulations until 2028</a> and called for more research on whale entanglements and <a href="https://theconversation.com/high-tech-fishing-gear-could-help-save-critically-endangered-right-whales-115974">ropeless fishing gear</a>. Conservationists argue that the delay could drive North Atlantic right whales, which number about 340 today, <a href="https://biologicaldiversity.org/w/news/press-releases/right-whale-condemned-to-extinction-in-senate-omnibus-2022-12-20/">to extinction</a>.</p>
<p>This is the latest chapter in an ongoing and sometimes fraught debate over fishing gear and <a href="https://www.fisheries.noaa.gov/node/251">bycatch</a> – unintentionally caught species that fishermen don’t want and can’t sell. My research as a <a href="https://scholar.google.com/citations?user=rDxMAlQAAAAJ&hl=en">maritime historian</a>, focusing on disputes tied to industrial fishing, shows the profound impacts that particular fishing gear can have on marine species. </p>
<p>Disputes over fishing gear and bycatch have involved consumers, commercial fishermen, recreational anglers and environmentalists. With conservation pitted against economic livelihoods, emotions often run high. And these controversies aren’t resolved quickly, which bodes poorly for species on the brink. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1569853496551260160"}"></div></p>
<h2>Millions of tons wasted</h2>
<p>Bycatch is difficult to measure. Estimates vary widely, but scientists have calculated that <a href="https://doi.org/10.1111/faf.12233">10% to 40% of total yearly catches worldwide</a> are species that weren’t targeted, including fish, whales, dolphins, turtles and <a href="https://www.fisheries.noaa.gov/national/science-data/seabirds">seabirds</a>.</p>
<p>According to the United Nations, global fishery harvests totaled <a href="https://www.fao.org/3/cc0461en/cc0461en.pdf">178 million tons</a> in 2020. Even by the most conservative estimates, then, some 20 million tons are likely wasted annually. Advocacy focuses on high-profile species like sea turtles, dolphins and sharks, but the problem is much more pervasive. <a href="https://media.fisheries.noaa.gov/dam-migration/nbr_update_3.pdf">Recent studies of U.S. Atlantic fisheries</a> indicate that flounder, herring and halibut are among the species most frequently landed as bycatch. </p>
<p>At the same time, global demand for fish is rising. From 1961 to 2019, world fish consumption <a href="https://www.fao.org/3/cc0461en/cc0461en.pdf">grew by an average of 3% annually</a>, and yearly per capita consumption increased from 22 pounds (10 kilograms) to 46 pounds (21 kilograms). Today, fish consumption is split evenly between aquaculture, or farmed fish, and wild-capture fisheries, where bycatch occurs. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bjFSgr_B38I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bycatch is a major global problem that kills fish, marine mammals, sea turtles and seabirds.</span></figcaption>
</figure>
<h2>Dolphin-free tuna</h2>
<p>Most wild-catch fishing takes place far from shore, so bycatch occurs out of the public spotlight. Sometimes, though, threats to charismatic species make news.</p>
<p>Perhaps the most prominent example is U.S. consumers’ campaign against the tuna fishing industry for killing dolphins. In the 1950s, tuna fishermen adopted the <a href="https://www.fisheries.noaa.gov/national/bycatch/fishing-gear-purse-seines">purse seine</a> – a long, rectangular net that hangs vertically in the water. Boats encircled schools of fish with these nets, then cinched them at the top and bottom. Some nets extended hundreds of feet deep and more than a mile from end to end. </p>
<p>Purse seines often swept up dolphins that swam alongside tuna. Using a method called “setting on dolphins,” tuna fishermen would <a href="https://doi.org/10.3389/fmars.2021.754755">search for pods of dolphin feeding at the surface</a>, which generally indicated that tuna were beneath them feeding as well. By the 1960s, it was estimated that nearly <a href="https://doi.org/10.1111/mms.12996">a quarter of a million dolphins were dying every year</a> when they became trapped in nets and suffered traumatic injuries or suffocated. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Label with an image of a dolphin and 'U.S. Department of Commerce/Dolphin Safe.'" src="https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/503917/original/file-20230110-4937-zh28b4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Logo approved by U.S. regulators in 2000 for tuna caught without targeting dolphins.</span>
<span class="attribution"><a class="source" href="https://media.fisheries.noaa.gov/dam-migration-miss/md_1FATNuBUz24L.jpg?1510953130">NOAA</a></span>
</figcaption>
</figure>
<p>When Congress held hearings in the early 1970s on a proposed <a href="https://www.ucpress.edu/book/9780520261846/american-tuna">ban on the capture of all species of whales</a>, including dolphins, this practice sparked outrage. The New York Times <a href="https://www.nytimes.com/1972/03/19/archives/the-great-porpoise-massacre-despite-the-tuna-fishermens-advanced.html">accused the tuna industry of “wanton slaughter</a>.” Millions of viewers watched televised documentaries with titles like “<a href="https://www.youtube.com/watch?v=myU1g3D-Mis">Last Day of the Dolphins?</a>” and “<a href="https://www.youtube.com/watch?v=nY6NHyYqFJw&t=22s">Where Have All the Dolphins Gone?</a>” Advocacy groups campaigned with slogans like “<a href="https://content.time.com/time/subscriber/article/0,33009,961907,00.html">Would You Kill Flipper for a Tuna Sandwich?</a>” and <a href="https://www.latimes.com/archives/la-xpm-1988-04-12-mn-795-story.html">boycotted canned tuna</a>.</p>
<p>Under pressure, major suppliers including StarKist, Chicken of the Sea and Bumble Bee pledged to use only tuna that was not caught using methods that endangered dolphins. In 1990, Congress passed legislation creating a label that identified canned tuna caught appropriately as “<a href="https://www.ers.usda.gov/webdocs/publications/41203/18892_aer793f.pdf">dolphin-safe</a>.” Other measures <a href="https://doi.org/10.3389/fmars.2021.754755">banned tuna imports</a> from countries with dolphin mortality rates higher than those in U.S. fisheries.</p>
<h2>Trap doors for turtles</h2>
<p>The spotlight next shifted to the U.S. Gulf Coast, where shrimp catches were skyrocketing thanks to gear like <a href="https://www.fisheries.noaa.gov/national/bycatch/fishing-gear-midwater-trawls">otter trawls</a> – large conical nets towed through the water behind fishing boats. By some estimates, for every 1,000 pounds of fish that these nets gathered, <a href="https://www.google.com/books/edition/The_Bay_Shrimpers_of_Texas/QV4QAQAAIAAJ?hl=en&gbpv=1&bsq=1000%20pounds">less than 100 pounds was marketable shrimp</a>. Other species – usually dead, dying or injured – were tossed overboard.</p>
<p>Environmentalists and recreational anglers accused the fishing industry of endangering popular sport fish, such as red drum and spotted trout. But sea turtles, which often were found in the same coastal waters as shrimp, became critics’ poster animal. A 1990 report from the National Research Council estimated that shrimping killed <a href="https://nap.nationalacademies.org/read/1536/chapter/2#5">up to 55,000 Kemp’s ridley and loggerhead sea turtles yearly</a>.</p>
<p>Federal regulators initially proposed voluntary use of <a href="https://www.seagrantfish.lsu.edu/management/TEDs&BRDs/teds_history.htm">turtle excluder devices, or TEDs</a> – small trap doors in fishing nets that could allow captured turtles to swim free. In 1987, the National Oceanic and Atmospheric Administration <a href="https://www.fisheries.noaa.gov/southeast/bycatch/history-turtle-excluder-devices">published mandatory TED usage regulations</a>, which went into effect in 1989 after several years of lawsuits, injunctions and state legal action. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/F7j5yXnZo2Y?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Turtle excluder devices, or TEDs, direct sea turtles toward openings in shrimp nets that allow the turtles to escape.</span></figcaption>
</figure>
<p>Many fishermen argued that TEDs greatly reduced their shrimp catches and resisted the new regulations, <a href="https://www.upi.com/Archives/1989/07/23/Shrimper-blockade-dismantled-as-small-protest-continues/6163617169600/">sometimes agressively</a>. Over time, however, shrimpers began working with federal regulators to develop and test TEDs that <a href="https://spo.nmfs.noaa.gov/sites/default/files/pdf-content/MFR/mfr742/mfr7423.pdf">released turtles and retained shrimp more effectively</a>. Today, sea turtles are <a href="https://www.iucn-mtsg.org/statuses">still at risk</a>, but there is wide agreement that modern TEDs effectively reduce turtle bycatch. Conservation organizations are working to <a href="https://www.iucncongress2020.org/motion/097">increase their use worldwide</a>.</p>
<h2>Slow progress</h2>
<p>Fishermen often are quick to rebut claims that their methods endanger other species. They typically assert that their fishing <a href="https://doi.org/10.1093/icesjms/fsac045">has little impact on the broader ecosystem</a> and that new gear and practices will be <a href="https://www.nationalfisherman.com/national-international/why-everything-you-ve-heard-about-ropeless-crab-fishing-gear-is-false">too costly or ineffective</a> against a minor problem. </p>
<p>Ultimately, public pressure – including <a href="https://defenders.org/sites/default/files/2022-07/219_MSJ%20opinion.pdf">lawsuits</a> – can lead to regulation, especially when a potent symbol like dolphins, sea turtles or, perhaps, right whales, is threatened. The Maine lobster fishery has lost several <a href="https://www.usatoday.com/story/news/nation/2022/09/10/lobster-red-list-maine-seafood-watch/8048412001/">sustainable</a> <a href="https://www.msc.org/en-us/media-center/news-media/press-release/msc-certificate-suspended-for-gulf-of-maine-lobster-fishery">certifications</a> because of concerns about right whale entanglements.</p>
<p>But regulation isn’t enough. Reducing dolphin and sea turtle bycatch also required <a href="https://doi.org/10.1093/icesjms/fsac210">extensive engagement between regulators and fisheries</a> to educate fishermen and develop and test gear. It’s not clear whether this will happen fast enough to save North Atlantic right whales. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1563283487402381312"}"></div></p>
<p>Across broad swaths of the globe, including much of Africa and Asia, more than 3 billion people obtain <a href="https://www.fao.org/3/ca9229en/online/ca9229en.html#chapter-1_1">from 20% to over 50%</a> of the animal protein in their diets from aquatic sources. Rising demand for wild-caught fish is likely to increase bycatch. In my view, unintentional capture of any species – whether it’s a winsome <a href="https://iwc.int/about-whales/whale-species/spinner-dolphin">spinner dolphin</a> or a <a href="https://doi.org/10.1002/aqc.1202">bottom-dwelling scavenger like the hagfish</a> – harms the ocean’s ecological health and threatens communities that rely on the sea for sustenance.</p><img src="https://counter.theconversation.com/content/196130/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Blake Earle does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>To fish the oceans sustainably, nations must reduce bycatch, or accidental catches. But fishermen often resist changing gear or techniques that kill nontargeted species.Blake Earle, Assistant Professor of History, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1934572023-01-02T19:44:56Z2023-01-02T19:44:56ZWhen we swim in the ocean, we enter another animal’s home. Here’s how to keep us all safe<figure><img src="https://images.theconversation.com/files/501731/original/file-20221219-11129-flr0fc.jpg?ixlib=rb-1.1.0&rect=23%2C7%2C5176%2C3453&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Every summer, many Australians head to the ocean to swim, surf, sail, kayak, and walk along the beach. </p>
<p>But humans are not alone when we use the ocean. Fish, seals, dolphins, sharks, jellyfish, turtles, stingrays, cuttlefish, and birds often swim alongside us. When we enter the ocean we become part of an entangled web of animal relationships.</p>
<p>Encountering animals when we swim and surf in the ocean is fun and exciting. But sharing the water with animals also <a href="https://www.tandfonline.com/doi/full/10.1080/02614367.2022.2149842">comes with</a> the risk of stings, bites, frights, and injury to us. It can also bring harm to ocean wildlife.</p>
<p>By educating ourselves about marine life, humans can minimise risks to ourselves and the animals who call the ocean home.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/reel/CR5S0o8nMhO/?igshid=YmMyMTA2M2Y%3D","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>We can frighten animals – and they can scare us</h2>
<p>Despite how vulnerable we feel when swimming, our presence in the ocean can frighten or harm an animal. Animals may see us as a predator and alter their behaviour accordingly.</p>
<p>Fish, birds and small stingrays might swim off, and turtles might delay rising to the ocean’s surface to breathe. </p>
<p>Not all animals are frightened of humans. It’s a highlight when curious dolphins swim and play around us. But dolphins can attack humans or other animals if they <a href="https://www.ingentaconnect.com/content/cog/tme/2020/00000015/f0020003/art00008">feel threatened</a> - for example when feeding or protecting their young.</p>
<p>Humans can also be scared of animals in the water. This fear drives the use of shark nets off beaches or, less commonly, shark culls.</p>
<p>Shark nets are controversial – not least because they can <a href="https://theconversation.com/why-do-whales-keep-getting-tangled-in-shark-nets-and-what-should-you-do-if-you-see-it-happen-186468">entangle and kill</a> animals including turtles, non-target sharks, stingrays, and whales. </p>
<p>Even more controversial are shark culls, such as those <a href="https://theconversation.com/western-australias-shark-culls-lack-bite-and-science-21371">planned</a> for Western Australia in 2013 after a spate of fatal shark attacks. The plan was later <a href="https://www.theguardian.com/environment/2014/oct/24/wa-abandons-shark-culling-program-but-reserves-right-to-kill-again">abandoned</a>, after it was criticised as cruel and <a href="https://www.theguardian.com/world/2014/jul/04/wa-shark-cull-condemned-by-global-group-of-marine-scientists">lacking</a> scientific basis.</p>
<p>Killing or harming ocean animals so humans can have fun in the water raises all sorts of <a href="https://ro.uow.edu.au/asj/vol7/iss1/13/">questions</a> and moral dilemmas. So how else might we keep ourselves safe in the ocean?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/shark-nets-are-destructive-and-dont-keep-you-safe-lets-invest-in-lifeguards-127453">Shark nets are destructive and don't keep you safe – let's invest in lifeguards</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="Hammerhead shark caught in net" src="https://images.theconversation.com/files/501738/original/file-20221219-20-3cltme.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501738/original/file-20221219-20-3cltme.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501738/original/file-20221219-20-3cltme.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501738/original/file-20221219-20-3cltme.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501738/original/file-20221219-20-3cltme.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501738/original/file-20221219-20-3cltme.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501738/original/file-20221219-20-3cltme.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">
<figcaption>
<span class="caption">Shark nets can kill non-target species, such as this hammerhead shark trapped off the Gold Coast.</span>
<span class="attribution"><span class="source">Sea Shepherd</span></span>
</figcaption>
</figure>
<h2>Learn about ocean animals</h2>
<p>Learning about what ocean animals you might encounter – and when – can help keep both people and animals safe.</p>
<p>Some animals are present year-round. But, as whale watchers and fisherman are well aware, many animals are more active in a particular seasons or only appear at certain times of the year. </p>
<p>For example, in cooler months in the waters off northern Australia, <a href="https://australian.museum/learn/animals/fishes/manta-ray-manta-birostris/">manta rays</a> are most active. <a href="https://search.informit.org/doi/pdf/10.3316/ielapa.702610524429802">Leopard sharks</a>, meanwhile, appear during warmer months in southeast Queensland and northeast New South Wales. </p>
<p>And from November until May or June, a variety of <a href="https://www.abc.net.au/news/2022-10-31/stinger-season-north-queensland-warning/101597638">marine stingers</a> can be found in the coastal waters of Far North Queensland. These include the potentially lethal box jellyfish. </p>
<p>Informing ourselves means we can take measures to keep safe. For example, people swimming in North Queensland in the warmer months are <a href="https://www.visitcairns.com.au/stingerseasoncairns.htm">advised to</a> swim at netted beaches, and wear wetsuits or stinger suits. Entering the water slowly also gives some marine stingers time to move away.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/want-to-avoid-a-bluebottle-sting-heres-how-to-predict-which-beach-theyll-land-on-179947">Want to avoid a bluebottle sting? Here's how to predict which beach they'll land on</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="sign depicting person caught by stinger" src="https://images.theconversation.com/files/501736/original/file-20221219-11243-gy294k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501736/original/file-20221219-11243-gy294k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501736/original/file-20221219-11243-gy294k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501736/original/file-20221219-11243-gy294k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501736/original/file-20221219-11243-gy294k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501736/original/file-20221219-11243-gy294k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501736/original/file-20221219-11243-gy294k.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">Ocean-goers in North Queensland should know when marine stingers are about.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>When it comes to sharks, there are <a href="https://theconversation.com/shark-nets-are-destructive-and-dont-keep-you-safe-lets-invest-in-lifeguards-127453">growing calls</a> to adopt non-violent approaches to minimise risks to humans. This could include public education on, for example, links between fish seasons and shark activity. </p>
<p>Educating ourselves about ocean animals also helps us protect them.</p>
<p><a href="https://birdlife.org.au/projects/beach-nesting-birds">Shorebirds</a>, for instance, nest in spring and summer. This is prime beach time for people, too. Shorebird nests are shallow and vulnerable, and birds will often abandon their eggs when humans are around. Dogs and 4WDs pose an even <a href="https://theconversation.com/contested-spaces-saving-nature-when-our-beaches-have-gone-to-the-dogs-72078">bigger threat</a>.</p>
<p>If we know we’re sharing a beach with nesting shorebirds, we can take steps to ensure their safety, such as keeping our dogs on a leash and avoiding using dunes and other common nesting areas.</p>
<p>The annual migration of whales and their calves up and down our coasts is an exciting time to visit the beach and, if you’re lucky, to view a splashy show of breaching or water slapping. </p>
<p>But if you plan to go sailing or kayaking, be aware of rules around interacting with whales. They law states they can approach us, but we <a href="https://www.dcceew.gov.au/environment/marine/publications/australian-national-guidelines-whale-and-dolphin-watching-2017">must not</a> get too close to them.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/this-birds-stamina-is-remarkable-it-flies-non-stop-for-5-days-from-japan-to-australia-but-now-its-habitat-is-under-threat-165964">This bird's stamina is remarkable: it flies non-stop for 5 days from Japan to Australia, but now its habitat is under threat</a>
</strong>
</em>
</p>
<hr>
<p>If you’re not an experienced ocean user, or don’t know about the animals living in a particular place, talk to someone who is informed. </p>
<p>If you use beaches patrolled by surf lifesavers they can give you information about animals that might be present that day, such as sharks or jellyfish. They can also tell you about ocean conditions such as rips, currents and water quality.</p>
<p>If you do suffer a painful bluebottle or jellyfish sting, surf lifesavers may also provide basic <a href="https://beachsafe.org.au/surf-safety/marine-stingers">treatments</a> such as dousing the sting with hot water or vinegar.</p>
<p>If you’re planning to swim or surf at unpatrolled beaches – especially if they’re remote – pack a basic first aid kit including sunscreen, vinegar and instant ice packs.</p>
<p>And remember, enjoying time in the ocean with other poeple is <a href="https://journals.sagepub.com/doi/full/10.1177/0193723520928594">safer than</a> swimming alone.</p>
<figure class="align-center ">
<img alt="boy with boogie board and other swimmers" src="https://images.theconversation.com/files/501764/original/file-20221219-13-4o0pxv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501764/original/file-20221219-13-4o0pxv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=359&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501764/original/file-20221219-13-4o0pxv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=359&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501764/original/file-20221219-13-4o0pxv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=359&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501764/original/file-20221219-13-4o0pxv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501764/original/file-20221219-13-4o0pxv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501764/original/file-20221219-13-4o0pxv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=451&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It’s safer to swim with others than alone.</span>
<span class="attribution"><span class="source">Jason O'Brien/AAP</span></span>
</figcaption>
</figure>
<h2>Ensuring everyone enjoys the encounter</h2>
<p>Despite the risks, most human encounters with animals in the ocean are <a href="https://theconversation.com/why-going-for-a-swim-in-the-ocean-can-be-good-for-you-and-for-nature-150281">exciting</a> and positive. </p>
<p>Learning about the kinds of animals you might come across, as well as the best ways to interact with them, will help keep you safe – and make sure its a good experience for the animals too.</p><img src="https://counter.theconversation.com/content/193457/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rebecca Olive receives funding from The Australian Research Council. </span></em></p>Swimming and surfing in the ocean is fun and invigorating. But sharing the water with animals comes with risks to us and them.Rebecca Olive, Vice Chancellor's Senior Research Fellow, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1852802022-09-05T12:21:46Z2022-09-05T12:21:46ZSleeping fish? From sharks to salmon, guppies to groupers, here’s how they grab a snooze<figure><img src="https://images.theconversation.com/files/476388/original/file-20220727-1332-1i5lq6.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5181%2C3423&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A large group of yellowfin tuna swimming off the coast of Italy. Like all fish, they sleep, but it's not like human sleep.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/tuna-school-royalty-free-image/607337981">Giordano Cipriani/The Image Bank via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Could you explain how fish sleep? Do they drift away on currents, or do they anchor themselves to a particular location when they sleep? – Laure and Neeraj, New York</strong> </p>
</blockquote>
<hr>
<p>From the goldfish in your aquarium to a bass in a lake to the sharks in the sea – <a href="https://web.uri.edu/gso/news/learning-from-fish-to-spark-innovation-in-ocean-exploration/">35,000 species of fish are alive today</a>, more than 3 trillion of them. </p>
<p>All over the world, they swim in hot springs, rivers, ponds and puddles. They glide through freshwater and saltwater. They survive in the shallows and in the darkest depths of the ocean, more than five miles down.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="With its unusual look -- a pancake with wings -- a stingray swims in the ocean." src="https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476397/original/file-20220727-1345-clf6b9.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">Stingrays are a type of fish too, but they are boneless.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-stingray-swimming-in-sea-royalty-free-image/1283034201?adppopup=true">Xiáng Zhèng/EyeEm via Getty Images</a></span>
</figcaption>
</figure>
<h2>Just like you, fish need to sleep</h2>
<p>Of those trillions of fish, three major types exist: <a href="https://www.thoughtco.com/what-is-a-bony-fish-2291874#:%7E:text=In%20simple%20terms%2C%20a%20bony,as%20Agnatha%2C%20or%20jawless%20fish.">bony fish</a>, like trout and sardines; jawless fish, like the slimy <a href="https://www.smithsonianmag.com/science-nature/14-fun-facts-about-hagfish-77165589/">hagfish</a>; and <a href="https://ocean.si.edu/ocean-life/sharks-rays">sharks and rays</a>, which are boneless – instead, they have skeletons made of <a href="https://theconversation.com/why-do-humans-have-bones-instead-of-cartilage-like-sharks-170526">firm yet flexible tissue called cartilage</a>.</p>
<p>And all of them, every last one, needs to rest. Whether you’re a human or a haddock, sleep is essential. It gives a body time to repair itself, and a brain a chance to reset and declutter. </p>
<p><a href="https://case.fiu.edu/about/directory/profiles/heithaus-michael.html">As a marine biologist</a>, I’ve always wondered how fish can rest. After all, in any body of water, predators are all over the place, lurking around, ready to eat them. But somehow they manage, like <a href="https://askabiologist.asu.edu/plosable/who-needs-sleep-anyway">virtually all creatures on Earth</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/B_hxMs-oHro?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">See the mysterious spot off the coast of Mexico where sharks take a nap.</span></figcaption>
</figure>
<h2>How they do it</h2>
<p>Scientists are still learning about how fish sleep. What we do know: Their sleep <a href="https://animals.howstuffworks.com/fish/do-fish-sleep.htm">is not like ours</a>. </p>
<p>For one thing, people are pretty much out of it when they sleep. While a loud noise might wake you up, you’re mostly unaware of your surroundings. But fish stay aware enough to detect an approaching predator – at least most of the time. </p>
<p>It does appear that most fish have sleep cycles like us. Aquarium fish sleep between <a href="https://whypetfish.com/how-many-hours-do-fish-sleep-a-day/">seven to 12 hours each day</a>. Many fish are active <a href="https://www.aqueon.com/articles/fish-sleeping-habits#:%7E:text=Scientists%20believe%20that%20most%20fish,in%20a%20cave%20or%20crevice.">during daylight and sleep at night</a>, though for some, like numerous types of eels, rays and sharks, it’s the reverse. </p>
<p>How can you tell if a fish is asleep? Most fish don’t have eyelids, so their eyes don’t close. That alone makes it hard to tell when they’re resting. </p>
<p>But if you watch fish in an aquarium, look closely. You’ll see how they stop swimming around and remain very still, sort of hovering in the water. Their gills will pump less too. For fish, that’s sleeping. </p>
<h2>Sleeping with the enemy</h2>
<p>Where do fish sleep? Sometimes right out in the open. But often they’re at or near the bottom. If they can, they squeeze in a spot near rocks or plants so predators can’t get them and currents can’t sweep them away. </p>
<p>Some fish go even further. Parrotfish <a href="https://www.nature.org/en-us/get-involved/how-to-help/animals-we-protect/parrotfish/">wrap a cocoon of mucus</a> around themselves and sleep in the coral. Sounds like a lot of effort – essentially, making your own sleeping bag every night – but the cocoon protects the parrotfish not just from predators,
but from parasites. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/wtf5AXfMhQQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Night security for a parrotfish: a cocoon of mucus.</span></figcaption>
</figure>
<h2>How sharks sleep</h2>
<p>There are, however, many species of fish that must swim constantly just to breathe. Think about that – stop swimming, and you die. This is true for many sharks, like <a href="https://kids.nationalgeographic.com/animals/fish/facts/great-white-shark">great whites</a>. </p>
<p>So how do they sleep if they’re always on the move? Instead of stopping altogether, sharks simply slow their swimming, or swim into a current. That’s sort of like sleep – at least the sharks seem less aware of what’s going on around them.</p>
<p>There are species of shark, like the draughtsboard shark, that <a href="https://www.smithsonianmag.com/smart-news/sharks-apparently-do-sleep-even-with-their-eyes-wide-open-180979707/">breathe without swimming</a>. Scientists recently observed this shark – which is 3 feet (1 meter) long and has a flat head – sleeping on the bottom. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/B7ePdi1McMo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A shark taking a nap?</span></figcaption>
</figure>
<h2>Whales and dolphins</h2>
<p><a href="https://us.whales.org/whales-dolphins/">Whales and dolphins</a> are not fish – they’re mammals, like cats, dogs and people. They spend their lives in the ocean, but they can’t breathe underwater. Instead, they periodically rise to the surface and take in air through their blowhole, which is on the top of their heads. </p>
<p>If they went into a deep sleep, the way people do, whales and dolphins would drown; they wouldn’t be aware enough to come to the surface to breathe. So they sleep by <a href="https://us.whales.org/whales-dolphins/how-do-dolphins-sleep/#:%7E:text=When%20sleeping%2C%20dolphins%20often%20rest,to%20the%20surface%20to%20breath.">resting one half of their brain at a time</a>. The other half remembers to rise to the surface, breathe and stay just alert enough to spot danger. </p>
<p>Is it possible that some fish might do the same thing? Scientists are trying to find out, but still don’t know. There is so much more to learn about how fish sleep. Marine biologists like me have many questions, and we spend our careers in oceans, rivers, lakes and laboratories trying to find answers. But I’ll leave you with this, something I’ve always wondered about: Do fish dream? </p>
<hr>
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<p class="fine-print"><em><span>Michael Heithaus does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Just about every creature on Earth needs to grab some Zs from time to time. Imagine trying to doze while dodging great whites and killer whales.Michael Heithaus, Executive Dean of the College of Arts, Sciences & Education and Professor of Biological Sciences, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1883322022-08-23T12:24:02Z2022-08-23T12:24:02ZDolphins use signature whistles to represent other dolphins – similarly to how humans use names<figure><img src="https://images.theconversation.com/files/479186/original/file-20220815-11-q79gbl.jpg?ixlib=rb-1.1.0&rect=120%2C699%2C4365%2C2869&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bottlenose dolphins are extremely social animals that communicate constantly.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/dolphins-underwater-royalty-free-image/89619678?adppopup=true">Micha Pawlitzki/Corbis Documentary via Getty Images</a></span></figcaption></figure><p>Bottlenose dolphins’ signature whistles just passed an important test in animal psychology. A new study by my colleagues and me has shown that these animals may use their whistles as namelike concepts.</p>
<p>By presenting urine and the sounds of signature whistles to dolphins, my colleagues <a href="https://scholar.google.com/citations?user=KhKIWqcAAAAJ&hl=en&oi=ao">Vincent Janik</a>, <a href="https://scholar.google.com/citations?user=LdOMUTYAAAAJ&hl=en&oi=ao">Sam Walmsey</a> and <a href="https://scholar.google.com/citations?user=Z9Z9u2EAAAAJ&hl=en&oi=ao">I</a> recently showed that these whistles <a href="https://doi.org/10.1126/sciadv.abm7684">act as representations of the individuals who own them</a>, similar to human names. For behavioral biologists like us, this is an incredibly exciting result. It is the first time this type of representational naming has been found in any other animal aside from humans.</p>
<h2>The meaning of a name</h2>
<p>When you hear your friend’s name, you probably picture their face. Likewise, when you smell a friend’s perfume, that can also elicit an image of the friend. This is because humans build mental pictures of each other using more than just one sense. All of the different information from your senses that is associated with a person converges to form a mental representation of that individual - a name with a face, a smell and many other sensory characteristics.</p>
<p>Within the <a href="https://doi.org/10.1080/09524622.1997.9753352">first few months of life</a>, dolphins invent their own specific identity calls – called <a href="https://doi.org/10.1038/207434a0">signature whistles</a>. Dolphins often announce their location to or greet other individuals in a pod by sending out their own signature whistles. But researchers have not known if, when a dolphin hears the signature whistle of a dolphin they are familiar with, they actively picture the calling individual. My colleagues and I were interested in determining if dolphin calls are representational in the same way human names invoke many thoughts of an individual.</p>
<p><audio preload="metadata" controls="controls" data-duration="1" data-image="" data-title="Dolphins use signature whistles to identify themselves." data-size="32290" data-source="Jason Bruck" data-source-url="" data-license="CC BY-ND" data-license-url="http://creativecommons.org/licenses/by-nd/4.0/">
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Dolphins use signature whistles to identify themselves.
<span class="attribution"><span class="source">Jason Bruck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a><span class="download"><span>31.5 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/2569/dolphin-1-signature-whistle.m4a">(download)</a></span></span>
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<p><audio preload="metadata" controls="controls" data-duration="1" data-image="" data-title="No two signature whistles are the same." data-size="47219" data-source="Jason Bruck" data-source-url="" data-license="CC BY-ND" data-license-url="http://creativecommons.org/licenses/by-nd/4.0/">
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<div class="audio-player-caption">
No two signature whistles are the same.
<span class="attribution"><span class="source">Jason Bruck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a><span class="download"><span>46.1 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/2570/dolphin-2-signature-whistle.m4a">(download)</a></span></span>
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<p>Because <a href="https://www.elsevier.com/books/anatomy-of-dolphins/cozzi/978-0-12-407229-9">dolphins cannot smell</a>, they rely principally on signature whistles to identify each other in the ocean. Dolphins can also copy another dolphin’s whistles as a <a href="https://doi.org/10.1073/pnas.1304459110">way to address each other</a>.</p>
<p>My previous research showed that dolphins have great memory for <a href="https://doi.org/10.1098/rspb.2013.1726">each other’s whistles</a>, but scientists argued that a dolphin might hear a whistle, know it sounds familiar, but <a href="https://doi.org/10.1038/nature.2013.13519">not remember who</a> the whistle belongs to. My colleagues and I wanted to determine if dolphins could associate signature whistles with the specific owner of that whistle. This would address whether or not dolphins remember and hold representations of other dolphins in their minds.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person standing next to a dolphin holding a vial of urine." src="https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479189/original/file-20220815-19-iv7nt8.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&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 researchers found that dolphins can identify each other by swimming through and tasting urine, the liquid in the syringe in this photo.</span>
<span class="attribution"><span class="source">Dolphin Quest</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Urine as an identifier</h2>
<p>The first thing my colleagues and I needed to do was find another sense that dolphins use to identify each other. In the 1980s and 1990s, researchers studying spinner dolphins in Hawaii noticed that the dolphins were occasionally <a href="https://www.ucpress.edu/book/9780520082083/the-hawaiian-spinner-dolphin">swimming through each other’s urine</a> and feces with their mouths open. Using these observations as a springboard, my colleagues and I decided to test if dolphins were able to identify each other from urine.</p>
<p>We began by first collecting urine from dolphins under managed care and simply pouring small amounts of it into lagoons where the dolphins live. The dolphins immediately showed interest, and with little training, quickly began to follow the research team anytime we carried poles with cups filled with urine. When we poured urine into the water, the dolphins would open their mouths and swim through the urine plume.</p>
<p>Our team then got urine from dolphins at other facilities to see if the subjects could differentiate between familiar and unfamiliar urine. The dolphins spent more than twice the amount of time with their mouths open tasting familiar urine compared to unfamiliar urine, providing the first evidence that <a href="https://doi.org/10.1126/sciadv.abm7684">dolphins can identify other individuals by taste</a>. </p>
<p>With this, my colleagues and I had what we needed to test representation in signature whistles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person with a long pole leading a dolphin towards a speaker" src="https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479191/original/file-20220815-11-9s4ix2.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">By pairing urine samples – in the cup at the end of the pole – with the sounds of signature whistles played from an underwater speaker, it was possible to test whether dolphins would recognize if the urine and a whistle were from the same individual.</span>
<span class="attribution"><span class="source">Dolphin Quest</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Pairing urine and whistles</h2>
<p><a href="https://doi.org/10.1016/j.pneurobio.2007.10.005">Previous studies in children</a> have successfully used multiple senses to show that pre-linguistic infants can form conceptual representations of people. My colleagues and I used this type of work as a theoretical basis for our second experiment.</p>
<p>In our experiment, the team first led a dolphin to a speaker before pouring a small amount of urine into the water. After the dolphin tasted the urine, we quickly played the sound of another dolphin’s signature whistle. Sometimes that whistle would be from the same individual as the pee sample. Other times the urine and whistle would not match. The goal was to test if the dolphins react differently if the urine and whistle were from the same dolphin compared with if the urine and whistle were from two different dolphins. If there was a consistent difference in how long the dolphins hovered close to the speaker in the matched or unmatched scenarios, it would indicate the dolphins <a href="https://doi.org/10.1073/pnas.1008169108">knew and recognized when a whistle and urine sample</a> were from the same individual – the same way a person might connect the name of a friend to that friend’s favorite perfume</p>
<p>We found that, on average, when the urine and whistle matched, dolphins spent about 30 seconds investigating the speaker. When there was a mismatch, they <a href="https://doi.org/10.1126/sciadv.abm7684">only stuck around for about 20 seconds</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A person collecting data while a dolphin swims behind him." src="https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479190/original/file-20220815-485-6v7b4b.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">When dolphins were presented with matching urine and whistles, they hovered near the speaker longer than when the samples were not from the same individual.</span>
<span class="attribution"><span class="source">Dolphin Quest</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The fact that the dolphins consistently reacted more strongly to matches than mismatches indicates that they understand which whistles correspond with which urine. This uses the same framework as other studies that use matching sensory information to <a href="https://doi.org/10.1073/pnas.1008169108">demonstrate that animals have mental representations of individuals</a>.</p>
<p>But what makes dolphins different is that they aren’t just matching physical qualities – face with a smell, for example. They are doing this with signature whistles they invent themselves. Just as you can hear a name and imagine a face with all the associated memories, dolphins can hear a signature whistle and match the urine cue. </p>
<h2>Dolphin language?</h2>
<p>This work demonstrates that dolphins have self-created signals that are representational, just as humans have invented names that are representational. Representation opens the possibility that dolphins could theoretically make third-dolphin references – where two dolphins that are communicating refer to a third dolphin that is not in the immediate vicinity. If dolphins can refer to dolphins that aren’t around them presently, this would be similar to the mental time travel a person does when speaking about a friend they haven’t seen in years.</p>
<p>Signature whistles represent the most language-like aspect of dolphin communication currently known. However, the scientific community knows little about <a href="https://doi.org/10.1006/anbe.1998.0881">dolphin non-signature calls</a> or the functions of their <a href="https://www.researchgate.net/publication/255649978_High-Frequency_Burst-Pulse_Sounds_in_AgonisticAggressive_Interactions_in_Bottlenose_Dolphins_Tursiops_truncatus">other acoustic signals</a>. With further research into how dolphins communicate with sound – as well as with chemicals – it may be possible to better understand the minds of these mammals.</p><img src="https://counter.theconversation.com/content/188332/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Bruck does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Using urine and signature whistles from other dolphins, a team of scientists has shown that dolphins use signature whistles like names and hold mental representations of other dolphins in their minds.Jason Bruck, Assistant Professor of Biology, Stephen F. Austin State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1799722022-04-12T13:53:59Z2022-04-12T13:53:59ZAfrica’s large aquatic animals are being hunted and traded: we assessed the scale<figure><img src="https://images.theconversation.com/files/456105/original/file-20220404-17-r60f66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hawksbill turtle.</span> <span class="attribution"><span class="source">Photo by Jonas Gratzer/LightRocket via GettyImages</span></span></figcaption></figure><p>Across most of the world, and particularly in the tropics and subtropics, large wild aquatic animals – such as manatees, turtles and dolphins – are being hunted and traded. This is not a new phenomenon. Aquatic animal meat has been eaten, and sometimes used as remedies or in traditional ceremonies, throughout history.</p>
<p>This type of consumption is widespread. In some places this wild meat is an important source of nutrition, income, and cultural identity. Yet opportunities to exploit wildlife for economic gain – often illegally – increase the number of animals hunted in some places. Coupled with growing human populations, this has led to the unsustainable exploitation of some species. </p>
<p>Understanding the scope and potential threat of aquatic wild meat exploitation is an important first step toward appropriate conservation actions and policies.</p>
<p>We’re part of a large international team of conservation researchers and practitioners that <a href="https://www.frontiersin.org/files/Articles/837447/fmars-09-837447-HTML/image_m/fmars-09-837447-t001.jpg">recently published</a> a paper on this. We carried out a literature review on the use of large aquatic animals (excluding fish) – what we call “aquatic megafauna” – for wild meat in the global tropics and subtropics. This topic is hugely under-researched, so this review represents one of the most in-depth assessments of the topic to date.</p>
<p>We focused on 37 species of conservation concern that are <a href="https://www.frontiersin.org/files/Articles/837447/fmars-09-837447-HTML/image_m/fmars-09-837447-t001.jpg">listed</a> on the Appendices of the Convention on the <a href="https://www.cms.int/">Conservation of Migratory Species</a> of Wild Animals. The list includes several species of whales, dolphins, and porpoises (cetaceans), manatees and dugongs (sirenians), marine turtles (chelonians), and crocodiles (crocodylians).</p>
<p>Twelve of these species inhabit oceans and rivers in West, Central and Eastern Africa. These are regions that were in the tropics and subtropics and are where there are concerns about hunting, consumption and trade.</p>
<p><a href="https://www.frontiersin.org/articles/10.3389/fmars.2022.837447/full">We found that</a> the consumption of these aquatic animals is widespread in coastal regions, to varying degrees. Some species are likely to be at risk from over-exploitation, particularly species inhabiting rivers and freshwater areas. </p>
<p>For most of the species monitored, a major issue is that animals are unintentionally caught as bycatch during fishing. They’re then opportunistically killed and eaten or sold, instead of being released when alive.</p>
<h2>Dolphins, manatees and turtles</h2>
<p>We found evidence of the use of cetaceans (whales, dolphins and porpoises) in most countries in tropical Africa, particularly in West Africa. Their meat was used for a variety of purposes including food, shark bait, and traditional medicine. </p>
<p>One species considered to be particularly at risk is the Atlantic humpback dolphin (<em>Sousa teuszii</em>). Distributed solely along Africa’s Atlantic coast, it’s one of the least understood coastal dolphins in the world. Because it has such a <a href="https://journals.co.za/doi/epdf/10.10520/EJC18185">small population size</a> and lives close to shores – where it can get captured by small-scale fishers – it’s highly vulnerable. </p>
<p>African manatees (<em>Trichechus senegalensis</em>), distributed exclusively in West and Central Africa, and dugong (<em>Dugong dugon</em>), whose range spans into East Africa, are legally protected in nearly all countries in which they occur. However, the team found evidence that they were being used for various purposes including food and traditional medicine to some degree in all countries. Most manatee populations cannot withstand human-induced mortality because their populations are <a href="https://researchonline.jcu.edu.au/19751/">highly sensitive</a> to changes in adult survival. In recent years, high losses to populations of African manatees have been reported.</p>
<p>Turtles face a similar threat. The capture and consumption of marine turtle adults, and harvest of their eggs, is ubiquitous across much of the species’ ranges. This includes mainland Africa and the African islands. However, as with the other aquatic megafauna, larger-scale monitoring is needed to assess impacts and sustainability.</p>
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<img alt="" src="https://images.theconversation.com/files/454357/original/file-20220325-25-1qczted.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454357/original/file-20220325-25-1qczted.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=312&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454357/original/file-20220325-25-1qczted.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=312&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454357/original/file-20220325-25-1qczted.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=312&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454357/original/file-20220325-25-1qczted.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=392&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454357/original/file-20220325-25-1qczted.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=392&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454357/original/file-20220325-25-1qczted.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=392&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">(A) Atlantic humpback dolphin (Sousa teuszii), Conkouati-Douli National Park, Republic of the Congo; (B) African Manatee (Trichechus senegalensis), Lagos Lagoon, Nigeria; and (C) Green turtle (Chelonia mydas), Joal, Senegal. Photo credits: Tim Collins/Wildlife Conservation Society (A), Christogonus Uzoma Ejimadu (B), and Pearson McGovern, African Aquatic Conservation Fund (C). Author provided, no reuse.</span>
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<h2>River animals</h2>
<p>Risks to riverine megafauna – those living in rivers – from harvest may be particularly high, even if opportunistic, because these species face multiple threats in the same restricted area. The threats include dams, intensive fishing, and pollution where human population density is high. In Africa, this is true of African manatees and freshwater turtles (which were not assessed in the study, but are widely hunted). </p>
<p>Riverine megafauna may suffer from a lack of management and research, and will require increased conservation efforts. This is because they’re neither seen as terrestrial species nor as fish, so it’s not often clear at the national level who is responsible for their conservation and management.</p>
<h2>Widespread</h2>
<p>Across the tropics and subtropics, there are clearly differences in local circumstances between areas. The drivers of hunting and consumption, hunting technologies used, human density and other threats to animals and their habitats, and how they change over time, will influence harvest sustainability.</p>
<p>Nonetheless, it’s clear that the use of aquatic megafauna for meat is likely to be far more widespread in terms of frequency and species than reported in the review. This is because monitoring and reporting is limited. Also because many of the species are protected by national laws, or are charismatic, so their use is secretive. </p>
<p>The trans-boundary nature of harvests and associated trade of these oceanic, coastal, and riverine species requires increased international attention and cooperation.</p><img src="https://counter.theconversation.com/content/179972/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel J Ingram was partially supported to complete this work by funding from the U.S. Fish and Wildlife Service. He is affiliated with the African Aquatic Conservation Fund.</span></em></p><p class="fine-print"><em><span>Heidrun Frisch-Nwakanma 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 of Africa’s large aquatic animals, such as dolphins, manatees and turtles, are being killed for meat.Daniel J Ingram, Researcher in Conservation, University of StirlingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1758962022-04-11T15:17:56Z2022-04-11T15:17:56ZAllow me to introduce myself: Squirrels use rattle calls to identify themselves<figure><img src="https://images.theconversation.com/files/457413/original/file-20220411-16-h30zck.jpg?ixlib=rb-1.1.0&rect=21%2C0%2C4655%2C3120&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Squirrel rattle calls may be a form of announcing their presence.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>As a scientist who studies squirrel behaviour, one of the most common questions I am asked is: “How do I get them out of my yard?”</p>
<p>It’s not as easy being a squirrel as you might think. They live a <a href="https://doi.org/10.1139/z95-133">relatively solitary life</a> guarding hard-won food stores to survive the tough winters here in Canada. The behaviour that my students and I are most interested in is how these squirrels use sounds, or what we refer to as vocal communication, to help them make it through this tough life.</p>
<h2>Solitary creatures</h2>
<p>The North American red squirrel lives a somewhat solitary life. They spend most of their days in a 50-100 metre territory foraging for pine cones and other food sources like berries and mushrooms. </p>
<p>Individuals spend time gathering cones throughout the summer and fall months, storing them in a central location called a midden. They can be rather protective of these middens, as squirrels are known to <a href="https://doi.org/10.1644/1545-1542(2005)086%3C0108:FPILRS%3E2.0.CO;2">steal a great deal from each other</a>. In fact, a squirrel can steal up to 90 per cent of its stores from neighbouring squirrels. </p>
<p>These little thieves run back and forth moving and stealing cones to survive the tough Canadian winters. While they are stealing and storing, <a href="https://www.jstor.org/stable/4534898">squirrels often produce a loud call</a>, termed a rattle. I am keenly interested in this call — my students and I watch and record squirrels to understand what these rattles might be communicating. </p>
<p>Historically it was assumed that this rattle call was produced to make sure that squirrels knew to stay out of each other’s territories — in a sense, a warning that if you enter you may encounter some aggression from the squirrel that lives there. My research has been exploring <a href="https://shannonmdigweed.weebly.com/squirrel-speak-and-pika-puns">a slightly different view of this call</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/IMOQv1QHxSQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Recordings of various red squirrel vocal communications.</span></figcaption>
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<h2>Neighbours and strangers</h2>
<p>It is possible that the call still warns other squirrels to stay out, but its <a href="https://doi.org/10.1093/czoolo/58.5.758">primary function is to identify the caller to all those who are listening</a>. As a squirrel moves through its own territory, and the territories of its neighbours, they produce intermittent rattle calls. These calls are <a href="https://www.jstor.org/stable/20799540">an announcement of who and where that squirrel is</a>. Listeners then know where their various neighbours are throughout the day. This knowledge can help mitigate costly aggressive interactions, chases and fights. </p>
<p>In addition, by communicating who is calling, the rattle can signal to listeners who is more likely to steal from you and <a href="https://doi.org/10.1016/j.anbehav.2017.08.024">thus a more threatening neighbour</a>. Some neighbours may be more likely to steal from you than others. </p>
<p>In behavioural ecology, this is referred to as <a href="https://doi.org/10.1006/anbe.1994.1047">the “dear enemy” effect</a>, and supposes that in maintaining a territory it is useful to know the relative threat posed by your neighbours versus the threat posed by strangers. In most cases, a known neighbour is far less of a threat than a stranger. </p>
<p>With red squirrels, it has been shown that <a href="https://doi.org/10.1016/j.anbehav.2017.08.024">different neighbours do have different levels of threat</a>. As a result, knowing who your neighbour is by their rattle call reveals the relative threat they represent and therefore the necessary response.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4684%2C3113&q=45&auto=format&w=1000&fit=clip"><img alt="a young red squirrel carries a pine cone" src="https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4684%2C3113&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457043/original/file-20220408-11-ggugy7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Squirrels lead solitary lives.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<h2>Social calls</h2>
<p>Self-announcement or self-identification is a common vocal behaviour across many different species. Several marine mammal species, <a href="https://doi.org/10.1073/pnas.0509918103">such as dolphins</a> <a href="https://doi.org/10.1016/j.beproc.2008.04.007">and seals</a>, also produce calls that contain information about who is calling. They are used to identify social companions and offspring. </p>
<p>Several species of primates also have calls that contain information about who is calling. Again, these are often used in social interactions to help mitigate aggression during foraging — <a href="https://doi.org/10.1006/anbe.1998.1031">baboons</a> and <a href="https://doi.org/10.1002/ajp.20398">capuchin monkeys</a>, for example. So it’s not unusual that a species like the red squirrel would also have information about who is calling to help them with difficult territory interactions. </p>
<p>My students and I have found that squirrels produce these calls throughout their territory as well as in the territory of close neighbours. By conducting experiments on when and where the squirrels produce the rattle call, we hope to show that the occurrence of this call is about announcing who and where you are, and not strictly about getting others out of your territory.</p><img src="https://counter.theconversation.com/content/175896/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shannon M. Digweed 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>North American red squirrels produce a range of sounds, but their distinctive rattle call may have more to do with identifying themselves than warning off other squirrels.Shannon M. Digweed, Associate professor, Psychology and Biological Sciences, MacEwan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1795412022-03-25T13:48:16Z2022-03-25T13:48:16ZWe’ve discovered why some whales stop feeding in response to the sound of sonar<p>In September 2002, a number of beaked whales were stranded and killed in the Canary Islands during a <a href="https://www.theguardian.com/world/2002/sep/28/animalwelfare.nato">NATO naval exercise</a>. It was the first time we started to get a real understanding of the negative <a href="https://www.researchgate.net/publication/228346496_Beaked_Whale_Strandings_and_Naval_Exercises">effects of sonar sounds</a> on cetaceans, which includes whales, dolphins and porpoises.</p>
<p>But why did the noise of sonar seem to affect beaked whales in particular, rather than other species of cetacean?</p>
<p>In our <a href="https://www.pnas.org/doi/full/10.1073/pnas.2114932119">new research</a>, we’ve discovered that the response of each species to predators could explain why some whales and dolphins are more sensitive to this human-made noise.</p>
<p>It was back in the early 2000s that we (along with other researchers around the world) began to study the <a href="https://www.int-res.com/abstracts/esr/v31/p293-315/">impact of sonar</a> on free-ranging whales. These new “behavioural responses studies” exposed different cetacean species to gradually increasing levels of sonar – with careful monitoring to keep the animals from harm. We were then able to identify the level of sonar noise at which behavioural changes began to occur. </p>
<p>From that early research we knew that feeding is commonly affected when marine mammals are disturbed by sonar, and some species are markedly more sensitive to this exposure than others. For example, <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2013.0223">Cuvier’s beaked whales</a> showed dramatically more severe changes in their feeding habits (swimming rapidly and silently away while extending their length of dive and non-feeding period) than <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2013.0657">blue whales</a>. </p>
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Read more:
<a href="https://theconversation.com/are-marine-protected-areas-helping-marine-mammals-and-birds-maybe-but-more-can-be-done-173045">Are marine protected areas helping marine mammals and birds? Maybe, but more can be done</a>
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<p>But until now the reasons for this differing response between species <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.12955">were unclear</a>. So, we decided to investigate whether they were responding to human-made sound in <a href="https://www.ecologyandsociety.org/vol6/iss1/art11/">a similar way</a> to their response to predators, as some theories suggested. </p>
<h2>Exposing whales to sound</h2>
<p>Most cetaceans are themselves the prey of another cetacean, the <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2907.1991.tb00291.x">killer whale</a>. Some species, including beluga and beaked whales, have few defence mechanisms. But others are safer due to their large body size, like sperm whales, or large social groups, such as pilot whales.</p>
<p>This means that different species respond differently to the presence of killer whales. We set out to discover whether four cetacean species respond to navy sonar in the same way they respond to the sounds of predatory killer whales – and whether differences across the species related to their natural level of risk from these fearsome predators.</p>
<p>By tagging the animals with <a href="https://ieeexplore.ieee.org/document/1190131">suction-cupped recording devices</a> – which capture the timing of both sound and movement – we were able to monitor the feeding and movement of 43 tagged whales off the coast of Norway: three toothed whale species (northern bottlenose, sperm and long-finned pilot) and one baleen whale species (humpback). </p>
<p>We measured their reduction in feeding time when exposed to naval sonar – varying from one to four kilohertz – and compared it to their response to recordings of predatory killer whale sounds. </p>
<h2>Links to predator threat</h2>
<p>We found that both naval sonar and the predator sounds caused a clear reduction in feeding time across the four whale species. By contrast feeding activity was unaffected when we exposed them to the sounds of sea vessels without sonar or other control sounds.</p>
<p>Strikingly, each species responded similarly to sonar and predatory sounds: northern bottlenose whales had the strongest response and ceased foraging for food entirely (100% loss of feeding time), followed by humpback whales and long-finned pilot whales (both approximately 75%). Sperm whales had the lowest response, reducing time spent feeding by approximately 50% to both sounds.</p>
<p>It’s clear that the different hearing sensitivity of each species is not sufficient to explain the observed difference – that’s because the humpback whales, which have the best hearing in the frequency band of the sonar, were not the most sensitive. </p>
<p>Instead our findings indicate that risk from killer whales plays a role in driving the responses, and that adaptations to their predators can explain cetacean sensitivity to human-made noise.</p>
<p>The northern bottlenose whales, who rely on crypsis (staying hidden) and flight to reduce their risk of death by killer whale, were very cautious and gave up feeding when detecting sounds of potential threats – but the species that are less vulnerable to predation were also less responsive to sounds of killer whales and sonar.</p>
<h2>Implications for Arctic whales</h2>
<p>Our findings can help to predict which cetaceans are likely to have extreme responses to human generated ocean noise – and help us to set appropriate conservation priorities.</p>
<p>The findings are particularly relevant to cetacean species in the Arctic as they are at highest risk of predation.</p>
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Read more:
<a href="https://theconversation.com/killer-whales-taking-food-from-fishing-lines-reveal-something-intriguing-about-human-evolution-176050">Killer whales taking food from fishing lines reveal something intriguing about human evolution</a>
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<p>For example, Narwhal behaviour and distribution is influenced by <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1611707114">Arctic killer whales</a> and, as we would expect, they are sensitive to <a href="https://www.frontiersin.org/articles/10.3389/fmars.2021.658173/full?fbclid=IwAR1UYzZw4AP7vOgzcqzQ3kpLaAuF83pCGbphddeV8rRzmeprMPlYOPtDNjU">human-made sounds</a> such as airgun pulses and ship noise.</p>
<p>As sea ice rapidly decreases, Arctic cetaceans face a double whammy of impacts – increasing levels of predation from more killer whale movements into ice-free zones, as well as increasing levels of noise from human activities, such as seismic exploration, military and shipping. </p>
<p>As well as the risk of immediate injury or death, it will be important to consider the effects of human disturbance on their feeding and other behaviours.</p><img src="https://counter.theconversation.com/content/179541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>I was a member of the team that received funding from various navy sponsors to study the effects of sonar on cetaceans.
The research was carried out independently from sponsor influence, and our publication policy states: "...under no circumstances can sponsors claim the right to influence the scientific analysis, interpretation and publication of original data in a binding way." The polluter therefore appropriately paid for this research, but had no influence on the conduct or publication of the research. </span></em></p><p class="fine-print"><em><span>As with Patrick Miller.</span></em></p><p class="fine-print"><em><span>As with Patrick Miller</span></em></p>Whale species at higher risk of predation from killer whales are more adversely affected by the sound of sonar.Patrick Miller, Professor of Biology, University of St AndrewsCharlotte Cure, Researcher in Bioacoustics, UMRAE, FranceSaana Isojunno, Research fellow, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1730452021-12-16T11:09:04Z2021-12-16T11:09:04ZAre marine protected areas helping marine mammals and birds? Maybe, but more can be done<p>Our oceans are under pressure like never before, <a href="https://ipbes.net/sites/default/files/inline/files/ipbes_global_assessment_report_summary_for_policymakers.pdf">with over 60%</a> struggling from the increasing impact of fishing, coastal activities and climate change. The harsh truth is that as we move towards 2022 only 3% of oceans are totally free from the pressure of human activity. The greatest impact appears to be on large-bodied animals such as marine mammals and birds, which cannot reproduce as quickly as smaller species.</p>
<p>Through my 40 years of extensive work on marine animals - and my current involvement in a European Commission project to help assess the effectiveness of marine protection areas (MPAs) - I have come to understand some of the issues which we need to consider to ensure that MPAs protect marine biodiversity.</p>
<p>Over one-third of marine mammals are <a href="http://assets.wwf.org.uk/downloads/living_blue_planet_report_2015.pdf">threatened with extinction</a> – and in Europe over 30% of <a href="https://www.birdlife.org/wp-content/uploads/2021/10/BirdLife-European-Red-List-of-Birds-2021.pdf">marine birds</a> are declining. Some species, including the Balearic shearwater and Atlantic puffin, are already endangered.</p>
<p>MPAs have been established to limit or exclude human activities that could potentially harm species and habitats. And, after a slow start, the last ten years have seen encouraging progress. MPAs now cover the 2020 global <a href="https://static1.squarespace.com/static/5c77fa240b77bd5a7ff401e5/t/60a506dac996a914d3d0970e/1621427930222/Embargoed+Facts+Figues+PP_14052021.pdf">target of 10% of oceans</a>, while some seas with high levels of human activity (the North Sea for example) have reached as much as <a href="https://www.eea.europa.eu/publications/marine-protected-areas">27% MPA coverage</a>. </p>
<p>At a <a href="https://www.cbd.int/cop/">recent meeting</a>, the international community agreed to <a href="https://www.gov.uk/government/topical-events/global-ocean-alliance-30by30-initiative/about">protect 30% of oceans</a> through MPAs and other conservation measures by 2030.</p>
<p>So, can we be optimistic that MPAs can turn the tide of declining marine biodiversity? Well, maybe, but in those ten years between 2010 and 2020 many species have continued to struggle despite the marked increase in MPAs. I would argue that more can be done to help marine mammals and birds specifically. Here’s some of my reasoning.</p>
<h2>Size could be an issue</h2>
<p>For one thing, I consider that the protected areas are probably too small to be fully effective – 50% of MPAs in EU waters <a href="https://www.eea.europa.eu/themes/water/europes-seas-and-coasts/assessments/marine-protected-areas">measure less than 30km²</a> and most are below 5km². This is a particular problem for marine mammals and birds, which are among the most mobile of all animals. I am not just talking about the annual 80,000km <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2836663/">global migration of the Arctic tern</a> between the Arctic and Southern Ocean, or the 22,000km <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2015.0071">migratory movements of the gray whale</a> in the Pacific – many other marine species are <a href="https://www.researchgate.net/publication/51242840_Tracking_apex_marine_predator_movements_in_a_dynamic_ocean">extremely mobile</a> too.</p>
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Read more:
<a href="https://theconversation.com/expanding-marine-protected-areas-by-5-could-boost-fish-yields-by-20-but-theres-a-catch-148678">Expanding marine protected areas by 5% could boost fish yields by 20% – but there's a catch</a>
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<p>Even diminutive harbour porpoises can <a href="https://www.researchgate.net/publication/324350987_Oceanic_movements_site_fidelity_and_deep_diving_in_harbour_porpoises_from_Greenland_show_limited_behavioural_similarities_to_North_Sea_harbour_porpoise_population">move great distances</a>, and have been tracked by satellite travelling more than 2,000km from Greenland’s west coast out into the North Atlantic west of Ireland.</p>
<p>Some seabirds, such as gannets, can often show a <a href="https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1890/14-1300.1">strong preference for particular locations</a> and return to these year after year. There are also populations within a species, coastal bottlenose dolphins for example, which are much more sedentary and <a href="https://academic.oup.com/jhered/article/104/6/765/799365">tied to a particular location</a>. So, MPAs can be helpful in those cases. But the long distance migratory habits of many marine species shows the importance of providing protections throughout their life cycle and not only when they are in an MPA.</p>
<p>Within the European Union (EU) special protection areas for seabirds tend to be concentrated around the breeding colony, with little of the rest of the marine area protected. Yet, <a href="https://www.sciencedirect.com/science/article/pii/S0006320711004721?via%3Dihub">seabird species</a> may regularly forage tens, sometimes hundreds, of kilometres away to find food for their young. I feel that the pressure of commercial fishing activity – due to depletion of fish stocks offshore - is rarely incorporated adequately in management plans.</p>
<p>Currently, marine mammal biodiversity does not seem to be well addressed by the EU habitats directive, because only six of the 30 species which regularly inhabit or pass through its waters are placed in a <a href="https://ec.europa.eu/environment/nature/natura2000/sites_hab/index_en.htm">special annex</a> requiring protected sites. Many more need area-based protection, including minke whale, killer whale and several dolphin species.</p>
<h2>What next?</h2>
<p>The creation of an MPA, particularly a coastal one, can bring its own challenges. Marine mammals and birds are iconic, and attract a lot of public interest. </p>
<p>The pressure of human disturbance may actually increase once the site has become designated and publicised. It flags that there are interesting species to be found, and suddenly the animals become the focus of attention. This is an increasing <a href="https://www.wcl.org.uk/docs/WCL_Wildlife_Crime_Report_Nov_21.pdf">problem in the UK</a>, fuelled by the rise in tourist trips to view the resident mammals and birds.</p>
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Read more:
<a href="https://theconversation.com/the-hopeful-return-of-polar-whales-151487">The hopeful return of polar whales</a>
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<p>Many marine protected areas lack management plans, but in my opinion even those that have them rarely implement management in a fully effective way. Regulations may curtail human activities within the MPA but they rarely stop them entirely. And in many cases the activity, be it a wind farm construction or disturbance to the <a href="https://www.theguardian.com/environment/georgemonbiot/2015/nov/09/allowing-scallop-dredging-in-strictly-protected-dolphin-reserves-is-madness">seabed from fishing</a>, can often take precedence for socio-economic reasons.</p>
<p>Management plans, where they exist, often simply describe the problematic human activities. I think that there is limited consideration given to the impact of those pressures on different species, and robust monitoring of their populations is mostly inadequate. </p>
<p>How can anyone tell whether management measures are effective if neither the species nor the human activity is fully monitored, and the links between activity and its impact on each species has not been established? It seems to me that the <a href="https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/marine-protected-areas-and-marine-spatial-planning-for-the-benefit-of-marine-mammals/CB1EAB762D102DC951C12D9E1B46562F">bar for effective management</a> of MPAs needs to be raised substantially from where it is at present. </p>
<p>European or other regional conservation agreements to <a href="https://www.ascobans.org">help highly mobile cetaceans</a> can help to improve the situation. That’s not to say that joining them automatically protects marine mammals – it does not. But it is a move in the right direction, and focuses governments to work together to protect these much-cherished species by better understanding and addressing specific threats.</p>
<p>So, spare a thought for the Atlantic puffin in its nesting burrow and the bottlenose dolphin mother and calf in their shallow bay. Would they recognise in a positive way that they are living and breeding in a marine protected area?</p><img src="https://counter.theconversation.com/content/173045/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Evans receives funding from UNEP/ASCOBANS to coordinate a conservation action plan for the harbour porpoise; he is currently part of a project funded by the European Commission to develop a questionnaire for member states to assess the management effectiveness of MPAs; and on occasions has had funding from Natural Resources Wales to monitor bottlenose dolphin and harbour porpoise populations within Special Areas of Conservation in West Wales. </span></em></p>There are some important issues to consider to best help marine species such as Atlantic puffins, bottlenose dolphins and orcas.Peter Evans, Honorary Senior Lecturer, Director of Sea Watch Foundation, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1679872021-10-19T03:21:02Z2021-10-19T03:21:02ZThe critically endangered Māui dolphin is a conservation priority – we shouldn’t let uncertainty stop action to save it<figure><img src="https://images.theconversation.com/files/424833/original/file-20211005-15-1jwu5eo.JPG?ixlib=rb-1.1.0&rect=25%2C271%2C2419%2C1356&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">University of Auckland Department of Conservation</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The world’s rarest marine dolphin, <a href="https://www.doc.govt.nz/nature/native-animals/marine-mammals/dolphins/maui-dolphin/">Māui</a>, is found only along the west coast of the North Island of Aotearoa New Zealand. </p>
<p>Based on our surveys over the last two summers, during which we collected small tissue samples for DNA analysis, we estimate there are currently only <a href="https://www.doc.govt.nz/globalassets/documents/conservation/native-animals/marine-mammals/maui-hectors-dolphins/maui-abundance/maui-dolphin-abundance-2021.pdf">54 Māui dolphins over one year of age</a>. </p>
<p>These estimates are similar to previous surveys carried out over the past decade, since the establishment of the <a href="https://www.doc.govt.nz/nature/habitats/marine/other-marine-protection/west-coast-north-island/">West Coast North Island Marine Mammal Sanctuary</a> in 2008, which restricts or regulates the use of setnets, trawling and drift nets within 12 nautical miles of most of the west coast.</p>
<p>The prevailing narrative remains that fisheries pose by far the most significant threat, but we argue it is time to act on other causes of death, including the parasite that causes toxoplasmosis, a disease that starts in cats. </p>
<p>Māui dolphins are a genetically distinct subspecies, separated by about 15,000 years from the closely related Hector’s dolphin. They look identical but Māui dolphins are found only along the west coast of the North Island and are <a href="https://www.doc.govt.nz/nature/native-animals/marine-mammals/dolphins/maui-dolphin/">critically endangered</a>, while Hector’s are mainly found around the South Island.</p>
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<p>Historically, there were several hundred Māui dolphins, but numbers declined rapidly from the 1970s, largely because they were being caught in fishing nets. Despite warnings during the 1980s and 1990s about the unsustainable number of deaths, there was initially a lack of urgency to address this threat. </p>
<p>We now risk repeating history by ignoring other known threats. </p>
<p><audio preload="metadata" controls="controls" data-duration="20" data-image="" data-title="Listen to Māui clicks" data-size="160529" data-source="Department of Conservation" data-source-url="https://www.doc.govt.nz/globalassets/documents/conservation/native-animals/marine-mammals/maui-hectors-dolphins/maui-recording.mp3" data-license="CC BY-ND" data-license-url="http://creativecommons.org/licenses/by-nd/4.0/">
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Listen to Māui clicks.
<span class="attribution"><a class="source" rel="nofollow" href="https://www.doc.govt.nz/globalassets/documents/conservation/native-animals/marine-mammals/maui-hectors-dolphins/maui-recording.mp3">Department of Conservation</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a><span class="download"><span>157 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/2298/maui-recording.mp3">(download)</a></span></span>
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<h2>Dolphin deaths from toxoplasmosis</h2>
<p>We know toxoplasmosis kills Māui dolphins, but the greatest challenge in determining the exact cause of death is finding their bodies. Some wash ashore, but with so few dolphins spread over a sparsely inhabited, rugged coastline, only a small percentage are found. Many are too decomposed to determine their cause of death. </p>
<p>Post-mortems show they die from “natural” causes such as old age, disease and shark predation, but also from human-related factors, including toxoplasmosis. </p>
<p>Researchers <a href="https://www.sciencedirect.com/science/article/abs/pii/S0304401712005675">found</a> over half of the dead Māui and Hector’s dolphins examined were infected with the parasite that causes toxoplasmosis. Of the ten Māui dolphins found dead since 2006, two had died of toxoplasmosis. </p>
<p>This parasite completes its life cycle inside a cat, producing millions of eggs that enter the environment in cat poo. These eggs are extremely resistant. They can survive hot, cold, dry and wet conditions, including in seawater, for at least a year. </p>
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<strong>
Read more:
<a href="https://theconversation.com/toxoplasma-cat-poo-parasite-infects-billions-so-why-is-it-so-hard-to-study-120688">Toxoplasma 'cat poo' parasite infects billions – so why is it so hard to study?</a>
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<p>The eggs enter the sea in freshwater runoff, where they are eaten by fish, shellfish and crabs. Māui dolphins are most likely infected by eating fish that have consumed the parasite eggs. Once inside a dolphin, the parasite multiplies and can cause death. </p>
<p>Toxoplasmosis also kills native birds and can cause disease in humans.</p>
<p>The fact that cats can indirectly kill dolphins is difficult for many people to comprehend, leading some to discount this as a serious threat. While the overall impact of toxoplasmosis is currently unclear, ultimately this is a human-caused threat which should be openly discussed, as has happened for fisheries threats. </p>
<p>We believe the current focus on fisheries bycatch, to the exclusion of all other threats, puts Māui dolphins at risk of further decline.</p>
<h2>Repeating history</h2>
<p>There is considerable uncertainty around this threat, but we do know Māui dolphins die of toxoplasmosis and this disease causes population-level impacts on other species of marine mammals, including sea otters and Hawaiian monk seals. </p>
<p>In terms of action, we’ve been here before: lack of certainty around Māui dolphin bycatch deaths in the 1980s and 1990s meant that the threat from fisheries was largely ignored, with the loss of more dolphins. </p>
<p>We risk repeating history if we again <a href="https://www.doc.govt.nz/nature/pests-and-threats/diseases/toxoplasmosis-and-hectors-and-maui-dolphin/toxoplasmosis-action-plan/">ignore the known threat of toxoplasmosis</a> because we are unable to have courageous conversations about managing the risk to the few remaining Māui dolphins.</p>
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<p>We believe the fisheries risk, while not entirely eliminated, has largely been controlled. However, because of the exclusive focus on fisheries from some sectors, New Zealand is at the centre of a <a href="https://www.newsroom.co.nz/nz-government-joins-us-lawsuit-on-seafood-ban">US lawsuit to ban our fish imports</a>.</p>
<p>This lawsuit claims there is insufficient protection from bycatch. It is based on unsupported information about Māui dolphin distribution. If the lawsuit is successful, it could cost New Zealand up to NZ$200 million. </p>
<p>Considering the Māui dolphin’s status and the financial risk to New Zealand, the government seems slow to support open discussion, research and actions to manage poorly understood risks, including disease. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/study-identifies-nine-research-priorities-to-better-understand-nzs-vast-marine-area-119547">Study identifies nine research priorities to better understand NZ's vast marine area</a>
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<p>Millions of research dollars are spent on terrestrial species that have less urgent immediate conservation needs and less reputational risk to Aotearoa. The Māui dolphin is our most urgent conservation priority, and we face challenging decisions. </p>
<p>If we are to learn anything from the lack of action to manage fisheries threats when they were first identified, it is that we should not let uncertainty stop us from acting to manage other threats to Māui dolphins.</p><img src="https://counter.theconversation.com/content/167987/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rochelle Constantine receives funding from the Department of Conservation – Te Papa Atawhai and Fisheries New Zealand – Tini a Tangaroa. She is affiliated with MAUI63. </span></em></p><p class="fine-print"><em><span>Wendi Roe 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>Māui dolphins are at risk of extinction. With a marine mammal sanctuary in place since 2008, the risk from fisheries is now largely under control. It’s time to take other threats more seriously.Rochelle Constantine, Associate Professor of Marine Biology, University of Auckland, Waipapa Taumata RauWendi Roe, Professor, Massey UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1591412021-04-28T20:06:59Z2021-04-28T20:06:59ZMammals’ brains: new research shows bigger doesn’t always mean smarter<figure><img src="https://images.theconversation.com/files/397292/original/file-20210427-21-vgtopa.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1280%2C417&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Javier Lazaro/www.lazaroillustration.com</span></span></figcaption></figure><p>If a friend boasts of having a “big-brained” dog, your reaction is probably not to ask “relative to what?”. You would simply assume your friend thinks their dog is pretty smart. But are we always right to equate big brains with greater intelligence?</p>
<p>In a study <a href="https://advances.sciencemag.org/content/7/18/eabe2101">published today in Science Advances</a>, we and our colleagues describe how the relationship between large brains and “intelligence” in mammalian evolution isn’t as straightforward as you might assume.</p>
<p>A key problem is that, in evolutionary terms, a “large brain” doesn’t just refer to the absolute size of the brain. Rather, we refer to mammals as big-brained when their brain volume is large relative to their body mass.</p>
<p>There are many examples of intelligent animals that are also large-brained for their size. Humans are a particularly extreme case; our brains are roughly seven times larger than expected for an animal of our size. Dogs are also famously large-brained and smart, as are whales, dolphins and elephants. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scatter plot of brain size relative to body size" src="https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=508&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=508&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=508&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=638&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=638&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397485/original/file-20210428-23-1dtmwd3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=638&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Brain to body size plot highlighting humans and hominins (species ancestral to humans) in red, dolphins in black, other toothed whales in grey, bears in blue, and seals and sea lions in purple.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This big-equals-smart equivalence has also been applied in research on mammalian brain size evolution, under the assumption that relatively large mammalian brains evolve in situations where natural selection favours greater intelligence. But what if it’s not brain size that became larger, but body size that became smaller?</p>
<p>To investigate this question, we assembled the largest data set of brain and body masses of mammals from the existing literature. In total, we compiled size data for 1,400 mammal species, including 107 fossils. </p>
<p>We then assembled an evolutionary tree for these species. This allowed us to ask how brain and body size have related to each other throughout the evolution of mammals, starting from before the extinction of dinosaurs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Evolutionary tree of mammals and brain sizes" src="https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=557&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=557&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=557&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=700&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=700&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397288/original/file-20210427-21-1yjgpwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=700&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Evolutionary tree of mammals - different colours represent groups of species that share a similar brain-to-body size relationship.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our analysis revealed a mixed bag of evolutionary trajectories in brain and body sizes. For example, elephants are large, large-brained, and also known to be very intelligent. We saw that this combination arose through the elephants undergoing an even greater increase in brain size than expected for their large body size.</p>
<p>In contrast, the evolutionary lineages for humans and dolphins – both among the largest-brained mammals on Earth - were particularly unique in having larger brains but smaller bodies compared with their close relatives (chimps and gorillas for humans; other toothed whales for dolphins). This unusual combination makes their brains spectacularly large among mammals.</p>
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<p>
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<strong>
Read more:
<a href="https://theconversation.com/curious-kids-which-is-smarter-a-blue-whale-or-an-orca-122789">Curious Kids: which is smarter – a blue whale or an orca?</a>
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<p>Strikingly, some mammals that are known to be very intelligent underwent stronger natural selection on body size than on brain size. The California sea lion, for example, famous for its circus-trick smarts, has an unusually small brain relative to its body mass. This is because when the evolutionary ancestors of seals and sea lions began living in water, evolution favoured massive increases in body size — perhaps to conserve body heat, to ward off predators such as sharks, or more generally because gravity is less of an impediment to large body size in water than in air.</p>
<p>This means California sea lions’ relative brain size is much smaller than expected, given their intelligence. So how are they so smart? One possible explanation is that, despite their relatively smaller brain size compared with their close relatives, California sea lions have up to four times more volume dedicated to brain areas that support intelligent behaviour, such as learning complicated tricks.</p>
<p>This seems to make them much smarter than other mammals with comparable brain sizes, such as bears, and shows why sea lions can learn skills that are not in their innate repertoire of behaviours, such as making vocalisations on command.</p>
<h2>Evolutionary upheavals</h2>
<p>Our analysis also revealed that cataclysmic events in evolutionary history left their hallmarks in mammals’ brains. For example, there was an acceleration in increases in brain size relative to body mass after the extinction of the dinosaurs 66 million years ago. We think this may be due to the fact many mammals found new habitats to live in that were previously occupied by dinosaurs, often requiring new adaptations in either brain or body size. </p>
<p>Another intriguing pattern is a substantial rearrangement of the relationship between brain and body sizes between 30 million and 23 million years ago, when Earth cooled rapidly and some big evolutionary changes (such as the evolution of seals and sea lions) happened.</p>
<p>Some of these changes left legacies that still endure today. They have resulted in some of the biggest (elephants and whales) and smallest (bats and shrews) mammal brains on Earth.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/brain-versus-brawn-the-evolution-of-humans-and-other-animals-27910">Brain versus brawn: the evolution of humans and other animals</a>
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<p>Given that the evolution of brain size and intelligence is even more complex than we realised, how do we go about trying to understand it more fully? We definitely need to consider the evolutionary background of present-day mammals. However, it is also important to understand how the various parts of the brain evolve relative to one another. </p>
<p>For example, humans and dolphins not only have large brains overall, but also an astoundingly large neocortex, which is the powerhouse of mammal intelligence.</p>
<p>In the meantime, next time your friend boasts about their big-brained dog, remind them size isn’t everything.</p><img src="https://counter.theconversation.com/content/159141/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vera Weisbecker receives funding from The Australian Research Council. </span></em></p><p class="fine-print"><em><span>Jeroen Smaers receives funding from The US National Science Foundation. </span></em></p>Some animals, such as California sea lions, have small brains relative to their body size, but are still impressively intelligent, showing brain evolution is even more complex than it appears.Vera Weisbecker, Associate Professor, Flinders UniversityJeroen Smaers, Associate professor, Stony Brook University (The State University of New York)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1585342021-04-07T15:38:24Z2021-04-07T15:38:24ZWe discovered that whale and dolphin brains produce lots of heat. Why it matters<figure><img src="https://images.theconversation.com/files/393741/original/file-20210407-21-1m642x5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A humpback whale near the Antarctic ice.</span> <span class="attribution"><span class="source">Dr Olga Shpak </span></span></figcaption></figure><p>We have all heard the mantra that dolphins and whales (cetaceans) are highly intelligent animals. Some claim they’re on par with great apes and humans – maybe even smarter. But where does this concept come from? </p>
<p>There are two lines of thought. Firstly, a range of cetacean behaviours are <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1469-185X.2008.00049.x">interpreted</a> as displays of notable intelligence. Second, cetaceans have very <a href="https://www.karger.com/Article/Abstract/454797">large brains</a>; several species have brains that weigh more than human brains. We have large brains, and it is the structure and activity within these large brains that determines our abilities to examine, analyse and manipulate the world in a very complex way. So it has been thought that any other animal that has a brain as large, or larger, must be using their brain for the same thing. </p>
<p>But this logic is based on a very specific assumption: that 1 gram of brain tissue has, on average, the same capacity to process information in the same way irrespective of the brain in which it is found. It is this assumption that I have <a href="https://onlinelibrary.wiley.com/doi/abs/10.1017/S1464793106007019">questioned over the past 20 years</a> and I have come to a very different conclusion.</p>
<p>In my most <a href="https://www.nature.com/articles/s41598-021-84762-0">recent study</a>, my colleagues and I have ascertained that the cetacean brain is indeed special. Not for intelligence, though: it is special because it produces a lot more heat than the brains of other mammals. Through our research we’ve concluded that the cetacean brain has a specialised thermogenic system. It helps the animal’s brain to produce enough heat to maintain a functional brain temperature, and we believe this will combat the loss of heat to the water. This is separate to the special way whales and dolphins <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0116734">keep their bodies warm</a>.</p>
<p>Evidence suggests the neurothermogenic specialisation we describe evolved around 32 million years ago.</p>
<p>With this knowledge, scientists can better understand how important water temperature is to the survival of cetaceans. This, in turn, will allow us to understand what will happen to certain species of cetaceans during the <a href="https://science.sciencemag.org/content/363/6423/128.summary">inevitable rise in oceanic temperatures</a> associated with anthropogenic-induced climate change.</p>
<p>It is quite possible that some species, such as those dependent on the polar ice, like narwhals and beluga whales, may become victims of global warming. This new understanding of cetaceans will allow us to direct our conservation efforts in the most appropriate way to secure the future of as many species of cetacean as possible.</p>
<h2>Size and skill</h2>
<p>Compared to humans – and indeed many other mammals – cetacean brains have a very small <a href="https://onlinelibrary.wiley.com/doi/abs/10.1017/S1464793106007019">prefrontal cortex</a> (that part involved in our higher mental/executive activities), a tiny <a href="https://link.springer.com/article/10.1007/s00429-013-0660-1">hippocampus</a> (responsible for memory formation/retrieval and spatial navigation), and many other features that are very different to other mammals.</p>
<p>This means we can conclude that the structure of the cetacean brain does not endow them with the “hardware” necessary for the production of behaviours that are more complex than those seen in many other animals, unlike humans.</p>
<p>So, if the cetacean brain is not large for intellectual purposes, why is it so big? </p>
<p>Cetacean brains became truly large <a href="https://onlinelibrary.wiley.com/doi/abs/10.1017/S1464793106007019">around 32 million years ago</a>, about 20 million years after they became fully aquatic mammals. At this time, there was a <a href="https://science.sciencemag.org/content/292/5517/686">major cooling</a> of global oceanic temperatures. This coincided with the loss of the shallow, warm, nutrient-rich, equatorial <a href="https://www.britannica.com/topic/Neo-Tethys-Sea">Tethys sea</a>. These ancient cetaceans were faced with a quandary: adapt to this new, cold, open ocean environment, or become extinct.</p>
<p>The mammalian brain produces its own heat, independent of the body, to maintain a stable temperature of 37°C. Even a small drop in brain temperature leads to a reduction in neural activity. Cetaceans mostly live in oceanic waters; the mammalian body loses heat via conductive heat transfer to the water <a href="https://www.nature.com/articles/335675b0">90 times faster</a> than to air at the same temperatures; and mammal brains need to be maintained at 37°C. Given these factors, I proposed that perhaps the environmental pressure of colder water occurring around 32 million years ago was the trigger for the evolution of the larger brain in cetaceans.</p>
<h2>Inside the cetacean brain</h2>
<p>To provide support to this idea, my colleagues and I examined the heat-producing system within the brains of cetaceans and their close relatives the artiodactyls – such as hippopotamuses, pigs, antelopes, buffaloes and giraffes. </p>
<p>We reasoned that this heat-producing system would have to use the process of <a href="https://jeb.biologists.org/content/214/2/242">non-shivering thermogenesis</a>, a way to produce heat within cells rather than through muscular activity, as there are no muscles surrounding the brain. The most commonly studied part of the body that produces heat through non-shivering thermogenesis is <a href="https://www.mayoclinic.org/healthy-lifestyle/weight-loss/expert-answers/brown-fat/faq-20058388">brown fat</a>. Brown fat cells can change their internal metabolic pathways so as to produce heat, warming up the body. This happens when mitochondria (organelles within the cell that produce energy) change their activity so that rather than producing adenosine triphosphate (ATP), for chemical energy in the cell, they produce heat. This is achieved by activating uncoupling proteins (UCPs). </p>
<p>In the cetacean brain we found that almost three times as many neurons contain these proteins compared to their terrestrial relatives. We also found that between 30 and 70% of glial cells contain UCPs in cetaceans, while in artiodactyls the glial cells did not contain UCPs in readily detectable amounts. Glial cells are the housekeepers of the brain: they maintain the right micro-environment to support active neuronal functioning.</p>
<p>We conclude that the cetacean brain has a specialised thermogenic system that emerged around 32 million years ago. This, we believe, will combat the loss of heat to the water – and help cetaceans to maintain a functional brain temperature.</p>
<h2>A special brain</h2>
<p>So, yes: the cetacean brain is special, as long believed. But this brain isn’t used for special intellectual functions and complex thoughts. Instead, it’s special because it produces a lot more heat than the brains of other mammals, and this is necessary for their survival in the colder aquatic environment they inhabit.</p><img src="https://counter.theconversation.com/content/158534/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Manger receives funding from the National Research Foundation of South Africa. </span></em></p>The cetacean brain has a specialised thermogenic system that helps the animal’s brain to produce enough heat to maintain a functional brain temperature.Paul Manger, Professor of Comparative and Evolutionary Neurobiology, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1469622020-10-02T13:56:04Z2020-10-02T13:56:04Z500 whales stranded in Tasmania – indigenous elders are best guides to understanding this tragedy<p>Close to 500 pilot whales beached themselves in September 2020, in what has been described as Australia’s <a href="https://www.firstpost.com/world/380-pilot-whales-dead-in-largest-mass-stranding-ever-recorded-in-australia-nearly-500-still-stranded-in-tasmania-8847071.html#:%7E:text=Hobart%3A%20More%20pilot%20whales%20were,ever%20recorded%20in%20the%20country.">biggest mass stranding</a> on record. Rescue efforts <a href="https://www.nytimes.com/2020/09/26/world/australia/tasmania-beached-whales.html">saved</a> 108 of the marine mammals, which belong to the dolphin family, but <a href="https://institutions.newscientist.com/article/dn4428-predator-theory-for-whale-mass-stranding/">scientific attempts</a> to explain the tragedy have so far offered only theories, including sickness, navigational errors, and sudden changes in the tide.</p>
<p>Indigenous peoples throughout the Pacific, including the Maori of Aotearoa (New Zealand), have been <a href="https://www.theguardian.com/environment/2019/jan/03/what-is-the-sea-telling-us-maori-tribes-fearful-over-whale-strandings">raising the alarm</a> for some time. For generations, people here have watched the movements of these whales closely to help them navigate the world’s largest ocean. </p>
<p>For the Aboriginal people of Australia and indigenous communities throughout the Pacific, changes in whale behaviour are ominous. With a rich oral history to draw from, the indigenous people of the Pacific are among our best guides for making sense of the recent strandings, and the wider environmental changes they portend.</p>
<h2>Ocean giants in Pacific folklore</h2>
<p>The slipstreams of whales and dolphins weave throughout the folklore of the Pacific Islands. The Maori tell the story of Paikea who, when faced with drowning due to the machinations of his evil brother, recited an incantation and summoned a whale to save himself. </p>
<p>The seaways between the Central Carolines and the Marianas would chant of Ikelap – “the big fish” – when it was sighted by voyagers. It was a signpost that the journey was nearing the east coast of Guam. Western mariners would come to know this big fish as the pilot whale – a namesake that speaks to it being a dependable guide.</p>
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<img alt="A black long-finned pilot whale mother swims with her grey calf close behind." src="https://images.theconversation.com/files/361368/original/file-20201002-17-1qiawbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/361368/original/file-20201002-17-1qiawbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/361368/original/file-20201002-17-1qiawbr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/361368/original/file-20201002-17-1qiawbr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/361368/original/file-20201002-17-1qiawbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/361368/original/file-20201002-17-1qiawbr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/361368/original/file-20201002-17-1qiawbr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Ancient voyagers tracked pilot whales in order to help navigate the Pacific Ocean.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/long-finned-pilot-whale-mother-calf-565369348">Andrew Sutton/Shutterstock</a></span>
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<p>It’s a common belief among many different Pacific communities that whales and dolphins are spirit transformations or carriers of ancestors. As such, whales are often sought for spiritual guidance to <a href="https://www.doc.govt.nz/about-us/science-publications/conservation-publications/native-animals/marine-mammals/conservation-of-whales-in-the-21st-century/whaling-and-new-zealand/the-indigenous-relationship-with-whales-in-new-zealand/">decide</a> where to settle and when to avoid fishing or sailing. </p>
<p>Changes in whale migratory routes, songs and unusual surfacing behaviour are all instructive, and observations of distressed whales – to a degree that’s far outside the norm – are interpreted as significant omens. In Tikopia, part of the Solomon Islands, the stranding of whales signified imminent spiritual danger.</p>
<p>Since their whaling rights are protected under the International Whaling Commission, indigenous catch reports have also been used to help <a href="https://iwc.int/humpback-whale">track whale populations</a> and to identify when commercial whaling was depleting populations in the past.</p>
<p>Indigenous accounts are invaluable as they provide a reliable, long-term record of how whale populations have changed over time according to changes in their environment.</p>
<h2>What the whales foretold</h2>
<p>Environmental change in the Pacific is not new. Oral history recalls when, at the end of the last ice age, <em>fenua imi</em> (an island-eating demon), swallowed the land and forced the migration of its peoples across Oceania. The history of the Pacific is a history of migration, and the whales and dolphins have accompanied these movements, guiding voyagers across the vast ocean. </p>
<p>Climate change could be considered the modern return of <em>fenua imi</em>. But it comes with additional barriers. Political and legal borders now restrict the free movement of people across the Pacific, even as climate change threatens to inundate these vulnerable islands with storms, rising tides and the destruction of vital habitat such as mangroves and coral reefs. </p>
<p>While much international attention has focused on what sea level rise will mean for the low-lying lands of the Pacific, deep changes within the oceans are just as urgent. One of the North Pacific’s <a href="https://theconversation.com/worst-marine-heatwave-on-record-killed-one-million-seabirds-in-north-pacific-ocean-129842">worst marine heatwaves</a> on record killed one million seabirds between the summer of 2015 and the spring of 2016. Hotspots of marine biodiversity are threatened by <a href="https://theconversation.com/galapagos-how-to-protect-the-islands-amazing-marine-life-from-huge-chinese-fishing-fleets-144927">overfishing</a> and <a href="https://theconversation.com/deep-sea-mining-threatens-indigenous-culture-in-papua-new-guinea-112012">deep-sea mining</a>. And while many people have heard of the <a href="https://theconversation.com/uk/topics/great-pacific-garbage-patch-46255">Great Pacific Garbage Patch</a>, fewer know about the poisons that this <a href="https://theconversation.com/plastic-poisons-ocean-bacteria-that-produce-10-of-the-worlds-oxygen-and-prop-up-the-marine-food-chain-117493">floating plastic waste</a> produces, killing microorganisms that produce oxygen and feed marine life. The recent whale strandings, historic in scale, are a reminder that problems in the biosphere cannot be treated in isolation.</p>
<p>Listening to indigenous communities throughout the Pacific about environmental change is not only important, but it is also vital in our attempts to correct the damage done to marine ecosystems.</p><img src="https://counter.theconversation.com/content/146962/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Niki JP Alsford 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>It’s time to listen to warnings from the people of the Pacific.Niki JP Alsford, Professor in Asia Pacific Studies, Director of the Asia Pacific Studies Institutes, University of Central LancashireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1466742020-09-23T04:35:21Z2020-09-23T04:35:21Z‘Like trying to find the door in a dark room while hearing your relatives scream for help’: Tasmania’s whale stranding tragedy explained<p>A desperate rescue effort is underway after hundreds of long-finned pilot whales (<em>Globicephala melas</em>) became stranded in Macquarie Harbour on Tasmania’s west coast. </p>
<p>Yesterday, more than 250 pilot whales <a href="https://www.bbc.com/news/world-australia-54244499">were reported</a> to have stranded, with one-third presumed dead. And this morning, rescuers found <a href="https://www.sbs.com.au/news/another-200-pilot-whales-found-stranded-on-tasmania-s-remote-west-coast">another 200 pilot whales</a> stranded up to ten kilometres away from the first group — most are likely dead. </p>
<p>This brings the total number of stranded pilot whales in Tasmania to more than 450, and it’s believed to be the biggest ever recorded in the state. The Greens are calling on federal Environment Minister Sussan Ley to launch a national response.</p>
<p>The rescue mission aims to refloat the pilot whales that appear to still be in reasonable health. But their behaviour hampers rescue efforts: many pilot whales re-strand themselves to be with their family. This event likely means a number of generations of the local population will be lost.</p>
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<a href="https://theconversation.com/do-whales-attempt-suicide-50165">Do whales attempt suicide?</a>
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<h2>How did they become stranded?</h2>
<p>Despite its name, the long-finned pilot whale is actually a large oceanic dolphin. They cover <a href="https://oceana.org/marine-life/marine-mammals/long-finned-pilot-whale">vast areas</a> of the Southern (Antarctic) Ocean, reaching between four and six metres in length and weighing up to one tonne. </p>
<p>They are well adapted to deeper oceans where <a href="https://www.nature.com/articles/s41598-019-51619-6">they hunt</a> for various species of squid in depths of between 600-1,000m, using echolocation to find their prey. Echolocation is a way of using sound to navigate in complete darkness. </p>
<p>They generally spend most of their lives offshore and it’s not well understood what conditions drive them close to shore, and to enter shallow embayments. </p>
<p>Some theories suggest food shortages are to blame, or changes in electromagnetic fields that disorient them. They may also be following a sick or distressed pod leader. And <a href="https://www.smh.com.au/environment/conservation/strong-association-found-between-whale-strandings-and-use-of-naval-sonar-20200219-p5428a.html.">in some past cases</a> strandings were related back to active sonar from ships and naval sonar interrupting their echolocation. </p>
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<a href="https://theconversation.com/what-causes-whale-mass-strandings-72985">What causes whale mass strandings?</a>
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<p>But once in shallow waters, it’s difficult to swim back out. As these whales mostly navigate with echolocation it’s not possible for them to use sonar effectively in shallow and muddy embayments. </p>
<p>It’s extremely distressing for the whales, a lot like trying to find the door in a dark room while hearing your relatives scream for help. </p>
<p>In fact, the stress is what many die from in the end. Other causes of death are overheating from sun exposure and drowning if they can’t move their bodies up to breach the surface in shallow water. </p>
<h2>The rescue efforts</h2>
<p>There are a <a href="https://www.bbc.com/news/world-asia-38939799">number of strategies</a> to refloat whales. In Macquarie Harbour, rescuers are using slings to tow the whales to deeper water, before releasing them. </p>
<p><a href="https://www.stuff.co.nz/nelson-mail/news/89265113/mass-whale-stranding-at-farewell-spit">Other options</a> include multiple people pushing them off the beach during high tide into deeper water. </p>
<p>In this case, albeit potentially dangerous for the helpers, people power can make a big difference. After all, time is of immense importance for success, and to stop more whales beaching. </p>
<p>However, chances of survival plummet with long exposure to sun and extended periods of stress. What’s more, Macquarie Harbour is relatively remote and difficult to access, further complicating rescue efforts. </p>
<h2>Dying together</h2>
<p>But the biggest obstacle rescuers face is the whales’ social bonding. Long-finned pilot whales are highly intelligent and live in <a href="https://brill.com/view/journals/beh/154/5/article-p509_1.xml">strong social units</a>. </p>
<p>So when dealing with mass strandings, it’s important to realise the emotions and bonding between the whales are very likely beyond what humans can feel. One well-documented example of their emotional depth is the pilot whale seen <a href="https://www.youtube.com/watch?v=0a8HGJid-Jo">carrying its dead calf</a> for many days.</p>
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<figcaption><span class="caption">Mother pilot whale grieves over her dead calf.</span></figcaption>
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<p>This makes the stranding process extremely complex, as it unfolds over several hours to several days — the whales don’t all strand at the same time. </p>
<p>We know from killer whales, which also have strong social bonding, that if a close member of the group strands, <a href="https://www.abc.net.au/news/2013-07-03/stranded-killer-whales-die-off-queenslands-fraser-island/4796904">others will attempt to join</a> to <a href="https://theconversation.com/do-whales-attempt-suicide-50165">die together</a>.</p>
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Read more:
<a href="https://theconversation.com/we-need-to-understand-the-culture-of-whales-so-we-can-save-them-123884">We need to understand the culture of whales so we can save them</a>
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<p>The situation for pilot whale pods can be similar, but more complex as a result of having much larger pods. Pilot whale pods have multiple sub-units, which can consist of friends as well as family and they don’t have to be genetically related. </p>
<p>Social units get mixed up when they’re in shallow bays. This means individuals can <a href="https://www.sciencedaily.com/releases/2013/03/130314124603.htm">become disconnected</a> from their social units before the actual stranding occurs, causing stress and confusion prior the beaching. </p>
<h2>Fewer pilot whales in the gene pool</h2>
<p>There are <a href="https://www.fisheries.noaa.gov/species/long-finned-pilot-whale">an estimated</a> 200,000 long-finned pilot whales in the Southern Ocean and Antarctica, but mass strandings like this can have a profound impact on sub-populations. </p>
<p>In Tasmania alone, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0206747">1,568 long-finned pilot whales</a> have stranded between 1990 and 2008 in 30 stranding events. </p>
<p>Many similar sad events <a href="https://www.doc.govt.nz/news/media-releases/2018/mass-pilot-whale-stranding-at-rakiurastewart-island/">occured in New Zealand</a>: hundreds of long-finned pilot whales stranded in 2018 and 2017, and <a href="https://www.newscientist.com/article/2120967-400-pilot-whales-stranded-on-new-zealands-whale-trap-beach/">the majority</a> died. </p>
<p>To make matters worse, studies suggest the long-finned pilot whales in the Southeastern Pacific have low genetic diversity. There are similarities between this species found in Chile and New Zealand, but with surprisingly <a href="https://www.nature.com/articles/s41598-020-58532-3">distinct differences</a> between New Zealand and Tasmania. </p>
<p>Considering they can live up to 50 years and the fact only few survive when multiple generations strand, such events not only destroy entire generations but also remove them from the gene pool. </p>
<p>This puts local populations at further risk. Inbreeding is one consequence, but the biggest problem is their decreasing general fitness and ability to adapt to changes.</p>
<h2>How to help</h2>
<p>In the past, significant numbers of stranded whales have been successfully released, making it worth the effort. For example, in one of largest mass strandings in New Zealand in 2017, volunteers helped about 100 whales <a href="https://www.doc.govt.nz/news/media-releases/2017/whale-rescue-effort-continues/">refloat</a>, and made a human chain to try to stop them restranding. </p>
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Read more:
<a href="https://theconversation.com/its-time-to-speak-up-about-noise-pollution-in-the-oceans-64672">It's time to speak up about noise pollution in the oceans</a>
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<p>Still, such events are likely to be more frequent in the future due to changing ocean conditions and increasing human activity such a noise pollution, commercial squid fisheries and deep sea mining. </p>
<p>Climate change <a href="https://tos.org/oceanography/article/southern-ocean-warming">shifts ocean currents</a> as sea temperature rises. And with this, squid availability will change. A <a href="https://www.jstor.org/stable/24857467?seq=1#metadata_info_tab_contents">lack of food</a> offshore can cause stress and drive them closer to shore.</p>
<p>We can help the whales not only by actively supporting rescue organisations such as <a href="http://www.orrca.org.au/">ORRCA</a>, but also by helping reduce carbon emissions, foster sustainable fisheries, reduce plastic pollution and advocate for marine sanctuaries.</p><img src="https://counter.theconversation.com/content/146674/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Olaf Meynecke receives funding from a private charitable trust, and is the CEO of the not-for-profit organisation Humpbacks and Highrises. </span></em></p>More than 450 long-finned pilot whales are stranded in Tasmania. Saving them is a race against time.Olaf Meynecke, Research Fellow in Marine Science, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1379712020-07-01T12:29:43Z2020-07-01T12:29:43ZWith the help of trained dolphins, our team of researchers is building a specialized drone to help us study dolphins in the wild<figure><img src="https://images.theconversation.com/files/344347/original/file-20200626-104510-1vztssl.jpg?ixlib=rb-1.1.0&rect=8%2C8%2C1599%2C1068&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The only way to learn about the sensory abilities of dolphins is with the help of trained dolphins. </span> <span class="attribution"><span class="source">Dolphin Quest</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Human actions have taken a steep toll on whales and dolphins. Some studies estimate that small whale abundance, which includes dolphins, <a href="https://doi.org/10.3354/esr01008">has fallen 87% since 1980</a> and <a href="https://marinedebris.noaa.gov/sites/default/files/mdp_entanglement.pdf">thousands of whales die from rope entanglement</a> annually. But humans also cause less obvious harm. Researchers have found changes in the stress levels, reproductive health and respiratory health of these animals, but this valuable data is extremely hard to collect.</p>
<p>To better understand how people influence the overall health of dolphins, <a href="https://scholar.google.com/citations?user=Z9Z9u2EAAAAJ&hl=en&oi=sra">my colleagues and I</a> at Oklahoma State University’s <a href="https://ceat.okstate.edu/usri/index.html">Unmanned Systems Research Institute</a> are developing a drone to collect samples from the spray that comes from their blowholes. Using these samples, we will learn more about these animals’ health, which can aid in their conservation.</p>
<h2>The old ways vs. the new way</h2>
<p>Today, researchers wanting to measure wild dolphins’ health primarily use remote biopsy darting – where researchers use a small dart to collect a sample of tissue – or handle the animals in order to collect samples. These methods don’t physically harm the animals, but despite precautions, they can be disruptive and stressful for dolphins. Additionally, this process is challenging, time-consuming and expensive.</p>
<p>My current research focus is on <a href="https://integrativebiology.okstate.edu/8-people/faculty/449-jason-n-bruck">dolphin perception</a> – how they see, hear and sense the world. Using my experience, I am part of a team building a drone specifically designed to be an improvement over current sampling methods, both for dolphins and the researchers. Our goal is to develop a quiet drone that can fly into a dolphin’s blind spot and collect samples from the mucus that is mixed with water and air sprayed out of a dolphin’s blowhole when they exhale a breath. This is called the blow. Dolphins would experience less stress and teams could collect more samples at less expense.</p>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p>
<p>Some researchers already use <a href="https://doi.org/10.3389/fmars.2017.00425">drones to sample blows from large and small whales</a>. But those animals are not easily startled and have huge blow fields that throw droplets far into the air and linger for a long time. Dolphin blows spray seawater, air and hormone-containing mucus from their blowholes at <a href="https://doi.org/10.1242/jeb.126870">nearly 200 mph and last for about 0.3 seconds</a>. Additionally, dolphins may have <a href="https://doi.org/10.1242/jeb.053397">better hearing than humans</a> and have eyes on both sides of their head that can see in <a href="https://doi.org/10.1016/0077-7579(72)90008-7">both air and water</a>. Good luck sneaking up on a dolphin. </p>
<p>Other teams have attempted to collect samples from dolphins using commercial drones, but it seems the animals’ movements <a href="https://doi.org/10.1002/ecs2.2901">limit the success of these attempts with these devices</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=387&fit=crop&dpr=1 754w, https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=387&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/344346/original/file-20200626-104529-8ib2qi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=387&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers work with trained dolphins to learn more about their sensory abilities, seen here testing a dolphin’s hearing.</span>
<span class="attribution"><span class="source">Jason Bruck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A lot to learn from hormones</h2>
<p>When sampling the blow, we are looking for hormones in mucus as these can be used to gauge psychological and physiological health. We are specifically interested in <a href="https://dx.doi.org/10.1371%2Fjournal.pone.0114062">hormones like cortisol</a> and <a href="https://doi.org/10.1016/j.ygcen.2018.04.003">progesterone</a>, which indicate stress levels and reproductive ability respectively, but can also help determine overall health.</p>
<p>Additionally, blow samples can detect <a href="https://dx.doi.org/10.1128%2FmSystems.00119-17">respiratory pathogens</a> in the lungs or nasal passages - blowholes evolved from noses after all. </p>
<p>This health analysis is especially important in areas with oil spills as the chemicals can cause hormonal problems that harm <a href="https://www.carmmha.org/investigating-how-oil-spills-affect-dolphins-and-whales/">development, metabolism and reproduction</a> in dolphins.</p>
<p>Hormone samples can provide scientists with valuable data, but collecting them from intelligent and unpredictable animals is challenging. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=378&fit=crop&dpr=1 600w, https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=378&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=378&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=475&fit=crop&dpr=1 754w, https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=475&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/344340/original/file-20200626-104494-1vhfqx1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=475&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wild dolphins are fast, smart and can roam thousands of miles and disappear beneath the waves at a moment’s notice.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/dolphins-in-the-ocean-royalty-free-image/1210381908?adppopup=true">Borchee/E+ via Getty Images</a></span>
</figcaption>
</figure>
<h2>Cetacean collaborators</h2>
<p>To build a drone that can stealthily collect spray from moving dolphins, we needed more data on their eyesight and hearing, and this is data that couldn’t be collected in the wild nor simulated in a lab. </p>
<p>We worked with dolphins at facilities like Dolphin Quest in Bermuda, which provides guests opportunities to learn about dolphins while allowing <a href="https://dolphinquest.com/about-us/our-story/">scientists access to animals for noninvasive research</a>. Here the dolphins can swim away if they choose not to work with us, so we had to design the study like a game; the way a kindergarten teacher entertains a class. If the dolphins aren’t interested, we don’t get to do the science.</p>
<p>Over the course of hundreds of sessions, we sought to answer two questions: What can dolphins hear and what can they see around their heads? </p>
<p>To test dolphin hearing, we set up microphones and cameras to record dolphin behavior as we played drone noise in the air. We analyzed the responses to each noise – such as how many dolphins looked at the speaker – and used these as a proxy for their ability to hear the sounds. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/UjmQeH3vXHI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">To test the range of a dolphin’s vision, researchers trained the dolphin to whistle any time it saw a light turn on within the sphere. (Turn on sound to hear the dolphin whistle.) Credit: Dolphin Quest.</span></figcaption>
</figure>
<p>To test vision, we mounted lights inside a Hobermann sphere – the expandable rainbow plastic sphere you can see in the video above – that we can turn on and off. The dolphins were trained to whistle when they saw a light around their head. By turning on one light on at a time – which you can watch <a href="https://www.youtube.com/watch?v=7FAaV2Mc0uc">in this video</a> – we created a map of the dolphin’s field of view. </p>
<p>Next, we needed to understand the blow and a means to practice drone flights without a dolphin. To do this, graduate students built robodolphin, which includes a mechanical dolphin lung and replica of the blowhole.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=355&fit=crop&dpr=1 600w, https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=355&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=355&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=446&fit=crop&dpr=1 754w, https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=446&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/344325/original/file-20200626-104484-1wrzdcv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=446&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Robodolphin doesn’t look like a real dolphin, but it doesn’t need to in order to train our drone pilots.</span>
<span class="attribution"><span class="source">C.J. Barton; Oklahoma State University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To build robodolphin, we worked with dolphins trained to “chuff” or sneeze on command to measure spray characteristics. We used high-speed photography to see the dolphins’ breath as it moved through the air. Then we conducted high resolution CT scans of a dolphin head and 3D-printed a replica of a nasal passage. </p>
<p>Now, we have a complete robodolphin and are tweaking its sprays to be nearly identical to the real thing. This will allow us to determine how close we need to get to collect the samples, and therefore, how quiet our drone needs to be.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=455&fit=crop&dpr=1 600w, https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=455&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=455&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=572&fit=crop&dpr=1 754w, https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=572&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/344327/original/file-20200626-104538-1unx0q8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=572&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 replica dolphin blowhole was designed from a scan of a real blowhole passage, and the spray it produces closely matches the real thing.</span>
<span class="attribution"><span class="source">Alvin Ngo, Mitch Ford and CJ Barton; Oklahoma State University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A bit of practice, then into the wild</h2>
<p>In the next few months, we will test flights over robodolphin with existing drones to determine the timing and strategy for collection. From there, we will fabricate a low-noise drone that can fly fast enough and with sufficient maneuverability to capture samples from wild dolphins. Like a video game, we will use the visual field data to develop approach trajectories to stay in the visual blindspots. </p>
<p>We plan to test our drones on a truck-mounted robodolphin moving down a runway, then using a boat to simulate realistic conditions. The next steps will involve ocean testing with dolphins trained for open ocean swimming. These tests will determine if our devices can catch and hold the hormones as the drone flies back to a researcher’s boat.</p>
<p>Finally, we will deploy the system to collect data on wild dolphins. Our first goal is to test resident dolphins – animals that live on the coasts and deal directly with boat and oil industry noise – which will allow us to learn more about stress resulting from human impacts.</p>
<p>Those samples are a way off, but if all goes well we will have a specially built drone capable of flying long distances and capturing samples undetected in a few years. The samples collected will allow researchers to do better science with impact on the animals they study.</p><img src="https://counter.theconversation.com/content/137971/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Bruck has received conservation research funding from Dolphin Quest.</span></em></p>Wild dolphins are fast, smart and hard to study, but it is important to understand how human actions affect their health. So we are building a drone to sample hormones from the blowholes of dolphins.Jason Bruck, Teaching Assistant Professor of Integrative Biology, Oklahoma State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1325272020-03-31T14:05:01Z2020-03-31T14:05:01ZNew discovery: penguins vocalise under water when they hunt<figure><img src="https://images.theconversation.com/files/319244/original/file-20200309-118881-1i3w8wb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">King Penguins at sea.</span> <span class="attribution"><span class="source">John Dickens</span></span></figcaption></figure><p>Penguins, like all seabirds, are known to be highly vocal on land where they come to breed. They use these vocalisations to help them <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2000.1112">recognise</a> their mate and kin. </p>
<p>Outside of the breeding season, seabirds spend most of their life at sea and are adapted to the marine environment where they feed. Penguins are very unique among seabirds for their extreme diving abilities. They can perform series of dives to depths of between 20 and 500m (depending on the species) in search of fish, krill, or squid.</p>
<p>Given the penguins’ diving abilities, we wanted to know if they produced sound underwater. To do this, our Marine Apex Predator Research Unit <a href="https://mapru.mandela.ac.za">(MAPRU)</a> team at Nelson Mandela University (South Africa) attached small video loggers, with built-in microphones, on the back of three species of penguins: the King penguin, the Gentoo penguin and the Macaroni penguin.</p>
<p>Our study <a href="https://peerj.com/articles/8240/">provides</a> the first evidence that penguins emit sounds under water when they hunt.</p>
<h2>Recording penguins at sea</h2>
<p>Because of recording difficulties, very little was previously known about the vocalisations of penguins when they are at sea. However, thanks to recent developments in technology, such observation <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/ibi.12806">becomes accessible</a>, in particular through the use of miniaturised penguin-borne video loggers.</p>
<p>We used video loggers and recorded 203 underwater vocalisations from all three species over almost five hours of underwater footage: 34 from two King penguins, a single one from a Macaroni penguin and 168 from Gentoo penguins. </p>
<p>These species were chosen because they reflect the diversity of feeding strategies in penguins. The King penguin is specialised to feed on fish at a substantial depth (<a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/0012-9658%281998%29079%5B1905%3AFSOKPA%5D2.0.CO%3B2">200m</a>), whereas the Macaroni penguin feeds mostly on schooling krill within the <a href="https://link.springer.com/article/10.1007/s00300-010-0950-5">first 10m of the water column</a>. In contrast, the Gentoo penguin displays a very diverse foraging strategy, feeding on <a href="https://link.springer.com/article/10.1007/s00227-017-3113-1">all sorts of prey</a> at <a href="https://link.springer.com/article/10.1007/s00227-016-3066-9">all depths</a>.</p>
<p>The birds were caught as they left their breeding colonies at Marion Island (a sub-Antarctic island off South Africa) on the way out to the sea. We then retrieved the cameras after a single foraging trip. </p>
<p>We found that all vocalisations were short and emitted during dives when the penguin was hunting. Most vocalisations (73%) happened during the bottom phase of the dives. This is where penguins <a href="https://jeb.biologists.org/content/213/22/3874.short">mostly</a> catch their food, as opposed to the descent and ascent. </p>
<p>Here is a video showing a full dive by a King penguin, as observed from the penguin-borne video loggers:</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/2qp_51XO4ao?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>Here is a short clip showing only a few underwater vocalisations associated with prey capture:</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/024DafCNoIg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>More than 50% of the vocalisations were directly associated with a hunting behaviour: immediately after they had accelerated (<a href="https://link.springer.com/article/10.1007%2Fs00227-005-0188-x">chasing prey</a>) or immediately after an attempt at catching prey.</p>
<p>Because vocalisations were produced by all three species of penguins, it suggests that underwater vocal behaviour may exist in other penguin species. The vocalisations were also recorded in higher proportion when penguins were feeding on fish, compared to krill and squid. This suggests they could be more common in penguins that feed on fish.</p>
<h2>Unexpected?</h2>
<p>Our findings on their vocal behaviour were totally unexpected, though some of the penguin <a href="https://www.cb.universite-paris-saclay.fr/">acoustics experts</a> on our team in France had their suspicions about what we might discover.</p>
<p>We already knew that the use of vocalisations at the sea surface was related to group formation in the <a href="https://www.nationalgeographic.com/animals/birds/g/gentoo-penguin/">Gentoo penguins</a> and that African penguins vocalise from the sea surface <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/ibi.12806">mostly when</a> commuting (possibly to keep contact with one another) and foraging on bait-balls (possibly to synchronise their behaviours). </p>
<p>There is also evidence which shows that other air-breathing marine predators – such as <a href="https://link.springer.com/chapter/10.1007%2F978-1-4612-1150-1_4">dolphins</a>, <a href="https://books.google.co.za/books?hl=fr&lr=&id=McNEUgU8Q58C&oi=fnd&pg=PR9&dq=Riedman+M.+1990.+The+Pinnipeds:++Seals,+Sea+Lions,+and+Walruses.+Berkeley:+University+of+California+Press.&ots=hq3uwPw1kM&sig=Wg_UlpgzOHAYF1zJ3eriPUxU-44&redir_esc=y#v=onepage&q=Riedman%20M.%201990.%20The%20Pinnipeds%3A%20Seals%2C%20Sea%20Lions%2C%20and%20Walruses.%20Berkeley%3A%20University%20of%20California%20Press.&f=false">seals</a> and <a href="https://bioone.org/journals/Copeia/volume-105/issue-1/CE-16-407/First-Evidence-of-the-Pig-nosed-Turtle-Carettochelys-insculpta-Vocalizing/10.1643/CE-16-407.short">marine turtles</a> – produce sound under water. So why not penguins as well?</p>
<h2>Door open for future research</h2>
<p>From our observations, new questions have arisen. For example, how are penguins able to produce such sound under water, given the high pressure at depth? And why are they vocalising under water? Are all these vocalisations signalling the same information? Do they produce other underwater vocalisations in different contexts? Are they related to physiological needs for a predator diving and feeding in apnoea – to <a href="https://jeb.biologists.org/content/205/9/1189">adjust buoyancy</a>? Could they have a function in <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/ibi.12806">social interactions</a>? Could they be part of a hunting technique and be used to <a href="https://afspubs.onlinelibrary.wiley.com/doi/abs/10.1577/1548-8675%281992%29012%3C0667%3AROBHTH%3E2.3.CO%3B2">startle prey</a>? </p>
<p>We hope recent developments in technology will continue to provide more insights into the penguins’ fascinating behaviour.</p><img src="https://counter.theconversation.com/content/132527/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andréa Thiebault receives research funding from South Africa's National Research Foundation.</span></em></p><p class="fine-print"><em><span>Pierre Pistorius receives research funding from South Africa's National Research Foundation. </span></em></p><p class="fine-print"><em><span>Isabelle Charrier and Thierry Aubin do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>This study provides the first evidence that penguins emit sounds underwater when they hunt.Andréa Thiebault, Postdoctoral fellow, Nelson Mandela UniversityIsabelle Charrier, Chercheuse CNRS en bioacoustique, Université Paris-SaclayPierre Pistorius, Professor , Nelson Mandela UniversityThierry Aubin, Senior Scientist, Centre national de la recherche scientifique (CNRS)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1225382019-10-28T06:08:35Z2019-10-28T06:08:35ZWhales and dolphins found in the Great Pacific Garbage Patch for the first time<figure><img src="https://images.theconversation.com/files/297846/original/file-20191021-56238-1v6puro.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Adult and infant sperm whales have been spotted in the Great Pacific Garbage Patch.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/87328375@N06/8536963600/in/photolist-e1oaRA-8Gp7LD-59Pf77-WUXVap-7hZcak-gCTTxX-6X4huN-7CgPu8-2ab5bp-FK8fYh-qDgH7q-8mwNDu-9Zb8ag-Ww5Efs-mA1GX-amyLxb-6Rvru3-fjfSY-59Jkx4-59Jkvx-qVHuY1-BZe3h-zFVwB-fjfSN-qDbJ3b-5NPHsf-EX2Cu4-aaPyTb-reof1N-YSPPet-qEW3EA-fKNr2T-9mSaUV-fKmph3-WZEkb8-eXeHym-dhNUc3-vWhLDF-dhNK2h-dhNR7L-Zu8Mo2-h3XAEp-2BsQNe-7zCvgQ-fj9tJ-4wn122-sck8rC-qTyQiY-h3ZvBz-hKXgD">Inf-Lite Teacher/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Scientific research doesn’t usually mean being strapped in a harness by the open paratroop doors of a Vietnam-war-era Hercules plane. But that’s the situation I found myself in several years ago, the result of which has just been <a href="https://link.springer.com/article/10.1007/s12526-019-00952-0">published</a> in the journal Marine Biodiversity. </p>
<p>As part of the <a href="https://www.youtube.com/watch?v=hlIXcq2ijZQ">Ocean Cleanup’s Aerial Expedition</a>, I was coordinating a visual survey team assessing the largest accumulation of ocean plastic in the world: the Great Pacific Garbage Patch. </p>
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Read more:
<a href="https://theconversation.com/the-oceans-plastic-problem-is-closer-to-home-than-scientists-first-thought-123422">The ocean's plastic problem is closer to home than scientists first thought</a>
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<p>When the aircraft’s doors opened in front of me over the Pacific Ocean for the first time, my heart jumped into my throat. Not because I was looking 400m straight down to the wild sea below as it passed at 260km per hour, but because of what I saw. </p>
<p>This was one of the most remote regions of the Pacific Ocean, and the amount of floating plastic nets, ropes, containers and who-knows-what below was mind-boggling. </p>
<p>However, it wasn’t just debris down there. For the first time, we found proof of <a href="https://link.springer.com/article/10.1007/s12526-019-00952-0">whales and dolphins in the Great Pacific Garbage Patch</a>, which means it’s highly likely they are eating or getting tangled in the huge amount of plastic in the area. </p>
<h2>The Great Pacific Garbage Patch</h2>
<p>The Great Pacific Garbage Patch is said to be the largest accumulation of ocean plastic in the world. It is located between Hawaii and California, where huge ocean currents meet to form the North Pacific subtropical gyre. An estimated <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5864935/">80,000 tonnes of plastic</a> are floating in the Great Pacific Garbage Patch.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-major-source-of-ocean-plastic-pollution-youve-probably-never-heard-of-111687">The major source of ocean plastic pollution you've probably never heard of</a>
</strong>
</em>
</p>
<hr>
<p>Our overall project was overseen and led by The Ocean Cleanup’s founder Boyan Slat and then-chief scientist Julia Reisser. We conducted two visual survey flights, each taking an entire day to travel from San Francisco’s Moffett Airfield, survey for around two hours, and travel home. Along with our visual observations, the aircraft was fitted with a range of sensors, including a short-wave infrared imager, a Lidar system (which uses the pulse from lasers to map objects on land or at sea), and a high-resolution camera. </p>
<p>Both visual and technical surveys found whales and dolphins, including sperm and beaked whales and their young calves. This is the first direct evidence of whales and dolphins in the heart of the Great Pacific Garbage Patch.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=304&fit=crop&dpr=1 600w, https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=304&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=304&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=381&fit=crop&dpr=1 754w, https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=381&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/296602/original/file-20191011-188797-8wu2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=381&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mating green turtles in a sea of plastics.</span>
<span class="attribution"><span class="source">photo by Chandra P. Salgado Kent</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Plastics in the ocean are a growing problem for marine life. Many species can mistake plastics for food, consume them accidentally along with their prey or simply eat fish that have themselves eaten plastic. </p>
<p>Both beaked and sperm whales have been recently found with heavy plastic loads in their stomachs. In the Philippines, a <a href="https://www.bbc.com/news/world-asia-47608949">dying beaked whale</a> was found with 40kg of plastic in its stomach, and in Indonesia, a dead <a href="https://www.nationalgeographic.com/animals/mammals/s/sperm-whale/">sperm whale</a> washed ashore with 115 drinking cups, 25 plastic bags, plastic bottles, two flip-flops, and more than 1,000 pieces of string in its stomach.</p>
<h2>The danger of ghost nets</h2>
<p>The most common debris we were able to identify by eye was discarded or lost fishing nets, often called “ghost nets”. Ghost nets can drift in the ocean for years, trapping animals and causing injuries, starvation and death. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/297849/original/file-20191021-56220-k3ttsu.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">Crew sorts plastic debris collected from the Great Pacific Garbage Patch on a voyage in July 2019.</span>
<span class="attribution"><span class="source">EPA/THE OCEAN CLEANUP</span></span>
</figcaption>
</figure>
<p>Whales and dolphins are often found snared in debris. Earlier this year, a young sperm whale almost died after spending three years <a href="https://www.nationalgeographic.com/environment/2019/01/digit-sperm-whale-saved-from-rope-entanglement-ghost-net-fishing-gear-off-dominica/">tangled in a rope from a fishing net</a>. </p>
<p>During our observation we saw young calves with their mothers. Calves are especially vulnerable to becoming trapped. With the wide range of ocean plastics in the garbage patch, it is highly likely animals in the area ingest and become tangled in it.</p>
<p>It’s believed the amount of plastics in the ocean could <a href="https://www.bbc.com/news/science-environment-43477233">triple</a> over the next decade. It is clear the problem of plastic pollution has no political or geographic boundaries. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/there-are-some-single-use-plastics-we-truly-need-the-rest-we-can-live-without-99077">There are some single-use plastics we truly need. The rest we can live without</a>
</strong>
</em>
</p>
<hr>
<p>While plastics enter the sea from populated areas, global currents transport them across oceans. Plastics can kill animals, <a href="https://www.sciencedirect.com/science/article/pii/S0048969718346072?via%3Dihub%22%22">promote disease</a>, and <a href="https://www.researchgate.net/publication/322703874_Plastic_waste_associated_with_disease_on_coral_reefs">harm the environment, our food sources and people</a>. </p>
<p>The most devastating effects fall on communities in poverty. New research shows the Great Pacific Garbage Patch is <a href="https://www.nature.com/articles/s41598-018-22939-w">rapidly growing</a>, posing a <a href="https://link.springer.com/article/10.1007/s12526-019-00952-0">greater threat to wildlife</a>. It reinforces the global movement to reduce, recycle and remove plastics from the environment. </p>
<p>But to really tackle this problem we need creative solutions at every level of society, from communities to industries to governments and international organisations. </p>
<p>To take one possibility, what if we invested in fast-growing, sustainably cultivated bamboo to replace millions of single-use plastics? It could be produced by the very countries most affected by this crisis: poorer and developing nations. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/designing-new-ways-to-make-use-of-ocean-plastic-120180">Designing new ways to make use of ocean plastic</a>
</strong>
</em>
</p>
<hr>
<p>It is only one of many opportunities to dramatically reduce plastic waste, improve the health of our environments and people, and to help communities most susceptible to plastic pollution.</p><img src="https://counter.theconversation.com/content/122538/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chandra Salgado Kent 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>The Great Pacific Garbage Patch, a floating accumulation of rubbish the size of a continent, has whales and dolphins in its heart.Chandra Salgado Kent, Associate Professor, School of Science, Edith Cowan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1195832019-07-08T20:36:28Z2019-07-08T20:36:28Z‘Free Willy’ law spotlights contradictions in how Canadians see animal rights<figure><img src="https://images.theconversation.com/files/282951/original/file-20190707-51273-1u9pn59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Canada's Parliamentary debate around captive whales and dolphins touched on the animals' intellectual and social properties. </span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Watching captive whales or dolphins for entertainment will eventually become a thing of the past in Canada. Lawmakers recently adopted the Ending the Captivity of Whales and Dolphins Act — dubbed <a href="https://www.cnn.com/2019/06/10/americas/canada-whale-dolphin-bill-intl-hnk/index.html">the “Free Willy” bill</a>, named after the 1993 hit movie.</p>
<p><a href="https://www.parl.ca/LegisInfo/BillDetails.aspx?billId=8063284&Language=E">Bill S-203</a> prohibits keeping, breeding and importing marine mammals from the <a href="http://www.marinemammalcenter.org/education/marine-mammal-information/cetaceans/">cetacean family (including whales, dolphins and porpoises</a>) for entertainment or for any other reason besides rescue and rehabilitation. Now-retired senator Wilfred Moore sponsored the bill after <a href="https://www.theglobeandmail.com/politics/article-house-passes-bill-to-end-whale-dolphin-captivity/">viewing the 2015 documentary</a> <a href="http://www.blackfishmovie.com"><em>Blackfish</em> about the orca Tilikum</a> and the sea park industry. </p>
<p>The only captive whales or dolphins in Canada are now at Marineland in Ontario near Niagara Falls and the Vancouver Aquarium. The latter announced <a href="https://www.cbc.ca/news/canada/british-columbia/vancouver-aquarium-will-no-longer-keep-whales-dolphins-in-captivity-1.4492316">plans to end its captive cetacean program in early 2018</a> and only <a href="https://nationalpost.com/news/politics/free-willy-bill-to-end-whale-captivity-in-canada-set-to-become-law">one dolphin is now there</a>. There are <a href="https://globalnews.ca/news/5376846/canada-whale-dolphin-captivity-ban-marineland/">about 60 cetaceans housed at Marineland</a>, including Kiska, the lone “killer whale,” or orca, captive in Canada. Kiska and the <a href="https://www.cbc.ca/news/canada/hamilton/whales-1.5169138">estimated 55 beluga whales and five bottlenose dolphins</a> at Marineland won’t be freed by the bill, because the ban exempts those already in captivity. </p>
<p>Protecting marine mammals is important and Canada has made itself a leader through the passage of Bill S-203. A <a href="https://d31j74p4lpxrfp.cloudfront.net/sites/default/files/the_case_against_marine_mammals_in_captivity_1.pdf">number of countries</a>, such as Costa Rica, India and Switzerland, prohibit displaying cetaceans for entertainment. In the U.S., some states or counties have banned display and the country strictly regulates the import of wild-caught cetaceans.</p>
<p>With Bill S-203, Canada becomes the first North American country to ban both displaying for entertainment and importing or exporting. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/283123/original/file-20190708-51268-6l8u55.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/283123/original/file-20190708-51268-6l8u55.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283123/original/file-20190708-51268-6l8u55.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283123/original/file-20190708-51268-6l8u55.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283123/original/file-20190708-51268-6l8u55.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283123/original/file-20190708-51268-6l8u55.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283123/original/file-20190708-51268-6l8u55.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">Bottlenose dolphin.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Not progressive enough</h2>
<p>As a professor of animal law, I was delighted to see this bill become law, but I am also aware that Canadian law relating to non-human animals is not progressive enough. </p>
<p><a href="https://www.canlii.org/en/bc/bcsc/doc/1957/1957canlii466/1957canlii466.html?autocompleteStr=pacific%20mea&autocompletePos=1">Since the 1950s</a>, the animal cruelty provision in Canada’s criminal code has been interpreted to exempt most common farming practices from its application.</p>
<p>Instead, where animals’ lives on farms are concerned, farms are subject to <a href="https://www.nfacc.ca/codes-of-practice">codes of practice</a> created primarily by industry stakeholders. These codes are referred to in some, but not all, provincial animal protection laws. They set out minimum standards based on common farming practices and they contain weak enforcement mechanisms. Legal pressure brought to bear on farms is mostly driven by complaints. </p>
<p>With respect to the welfare of farmed animals, <a href="http://diplomatonline.com/mag/2013/09/the-eu-vs-canada-fixing-factory-farms-by-granting-the-5-freedoms/">Canada lags far behind comparable jurisdictions like Australia, New Zealand and the European Union</a>. Compare this situation with the stiff maximum penalty of up to $200,000 for now bringing whales or dolphins into captivity and the <a href="https://www.humanecanada.ca/realities_of_farming_in_canada">contradiction becomes stark</a>. </p>
<p>What Bill S-203 does not address are the interests of the hundreds of millions of other sentient animals — <a href="https://www.animaljustice.ca/blog/over-819-million-land-animals-slaughtered-by-canadian-meat-industry-in-2018">approximately 800 million per year in Canada, and growing</a> — captive on industrial farms for the purpose of producing food.</p>
<h2>Shifting legal landscape</h2>
<p>To be sure, there are differences between animals held captive for our entertainment and those raised for food. Humans need to eat; we don’t need to visit a marine park or aquarium to survive.</p>
<p>But as the field of animal law continues to grow, so does public awareness of the problems with the inconsistent ways that Canadian law protects some animals, while leaving others behind.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Fr26scqsIwk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Animal rights lawyer Lesli Bisgould discusses re-evaluating human’s relationships with animals.</span></figcaption>
</figure>
<p>And the legislature is beginning to take notice. In addition to Bill S-203, <a href="https://globalnews.ca/news/5411341/canada-shark-fin-ban-sharkwater/">Parliament recently banned</a> the import and export of shark fins and <a href="https://www.cbc.ca/news/politics/animal-protection-bill-c84-bestiality-1.5181494">strengthened the Criminal Code</a> related to the offences of animal fighting and bestiality. But there remains work to be done.</p>
<p>Canada’s Bill S-203 debate touched on the intellectual and social properties of dolphins and whales. During the debate on the bill, Sen. Moore argued: </p>
<blockquote>
<p>“Whales, dolphins and porpoises, which together are known as cetaceans, are highly intelligent, emotional and social mammals that roam vast distances in the oceans. In the wild, many species of whales and dolphins live in large family groups, or pods, that can grow to over 100 members. Distinct populations communicate using complex vocalizations that resemble languages.” </p>
</blockquote>
<p>Elizabeth May, leader of the Green Party, and a sponsor of the bill, argued that “the science increasingly makes us understand that what might seem to be simple entertainment and a simple pleasure is actually animal cruelty, because these animals cannot be held in a swimming pool without…real pain and a loss of social contact and normal activities.”</p>
<p>Defenders of the bill reminded Parliament that their offices had heard overwhelming support for the bill from their constituencies. They argued Canadians are no longer willing to abide keeping these animals captive in unnatural environments or forcing them to perform tricks for food.</p>
<h2>Sentient, intelligent, social</h2>
<p>In following the evolution of Bill S-203, I found myself wondering what the world might look like if similar arguments were used to ground reform to the practices related to animals in agriculture — animals that are similarly sentient, intelligent and social.</p>
<p>Hens, for example, can anticipate the future and demonstrate self-control, according to <a href="https://www.sciencedirect.com/science/article/pii/S0003347205000412">research at the University of London</a>. On Canadian farms, however, egg-producing hens continue to be housed in <a href="https://www.cbc.ca/news/business/cage-free-eggs-1.3435333">cramped battery cages</a>, where they cannot spread their wings or engage in natural behaviours. </p>
<p>Research suggests that <a href="https://www.springer.com/gp/book/9781402089084">pigs are fast learners with good memories and complex social structures</a>. And yet, it is common knowledge that pregnant sows on industrial farms are confined in barren metal crates, where they are unable to turn around, for weeks or even months at a time.</p>
<p>Canada should be applauded for freeing Willy from captivity. But the true celebrations should be reserved for when Canadians, as a progressive and compassionate society, decide it’s time to free Babe.</p><img src="https://counter.theconversation.com/content/119583/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jodi Lazare 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>As the field of animal law continues growing, so does public awareness of the problems with inconsistent ways that Canadian law protects some animals, while leaving others behind.Jodi Lazare, Assistant Professor, Dalhousie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1189972019-06-30T19:26:35Z2019-06-30T19:26:35ZDolphin researchers say NZ’s proposed protection plan is flawed and misleading<figure><img src="https://images.theconversation.com/files/281419/original/file-20190626-76743-19wir4o.jpg?ixlib=rb-1.1.0&rect=26%2C28%2C1433%2C825&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hector's dolphins (Cephalorhynchus hectori) are found only in New Zealand. </span> <span class="attribution"><span class="source">Flickr/Scott Thompson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>The New Zealand government recently proposed a plan to <a href="https://www.beehive.govt.nz/release/plan-expand-protection-m%C4%81ui-and-hector%E2%80%99s-dolphins-0">manage what it considers to be threats</a> to Hector’s dolphins, an endemic species found only in coastal waters. This includes the North Island subspecies Māui dolphin.</p>
<p>Māui dolphins are <a href="https://www.iucn.org/resources/conservation-tools/iucn-red-list-threatened-species">critically endangered</a> and Hector’s dolphins are endangered. With only an estimated 57 Māui dolphins left, they are literally teetering on the edge of extinction. The population of Hector’s dolphins has declined from 30,000-50,000 to 10,000-15,000 over the past four decades. </p>
<p>The Ministry for Primary Industries (<a href="https://www.mpi.govt.nz/">MPI</a>) and the Department of Conservation (<a href="https://www.doc.govt.nz/">DOC</a>) released a <a href="https://www.doc.govt.nz/dolphintmp">discussion document</a> which includes a complex range of options aimed at improving protection. </p>
<p>But the proposals reveal two important issues – flawed science and management.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/despite-its-green-image-nz-has-worlds-highest-proportion-of-species-at-risk-116063">Despite its green image, NZ has world's highest proportion of species at risk</a>
</strong>
</em>
</p>
<hr>
<h2>Flawed science</h2>
<p>Several problems combine to overestimate the importance of disease and underestimate the importance of bycatch in fishing nets. For many years, MPI and the <a href="https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10835716">fishing industry</a> have argued that diseases like toxoplasmosis and brucellosis are the main <a href="https://openseas.org.nz/wp-content/uploads/2017/06/MPI_AEBAR_2016.pdf">cause of decline in dolphin populations</a>. This is not shared by New Zealand and international experts, who have been highly sceptical of the evidence. Either way, it is not an argument to ignore dolphin deaths in fishing nets.</p>
<p>Three international experts from the US, UK and Canada <a href="https://www.doc.govt.nz/globalassets/documents/conservation/native-animals/marine-mammals/maui-tmp/hectors-risk-assessment-workshop-panel-recommendations-appendix-1.pdf">examined MPI’s work</a>. They concluded that it is not possible to estimate the number of dolphin deaths from disease, much less claim that this impact is more serious than bycatch. On the other hand, it is easy to obtain an accurate estimate of the number of dolphins dying in fishing nets, as long as enough observers are allocated. MPI has failed to do so. Coverage has been so low that MPI’s estimate of catch rates in trawl fisheries is based on one observed capture. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/280876/original/file-20190624-97794-v04rv9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/280876/original/file-20190624-97794-v04rv9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280876/original/file-20190624-97794-v04rv9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280876/original/file-20190624-97794-v04rv9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280876/original/file-20190624-97794-v04rv9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280876/original/file-20190624-97794-v04rv9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280876/original/file-20190624-97794-v04rv9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It would be possible to estimate dolphin deaths in trawl nets if enough observers were allocated.</span>
<span class="attribution"><span class="source">Supplied</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The MPI model used in the public discussion document (and described in more detail in <a href="https://www.mpi.govt.nz/protection-and-response/sustainable-fisheries/managing-our-impact-on-marine-life/protecting-hectors-and-maui-dolphins/">supporting materials</a>) is complex, and a one-off. It is based on a “habitat model” of dolphin distribution, but fits actual dolphin sightings poorly. </p>
<p>Another problematic aspect of the method is that there is no clear time frame for the “recovery” of dolphin populations to the specified 90% of the unimpacted population size for Hector’s dolphins and 95% for Maui dolphins. This is one of the first things any decision maker would want to know. Would Māui dolphins be held at the current critically endangered population level for another 50 years? If so, this dramatically increases their chance of extinction.</p>
<h2>Flawed management options</h2>
<p>The second set of problems concerns the management options themselves. These are a complex mix of regulations that differ from one area to another, for gillnets and trawling. They frankly don’t make sense. The International Whaling Commission (<a href="https://iwc.int/home">IWC</a>) and International Union for Conservation of Nature (<a href="https://www.iucn.org/de">IUCN</a>) have recommended banning gillnet and trawl fisheries throughout Māui and Hector’s habitats. MPI’s best option for Māui dolphins comes close to this in the middle of the dolphins’ range, but doesn’t go as far offshore in the southern part of their range.</p>
<p>The South Island options for Hector’s dolphin are much worse. MPI’s approach has been to try to reduce the total number of dolphins killed to just below the level they believe is sustainable. MPI has <a href="https://www.fisheries.govt.nz/dmsdocument/35007-aebr-2019214-spatial-risk-assessment-of-threats-to-hectorsmaui-dolphins-cephalorhynchus-hectori">invented its own method</a> for calculating a sustainable number of dolphin deaths, which is much higher than the <a href="https://www.federalregister.gov/documents/2016/03/02/2016-04537/guidelines-for-assessing-marine-mammal-stocks">well-tested method used in the United States</a>. The next step has been to find areas where the greatest number of deaths can be avoided at the least cost to the fishing industry. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/281417/original/file-20190626-76701-42ayyx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281417/original/file-20190626-76701-42ayyx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=629&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281417/original/file-20190626-76701-42ayyx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=629&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281417/original/file-20190626-76701-42ayyx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=629&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281417/original/file-20190626-76701-42ayyx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=790&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281417/original/file-20190626-76701-42ayyx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=790&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281417/original/file-20190626-76701-42ayyx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=790&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Several Hector’s dolphin populations in the South Island are small, but they act as a bridge between larger populations.</span>
<span class="attribution"><span class="source">Supplied</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This sounds reasonable, but fixing the problem only in the places where the largest number of dolphins is being killed will have several negative consequences. Experience shows that fishing effort shifts beyond protected areas, merely moving the problem. </p>
<p>For example, MPI’s proposals leave a large gap on the south and east side of Banks Peninsula, in prime dolphin habitat. If the nearby areas are protected, this gap will be fished, and dolphin bycatch will continue unabated. What’s needed is protection of the areas where dolphins live. </p>
<p>MPI’s focus on reducing the total number of dolphin deaths also ignores the fact that it really matters where those deaths occur. Several Hector’s dolphin populations in the South Island are as small, or smaller, than the Māui dolphin population. </p>
<p>Entanglement deaths have much worse consequences in such small populations, which form a bridge between larger populations. Yet they get no attention in the current options. MPI’s proposals would lead to the depletion of small populations, with increased fragmentation and extinction of local populations.</p>
<h2>Only one option</h2>
<p>If we want to ensure the long-term survival of these dolphins, there is only one realistic solution: to <a href="https://portals.iucn.org/library/node/44109">remove fishing methods that kill dolphins</a> from dolphin habitat. The simple solution is to use only dolphin-safe fishing methods in all waters <a href="https://portals.iucn.org/library/node/44109">less than 100 metres deep</a>. This means no gillnets or trawling in harbours and other coastal waters up to the 100 metre depth contour.</p>
<p>There is no need to ban recreational or commercial fishing, but we must make the transition to selective, sustainable fishing methods. These include fish traps, longlines and other hook and line methods. Selective, sustainable fishing methods also use less fuel than trawling and avoid impacts of trawling and gillnets on the broader marine environment. </p>
<p>We also need more observers and more cameras on fishing boats. MPI’s estimate of how many dolphins are dying in fishing nets is almost certainly an under-estimate. It depends heavily on <a href="https://www.doc.govt.nz/globalassets/documents/conservation/native-animals/marine-mammals/maui-tmp/hectors-risk-assessment-workshop-panel-recommendations-appendix-1.pdf">assumptions that are not supported by data</a>. </p>
<p>With observers on only about 2-3% of the inshore fishing boats, the chances of <a href="https://www.fisheries.noaa.gov/webdam/download/64669267">missing bycatch altogether is very high</a>. Low observer coverage also means boats can fish differently on the days when they have an observer aboard (for example, avoiding areas where they have caught dolphins). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/281413/original/file-20190626-76722-s3yurd.jpg?ixlib=rb-1.1.0&rect=9%2C13%2C613%2C459&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281413/original/file-20190626-76722-s3yurd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281413/original/file-20190626-76722-s3yurd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281413/original/file-20190626-76722-s3yurd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281413/original/file-20190626-76722-s3yurd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281413/original/file-20190626-76722-s3yurd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281413/original/file-20190626-76722-s3yurd.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">Selective fishing methods would protect dolphins and the broader marine environment.</span>
<span class="attribution"><span class="source">Supplied</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>We know what works</h2>
<p>Despite getting a poor report card from the <a href="https://www.doc.govt.nz/globalassets/documents/conservation/native-animals/marine-mammals/maui-tmp/hectors-risk-assessment-workshop-panel-recommendations-appendix-1.pdf">international expert panel</a>, MPI presented a virtually unmodified analysis to the IWC’s scientific committee last month. The committee identified most of the same issues and concluded it needed more time to decide whether MPI’s approach is fit for purpose. Meanwhile the IWC reiterated its recommendation, which it has been making for eight years, to ban gillnets and trawl fisheries throughout Māui dolphin habitat. </p>
<p>In the meantime, dolphins continue to be killed in fishing. We need to make decisions on the basis of scientific evidence available now. All of the <a href="https://www.google.co.nz/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwiGj7ussP7iAhVIbn0KHQs_CxoQFjAAegQIAhAB&url=https%3A%2F%2Fwww.tandfonline.com%2Fdoi%2Fpdf%2F10.1080%2F00288330.2006.9517425&usg=AOvVaw3LDo6pJl3OBu_Ms6ZL7wVG">population surveys</a>, including those funded by MPI, show Hector’s and Māui dolphins live in waters less than 100 metres deep.</p>
<p>The best evidence of what works comes from Banks Peninsula, where the dolphins have had partial protection since 1988, and <a href="https://www.google.co.nz/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwickYTusP7iAhUFVysKHSm0Bs0QFjAAegQIBhAB&url=https%3A%2F%2Fbesjournals.onlinelibrary.wiley.com%2Fdoi%2Ffull%2F10.1111%2Fj.1365-2664.2012.02121.x&usg=AOvVaw1HOp3xsVNyW9A9Po3v8kLu">detailed follow-up research</a>. This population was declining at 6% per year before gillnets were banned to four nautical miles offshore and trawling to two nautical miles. Even though there was no management of disease, the rate of population decline has dropped dramatically to less than 1% per year. If disease were a serious problem, the <a href="https://www.doc.govt.nz/nature/habitats/marine/other-marine-protection/banks-peninsula/">restrictions on gillnets</a> would have made little difference. </p>
<p>A general principle in conservation is that the longer you wait, the more difficult and more expensive it will be to save a species, and the more likely we are to fail.</p><img src="https://counter.theconversation.com/content/118997/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elisabeth Slooten is a Professor in the Department of Zoology at the University of Otago and a Trustee of the New Zealand Whale and Dolphin Trust. She has been carrying out research on Hector's and Maui dolphins since 1984, with Professor Stephen Dawson, Dr William Rayment and a team of graduate students at the University of Otago.</span></em></p><p class="fine-print"><em><span>Professor Stephen Dawson is Head of the Department of Marine Science at Otago University and a Trustee of the New Zealand Whale and Dolphin Trust. He has studied Hector's dolphin extensively since 1984.</span></em></p>The endangered Hector’s dolphins are found only in coastal seas in New Zealand, but conservation experts describe New Zealand’s proposed protection plan for the marine mammals as misleading.Elisabeth Slooten, Professor, University of OtagoSteve Dawson, Professor, University of OtagoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1149162019-04-08T08:35:06Z2019-04-08T08:35:06ZAll female mammals have a clitoris – we’re starting to work out what that means for their sex lives<figure><img src="https://images.theconversation.com/files/267997/original/file-20190408-2905-1gg86bs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">New research shows dolphins have a large clitoris that is similar to the human organ. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-bottlenose-dolphin-573059539?src=VcHtRICT_kHgByAR0Sebaw-1-5">from www.shutterstock.com</a></span></figcaption></figure><p>Female enjoyment of sex is typically associated with the human species. </p>
<p>But actually all female mammals have a clitoris, the highly sensitive organ that is linked with pleasure and orgasm in women. </p>
<p>And research is now starting to slowly unpack how the clitoris might be involved in sexual encounters in mammals. For example, a <a href="https://plan.core-apps.com/eb2019/abstract/fc3c5a76-2dab-4997-af46-25f331877a19">research paper</a> presented at a biology conference this week showed that the clitoris in dolphins is very large, and more complex than we previously thought. </p>
<p>Let’s take a look at the biology and evolution of the clitoris – for science. </p>
<h2>It starts in the uterus</h2>
<p>All babies, regardless of whether they are destined to become a boy or a girl, begin development in the womb with a small bulge called a <a href="https://www.sciencedirect.com/science/article/pii/S0301468118300938?via%3Dihub">genital tubercle</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-makes-you-a-man-or-a-woman-geneticist-jenny-graves-explains-102983">What makes you a man or a woman? Geneticist Jenny Graves explains</a>
</strong>
</em>
</p>
<hr>
<p>If the developing fetus is destined to become male, the fetal testes will produce the male hormone testosterone and the genital tubercle will develop into a penis. If, on the other hand, the fetus is destined to become a female, the fetal ovary will not produce any hormones and instead the genital tubercle will develop into the clitoris.</p>
<p>Both structures look very similar in the early days of pregnancy.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=607&fit=crop&dpr=1 600w, https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=607&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=607&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=763&fit=crop&dpr=1 754w, https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=763&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/267990/original/file-20190408-2909-1fnqf61.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=763&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Human genitals photographed at 11 weeks gestation.</span>
<span class="attribution"><a class="source" href="https://www.instagram.com/p/BlFwtygB6dT/">strictly_nub_theory on Instagram (screen shot April 8 2019)</a></span>
</figcaption>
</figure>
<p>Since the penis and the clitoris both develop from the same structure, they share many similarities. </p>
<p>The clitoris has a hood in humans: this is the same as the foreskin in males. The clitoris has a glans, which is the same structure as the head of the penis in men. Both the penis and clitoris become engorged with blood when stimulated. And both structures are full of nerves which, at least in humans, provide a pleasurable sensation when stimulated.</p>
<h2>A very recent science</h2>
<p>But compared to the penis, the clitoris is not well studied even in humans. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/you-need-more-than-just-testes-to-make-a-penis-111625">You need more than just testes to make a penis</a>
</strong>
</em>
</p>
<hr>
<p>Amazingly, it was not until the late 1990s that the complete anatomy of the human clitoris was accurately described by Australia’s <a href="https://www.surgeons.org/profile/helen-oconnell">first female urologist, Helen O’Connell</a>. Her work to understand the detailed <a href="https://www.smh.com.au/lifestyle/health-and-wellness/get-cliterate-how-a-melbourne-doctor-is-redefining-female-sexuality-20181203-p50jvv.html">form and function of the clitoris</a> provides answers to some basic biological questions about sex. </p>
<p>Such research also has implications in pelvic area surgery, where doctors can use this knowledge to avoid any loss of sexual function. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=462&fit=crop&dpr=1 600w, https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=462&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=462&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=580&fit=crop&dpr=1 754w, https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=580&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/267973/original/file-20190408-2931-u4fphu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=580&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 external aspect of the human clitoris is just a very small portion of its entire structure. In this image, the dark pink and white structures are internal.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/structure-clitoris-medical-poster-female-anatomy-1197679213?src=87NTGfmDtNY46wvpns4cGQ-1-0">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-it-normal-for-girls-to-masturbate-112393">'Is it normal for girls to masturbate?'</a>
</strong>
</em>
</p>
<hr>
<h2>Female hyenas are special</h2>
<p>Because the penis and clitoris develop from the same tissue in the fetus, anything that affects the hormone balance in the embryo can impact its development. A great example of this is seen in the female spotted hyena. </p>
<p>In this mammal, the female rules the pack. She is larger and more muscular than the males because she is exposed to high levels of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4069199/">male hormones during embryonic development</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/268004/original/file-20190408-2912-15uss0l.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">Just grin and bear it, or is this enjoyable?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rare-sight-spotted-hyenas-mating-627054032?src=MeaKEfW2NcN-LFfoZOazug-1-13">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>But this more muscled physique comes at a cost. The male hormones also affect the clitoris, turning it into a structure that looks like the male penis. </p>
<p>Unfortunately for the female hyena this 20cm clitoris contains the birth canal. So, the female needs to both mate and give birth through her clitoris, which often splits in the process, causing a <a href="https://africageographic.com/blog/good-bad-gory-birth-hyena-cub/">high death rate in first time mothers</a>.</p>
<p>There are other known differences in clitoris anatomy across species too. </p>
<p>The urethra is the tube through which urine passes to the outside of the body. Many animals have the urethra running through the clitoris (as it does in the penis) while in humans, the urethra opens at the base of the clitoris.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/260599/original/file-20190225-26171-veh10r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/260599/original/file-20190225-26171-veh10r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/260599/original/file-20190225-26171-veh10r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/260599/original/file-20190225-26171-veh10r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/260599/original/file-20190225-26171-veh10r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/260599/original/file-20190225-26171-veh10r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/260599/original/file-20190225-26171-veh10r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Most mammals also have a <a href="https://www.nationalgeographic.com/science/phenomena/2013/09/03/a-long-lost-bone/">small bone in the clitoris</a> to help it become rigid during intercourse. This is known as the <em>os clitoris</em> and again shares a counterpart in the penis, the <em>os penis</em>. <em>Os clitoris</em> and <em>os penis</em> bones are present in most mammals, and humans are unusual in not having one in either organ. </p>
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Read more:
<a href="https://theconversation.com/lascivious-virgins-and-lustful-itches-womens-masturbation-in-early-england-101260">Lascivious virgins and lustful itches: women's masturbation in early England</a>
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<h2>Getting lost in the moment</h2>
<p>The jury is still out on whether all mammals experience orgasm. </p>
<p>Non-human primates <a href="https://www.popsci.com/science/article/2013-09/fyi-do-animals-have-orgasms">almost certainly do</a>, but it is difficult to measure pleasure in animals. </p>
<p>What is certain is that females who stick around for longer during the act of mating are much more likely to become pregnant and produce more offspring. So if a clitoris does enhance enjoyment, then it would be strongly selected for in nature through increasing the females chance of having offspring. </p>
<p>Although the clitoris is not well studied, there is evidence of larger clitorides – yes, this is the plural of clitoris – in animals in which sex plays an important part in relationship building. Examples include the matriarchal hyena, bonobo chimps, humans and most recently in the dolphin.</p>
<h2>Lots of surprises</h2>
<p>A <a href="https://plan.core-apps.com/eb2019/abstract/fc3c5a76-2dab-4997-af46-25f331877a19">paper released this week</a> reveals that female bottlenose dolphins have clitorides similar to humans, and that female dolphins may experience sexual pleasure. </p>
<p>Researchers used a combination of dissections and 3D scans to explore the female genitalia of dolphins in detail. </p>
<p>The shape and structure of the dolphin clitoris is very similar to that of the human. Both animals have extensive areas of erectile tissue that are larger than the clitoral hood. The skin under the clitoral hood also contains bundles of nerves that may increase sensitivity, raising the possibility that sexual experiences can be pleasurable for female dolphins.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=599&fit=crop&dpr=1 600w, https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=599&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=599&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=752&fit=crop&dpr=1 754w, https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=752&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/267992/original/file-20190408-2918-1wfmi9a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=752&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Computer reconstruction of the clitoris of the bottlenose dolphin, which researchers say is remarkably similar to the human clitoris in its structure and shape.</span>
<span class="attribution"><a class="source" href="https://www.eurekalert.org/pub_releases/2019-04/eb-nio032819.php">Dara Orbach, Mount Holyoke College</a></span>
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<p>However, there are also some differences in the location of the clitoris with respect to the vaginal opening and how it would be stimulated during copulation. </p>
<p>These comparative studies help us learn about the function of genitalia, and the evolution of sexual bonding across species.</p>
<p>Science has revealed a bizarre array of penis shapes found in mammals, from a <a href="https://imgur.com/gallery/kpzam">four-headed penis in the echidna</a> to <a href="https://lafeber.com/vet/wp-content/uploads/male-bifid-penis-copy.jpg">two-headed penises</a> in many marsupials. </p>
<p>It remains to be seen what surprises the clitoris has in store for us.</p><img src="https://counter.theconversation.com/content/114916/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Pask receives funding from the NIH, ARC and NHMRC. </span></em></p><p class="fine-print"><em><span>Deidre Mattiske 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>It was not until the late 1990s that the anatomy of the human clitoris was accurately described by Australia’s first female urologist. And now research in animals is starting to catch up.Andrew Pask, Professor, The University of MelbourneDeidre Mattiske, Research Fellow, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.