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<div dir="ltr" style="text-align: left;" trbidi="on"><br /><br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><br /><tr><td style="text-align: center;"><img alt="Southern Right Whale (Eubalaena australis) breaching, Valdes Peninsula, Argentina, Atlantic Ocean (2 of 7)" height="435" src="http://images.nationalgeographic.com/wpf/media-content/photos/000/739/cache/right-whale-calves_73982_990x742.jpg" style="margin-left: auto; margin-right: auto;" width="650" /></td></tr><br /><tr><td class="tr-caption" style="text-align: center;">A southern right whale breaching off of <a class="zem_slink" href="http://whc.unesco.org/en/list/937" rel="unesco" target="_blank" title="Península Valdés">Peninsula Valdes</a>, <a class="zem_slink" href="http://maps.google.com/maps?ll=-34.6,-58.3833333333&spn=10.0,10.0&q=-34.6,-58.3833333333%20(Argentina)&t=h" rel="geolocation" target="_blank" title="Argentina">Argentina</a>.</td></tr><br /></tbody></table><br /><h2 class="subtitle"><br />The "mass mortality" of hundreds of southern right whale calves mystify scientists. </h2><br /><div class="c1"><br /><span class="c0 c4"><b>Surprisingly large numbers of  southern right whale calves are dying off the coast of Argentina,  sparking concerns among marine scientists and conservation officials.</b></span></div><br /><div class="c1"><br /><b><span class="c0 c4">Overall, southern</span><span class="c0 c4"><a class="c2" href="http://animals.nationalgeographic.com/animals/mammals/right-whale/"> </a></span><span class="c5 c4"><a class="c2" href="http://animals.nationalgeographic.com/animals/mammals/right-whale/">right whales</a></span><span class="c0 c4"> are doing much better than their</span><span class="c0 c4"><a class="c2" href="http://www.iucnredlist.org/details/41711/0"> </a></span><span class="c5 c4"><a class="c2" href="http://www.iucnredlist.org/details/41711/0">endangered</a></span><span class="c0"><a class="c2" href="http://www.iucnredlist.org/details/41712/0"> </a></span><span class="c5 c4"><a class="c2" href="http://www.iucnredlist.org/details/41712/0">brethren to the north</a></span><span class="c0 c4">. But for one group of southern right whales that gives birth off</span><span class="c0 c4"><a class="c2" href="http://maps.nationalgeographic.com/map-machine#s=r&c=-42.500006711326655,%20-63.933334350585945&z=8"> </a></span><span class="c5 c4"><a class="c2" href="http://maps.nationalgeographic.com/map-machine#s=r&c=-42.500006711326655,%20-63.933334350585945&z=8">Peninsula Valdés, Argentina (map)</a></span><span class="c0 c4">, fate has not been so kind.</span></b></div><br /><div class="c1"><br /><span class="c0">Hundreds of the Peninsula Valdés whales  have died since monitoring of their population size began in 1971,  researchers report in a</span><span class="c0"><a class="c2" href="http://www.int-res.com/articles/meps_oa/m493p275.pdf"> </a></span><span class="c5"><a class="c2" href="http://www.int-res.com/articles/meps_oa/m493p275.pdf">study</a></span><span class="c0"> published this month in the journal </span><span class="c0 c3"><i><a class="zem_slink" href="http://www.int-res.com/journals/meps/" rel="homepage" target="_blank" title="Marine Ecology Progress Series">Marine Ecology Progress Series</a></i></span><span class="c0">. From 1971 to 2011, 630 of the right whales died—adults and young ones combined.</span></div><br /><div class="c1"><br /><span class="c0">But 77 percent of those deaths occurred  between 2003 and 2011. And of those recent deaths, 89 percent have  occurred in the calves. Scientists are still struggling to understand  why.</span></div><br /><div class="fullwidthphoto"><br /><img alt="" src="http://images.nationalgeographic.com/wpf/media-content/photos/000/739/73952-cb1385572286.jpg" /></div><br /><div class="c1"><br /><span class="c0">Changes in monitoring efforts over the  years could probably account for some of the increase in recorded  deaths, researchers acknowledge in the study. But they can't account for  all of it.</span></div><br /><div class="c1"><br /><span class="c0">Something else is going on that has so far defied the efforts of scientists to get to the bottom of the situation.</span></div><br /><div class="c1"><br /><span class="c0">It's a real frustration, said</span><span class="c0"><a class="c2" href="http://faculty.utah.edu/u0232369-VICTORIA_J_ROWNTREE/research/index.hml"> </a></span><span class="c5"><a class="c2" href="http://faculty.utah.edu/u0232369-VICTORIA_J_ROWNTREE/research/index.hml">Vicky Rowntree</a></span><span class="c0">, a behavioral ecologist at the <a class="zem_slink" href="http://business-schools.findthebest.com/l/155/university-of-utah-eccles-ut" rel="fdbbusiness" target="_blank" title="David Eccles School of Business">University of Utah</a> in Salt Lake City and director of the right whale program at</span><span class="c0"><a class="c2" href="http://www.whale.org/"> </a></span><span class="c5"><a class="c2" href="http://www.whale.org/">Ocean Alliance/Instituto de Conservación de Ballenas</a></span><span class="c0"> in <a class="zem_slink" href="http://maps.google.com/maps?ll=-34.6033333333,-58.3816666667&spn=0.1,0.1&q=-34.6033333333,-58.3816666667%20(Buenos%20Aires)&t=h" rel="geolocation" target="_blank" title="Buenos Aires">Buenos Aires, Argentina</a>.</span></div><br /><div class="c1"><br /><span class="c0 c4"><b>No Common Cause</b></span></div><br /><div class="c1"><br /><span class="c0">A meeting of marine biologists and  veterinarians convened by the <a class="zem_slink" href="http://en.wikipedia.org/wiki/International_Whaling_Commission" rel="wikipedia" target="_blank" title="International Whaling Commission">International Whaling Commission</a> in 2010  to study the problem settled on three possible explanations: low food  abundance, disease, or toxins such as</span><span class="c0"><a class="c2" href="http://www.nwfsc.noaa.gov/hab/habs_toxins/marine_biotoxins/da/"> </a></span><span class="c5"><a class="c2" href="http://www.nwfsc.noaa.gov/hab/habs_toxins/marine_biotoxins/da/">domoic acid</a></span><span class="c0"> or saxitoxin produced by</span><span class="c0"><a class="c2" href="http://www.nwfsc.noaa.gov/hab/habs_toxins/index.html"> </a></span><span class="c5"><a class="c2" href="http://www.nwfsc.noaa.gov/hab/habs_toxins/index.html">harmful algal blooms</a></span><span class="c0">.</span></div><br /><div class="c1"><br /><span class="c0">"A lot of our research has been trying to  look at those [explanations]," said lead study author Rowntree. But so  far, researchers and veterinarians have been unable to find a common  cause of death in the hundreds of samples taken from the dead calves.</span></div><br /><div class="c1"><br /><span class="c0">A small number of calves show evidence of  disease while others contain low levels of toxins. Figuring out whether  the calves got enough food is harder to determine, Rowntree explained.  (See</span><span class="c0"><a class="c2" href="http://news.nationalgeographic.com/news/2012/04/130412-diseases-health-animals-science-environment-oceans/"> </a></span><span class="c5"><a class="c2" href="http://news.nationalgeographic.com/news/2012/04/130412-diseases-health-animals-science-environment-oceans/">"New Diseases, Toxins Harming Marine Life."</a></span><span class="c0">)</span></div><br /><div class="c1"><br /><span class="c0">Blubber thickness is one way researchers  look at whether these calves are getting enough food or not. They also  look to other markers of nutritional stress in body tissues or the  whales' baleen—located in a whale's mouth which they use to strain food  out of seawater.</span></div><br /><div class="c1"><br /><span class="c0">The timing of the deaths has both  confused and helped efforts to understand what's going on. Baby whales  in certain years seem to have died shortly after birth, while in other  years, they've died later in the May-December calving season. This  suggests that more than one cause may be responsible for these "high  mortality" events, the study authors write.</span></div><br /><div class="c1"><br /><span class="c0">"But the timing of the mortality might  give us some clue as to why they died," said Rowntree. If a calf died  shortly after birth, that could indicate a wide-scale food shortage  problem.</span></div><br /><div class="c1"><br /><span class="c0">If a calf died later in the year, when  the whales start to feed on krill and copepods, then perhaps the young  ones are ingesting a toxin or pollutant, she explained. (See</span><span class="c0"><a class="c2" href="http://news.nationalgeographic.com/news/2008/06/080617-sea-lions.html"> </a></span><span class="c5"><a class="c2" href="http://news.nationalgeographic.com/news/2008/06/080617-sea-lions.html">"Sea Lion Seizures May Result From Toxic Algae."</a></span><span class="c0">)</span></div><br /><div class="c1"><br /><span class="c0">Analyses of <a class="zem_slink" href="http://en.wikipedia.org/wiki/North_Atlantic_right_whale" rel="wikipedia" target="_blank" title="North Atlantic right whale">Northern Atlantic right whale</a>  populations indicate they ingest algal toxins produced during harmful  algal blooms. Krill and copepods are grazers and take in toxins along  with the algae they eat. Those toxins, in turn, are transferred to the  whales when they gulp down their prey.</span></div><br /><div class="c1"><br /><span class="c0">"The adults can deal with it," Rowntree said. "But maybe the toxins are too strong for the babies."</span></div><br /><div class="c1"><br /><span class="c0 c4"><b>Blame It On Birds?</b></span></div><br /><div class="c1"><br /><span class="c0">Another possible explanation—supported by Rowntree and</span><span class="c0"><a class="c2" href="https://events.iwc.int/index.php/scientific/SC65a/paper/viewFile/285/257/SC-65a-BRG15"> </a></span><span class="c5"><a class="c2" href="https://events.iwc.int/index.php/scientific/SC65a/paper/viewFile/285/257/SC-65a-BRG15">discussed</a></span><span class="c0"> at an April 2013 international meeting of veterinarians in Sausalito, California—is harassment by kelp gulls (</span><span class="c0 c3"><i>Larus domincanus</i></span><span class="c0">).</span></div><br /><div class="c1"><br /><span class="c0">"They're large gulls and they've learned  to feed on the skin they peck from the backs of the whales," she  explained. "They make a hole in the skin and they attack it over and  over during the season."</span></div><br /><div class="c1"><br /><span class="c0">Some enterprising birds started the</span><span class="c0"><a class="c2" href="http://phenomena.nationalgeographic.com/2012/07/06/argentinian-gulls-are-eating-whales-or-at-least-bits-of-whales/"> </a></span><span class="c5"><a class="c2" href="http://phenomena.nationalgeographic.com/2012/07/06/argentinian-gulls-are-eating-whales-or-at-least-bits-of-whales/">strategy</a></span><span class="c0"> in the early 1980s, and it has since spread to other gulls all over the peninsula.</span></div><br /><div class="c1"><br /><span class="c0">Although it seems that the mothers have  learned how to avoid such pointed attention from the birds, the calves  haven't. "So most calves have a chain of lesions along their backs from  being pecked by the gulls," Rowntree explained.</span></div><br /><div class="c1"><br /><span class="c0">It's quite possible that this harassment  could contribute to calf deaths around Peninsula Valdés, the animal  ecologist said. That's the only big problem these right whales seem to  have in common that sets them apart from other southern right whale  populations which aren't experiencing such large numbers of deaths.</span></div><br /><div class="c1"><br /><span class="c0 c4"><b>Watching What They Eat</b></span></div><br /><div class="c1"><br /><span class="c0">For now, Rowntree and her colleagues are  looking at tracking where these whales feed. There is some evidence  suggesting that low prey abundance, specifically Antarctic krill (</span><span class="c0 c3"><i>Euphasia superba</i></span><span class="c0">), could lead to increases in whale deaths.</span></div><br /><div class="c1"><br /><span class="c0">Female southern right whales depend on  krill to bulk up their blubber reserves before they give birth. During  their calves' first few months of life, the mothers don't eat.</span></div><br /><div class="c1"><br /><span class="c0">If the mothers aren't storing enough blubber, they may not be able to provide adequate nutrition for their babies.</span></div><br /><div class="c1"><br /><span class="c0">Whale diets leave specific signatures in  their baleen, depending on where in the world the animal fed, Rowntree  explained. "If the mothers eat in the Southern Hemisphere, that food  [has] a unique signature."</span></div><br /><div class="c1"><br /><span class="c0">If they can link increases in Peninsula  Valdés right whale deaths with low krill abundance, then perhaps they  can narrow in on what's causing so many calves to die.</span></div><br /><div class="c1"><br /><span class="c0 c4"><b>Wait and See</b></span></div><br /><div class="c1"><br /><span class="c0">It's still a little too early to tell how  all these deaths will affect the population's overall numbers. But it  doesn't look good.</span></div><br /><div class="c1"><br /><span class="c0">Last year, researchers recorded 116  southern right whale strandings in the Peninsula Valdés population. That  accounts for nearly three percent of the western South Atlantic stock,  the study authors write.</span></div><br /><div class="c1"><br /><span class="c0">"No other known single-year die-off of baleen whales is as large," the researchers note.</span></div><br /><div class="c1"><br /><span class="c0">Female southern right whales are sexually  mature when they turn nine, Rowntree said. Since the die-off began in  2005, females born that year will be able to start having babies in  2014.</span></div><br /><div class="c1"><br /><span class="c0">Southern right whale pregnancies last a  year. Then it takes a year for the mother to nurse her calf and then  another year for her to build up her blubber reserves for the next  pregnancy.</span></div><br /><span class="c0">So it will be another three years before  researchers have a clear picture of how badly the Peninsula Valdés  population has been affected.</span><br /><br /><a href="http://news.nationalgeographic.com/news/2013/12/131201-southern-right-whale-calf-deaths-animal-oceans-science/?utm_source=Facebook&utm_medium=Social&utm_content=link_fb20131205news-whalcalf&utm_campaign=Content">Mysterious Deaths Threaten a Population of Southern Right Whales</a><br /><br /><br /><br /><div class="zemanta-pixie" style="height: 15px; margin-top: 10px;"><br /><a class="zemanta-pixie-a" href="http://www.zemanta.com/?px" title="Enhanced by Zemanta"><img alt="Enhanced by Zemanta" class="zemanta-pixie-img" src="http://img.zemanta.com/zemified_e.png?x-id=3e37c754-d16e-4d39-9608-fe14e12db960" style="border: none; float: right;" /></a></div><br /></div><br />