DIE-OFF, MARINE WILDLIFE - USA (03): (ALASKA) SEAL, WALRUS
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From: Per Leines Lausund <veterinary.surgeon@gmail.com> [edited]
We had problems with increased mortality in grey seals in the North Sea countries in the late 1980s due to mass migration of Greenland seal to new areas (reduced number of human and furred predators had something to do with that; the increasing numbers of Greenland seals obviously found the fish-rich coast of Norway enticing!) bringing with them a morbilli (distemper) virus they were adapted to, whereas the grey seals were not. Might be worth checking.
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Lt Col Per Leines Lausund DVM MPH
<veterinary.surgeon@gmail.com>
Staff Veterinary Officer
Defence Command Norway
<veterinary.surgeon@gmail.com>
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[2]
Date: Fri 14 Oct 2011
Source: Alaska Dispatch [edited]
<http://www.alaskadispatch.com/article/walruses-suffer-similar-disease-afflicting-alaska-ringed-seals>
Arctic ringed seals aren't the only marine mammals suffering an unusual skin-lesion outbreak along Alaska's northern coasts.
Walruses that have hauled out by the thousands at Point Lay in Northwest Alaska during recent summers -- an event driven by climate change -- are also turning up with bizarre, festering sores.
Scientists estimate perhaps 600 are infected. Instead of wounds on their faces and rear flippers, red abscesses pepper the animals'
entire bodies. But apparently only a few have perished.
Still, scientists from a number of agencies are working to answer several questions, including whether the outbreaks in the 2 species are related. They also worry the lesions could eventually lead to deaths among Pacific walrus, an animal more than 100 000 strong that's being considered for protections under the Endangered Species Act.
"Is it the bubonic plague or just a really bad case of acne?" asked Tony Fischbach, a federal walrus biologist who first noticed the sores on some walruses late this summer [2011].
As in the case of the ringed seals, biologists are working with the North Slope Borough Department of Wildlife Management, pathology experts, and others. They've sent skin and tissue samples to labs in the US and Canada, but haven't pinpointed a cause. Everything from viruses to toxins is being considered.
It doesn't appear that a huge numbers of walruses have the lesions. At various times, an estimated 20 000 walruses have gathered on the beach.
Leo Ferreira III, the former mayor in Point Lay, a village of 200 residents west of Barrow, said the sores seem to have contributed to the deaths of some walruses.
"Most of them that are dying got the lesions on them," said Ferreira, an Inupiat walrus hunter. He provided a little help last month [September 2011] as scientists collected flesh samples from the animals for testing. He's seen 2 dead ones with lesions.
"This is the 1st time this is happening," he said. "But this is also happening with the ringed seals. We're very concerned. It's because we think there is a disease spreading through them."
Sprawling walrus herds began hauling out on the beach near the village in 2007, for the 1st time in memory, as temperatures warmed. Walrus experts say it's because climate change has melted the sea ice the animals normally use as a diving platform for bottom foraging.
Fischbach said biologists this summer witnessed new behavior among the walruses at Point Lay. Previously, they did their diving for clams and mud-dwelling worms near the beach. But that's not a rich feeding ground.
So many walruses used the Point Lay beaches as their base camp. They made long trips to feed at a site about 100 miles [160 km] off the coast of Wainwright, a village north east of Point Lay. With the ice gone, the walruses had no place to rest, Fischbach said. Some would swim for 2 weeks before they returned to the beach, where they'd rest a few days before leaving on another long trip.
Fischbach first spotted a sick walrus in late August [2011]. He was there for an unrelated radio-tagging effort. On the edge of a huge herd of animals, he crawled across the beach, trying to stay low and out of sight.
One day he came across an abandoned calf that barely moved and appeared to be dying. He first thought sea gulls had picked at it, but he later saw other walruses with similar sores. "This little guy had lesions all over him," Fischbach said. "That caused me concern because it was near death."
Almost every walrus that swam onto the beach, especially single female adults, approached the calf. Some tried nudging it toward the herd, without results. "They seemed to be very interested in it, but they moved on after a while," Fischbach said.
Fischbach saw other walruses with the lesions, but they appeared to be healthy despite the open wounds across their body. The sores weren't from jousting with tusks, something walruses are famous for when gathered in herds.
"These lesions are very different from scars and tusk strikes," said Fischbach. "Those heal up right away. This was different because across the entire body you had large pock marks, like a really bad case of acne."
He didn't know how many had been affected, because he was on the edge of the herd. But he reported the sightings to the US Fish and Wildlife Service.
Scientists who flew to the scene to assess the problem have estimated that 6 per cent of the 10 000 to 20 000 animals that have hauled out near Point Lay have the lesions, said Jason Herreman, a biologist with the North Slope Borough. That would mean at least 600 had the lesions.
Several groups are now working to determine the cause of the wounds, said Teri Rowles, coordinator of the Marine Mammal Health and Stranding Response Program under the National Oceanic and Atmospheric Administration.
They're also working on the ringed seal problem. In recent weeks, North Slope Borough biologists have found close to 50 dead ringed seals that had lesions and patchy hair loss. Julie Speegle of NOAA [National Oceanic and Atmospheric Administration] said [that] lesions have been found in the animals' respiratory system, liver, heart, and brain as well.
The NOAA office in Alaska is also working with the borough's department to prepare data to request a finding of an "unusual mortality event" for the ringed seals, Rowles said.
Such a finding, allowed under the Marine Mammal Protection Act, could free up federal funds and additional experts to determine what's hurting the seals. Once a request is submitted, an international panel of experts will determine if the ringed seals qualify for the finding.
The outbreak among ringed seals is reportedly occurring in Chukotka, Russia, and in northern Canada, and officials said they are working with biologists to determine if there's a link with seals in those countries. Harp seals in Greenland had similar problems earlier this year [2011].
"We don't know what's going on, but we're looking at infectious agents," Rowles said. "Is it bacterial, viral, fungal? And we're looking at biotoxins and other chemical contaminants, as well as overall metabolism."
Is it possible the animals more prone to illness because they're now forced to swim long distances that leave them fatigued with weak immune systems?
"That's one of the concerns," said Rosa Meehan, chief of the Marine Mammals Management division in the US Fish and Wildlife Service. "As their environment changes they may become more susceptible to things like disease."
Back in Point Lay, many of the walruses have left their beach haul-out and moved on for the winter, some likely to beach haul-outs in Russia, she said. Ferreira said that a few have stuck around near the village.
If they're still there by the time the lagoon outside the village freezes, he said he'll head across the ice and kill one for food. But he'll avoid the sick animals. "I'd rather not," he said. "This is the 1st time I've seen this kind of thing."
[byline: Alex DeMarban]
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[Many thanks to Dr Per Lausund for his comments. We are awaiting more information on this die-off. - Mod.MPP
Mass seal mortality associated with phocine distemper virus (PDV) infection has been documented several times along the European and North American coasts. The virus was first documented in 1988, when harbor seals (_Phoca vitulina_) and gray seals (_Halichoerus grypus_) died in large numbers off the coast of northern Europe (the episode referred to above by Dr Per Lausund). A more recent episode in Europe occurred in 2002, with an estimated 30 000 harbor and gray seal deaths.
Millions of seals of various species inhabit the waters surrounding North America; populations of most species are believed to be stable or increasing, and no epidemics on the scale of those reported in Europe have been reported. PDV disease in the United States was first reported in harbor seals on the east coast during the winter of 1991-92, and serologic testing of gray and harbor seals suggested that a PDV-like strain or strains were circulating enzootically in the region. The clinical signs associated with PDV infection are tremors, spasms, respiratory distress, and abortion. Not quite the skin lesions reported in this episode.
Portions of this comment were extracted from <http://wwwnc.cdc.gov/eid/article/17/2/pdfs/10-0190.pdf>.
The skin lesions in walruses seem to be quite different from those in ringed seals. Pictures of the walrus lesions can be seen at <http://www.alaskadispatch.com/sites/default/files/images/topic/arctic/usgs-walrus-5.jpg>
and of the seal lesions at
<http://www.alaskadispatch.com/sites/default/files/imagecache/slideshow_image/images/topic/arctic/seal-face-386.jpg>.
The proximal cause of the disease might be a different one, but there could be a common origin. A multi-factorial etiology is very likely.
The histopathology results will certainly shed some light.
The interactive HealthMap/ProMED-mail map for the state of Alaska is available at <http://healthmap.org/r/1lfz> - Mod.PMB]
[see also:
Die-off, marine wildlife - USA (02): (AK) seal, RFI 20111014.3074 Die-off, marine wildlife - USA: (NH) RFI 20111012.3052 Q fever - USA (02): (AK) seals 20110911.2771
2003
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Phocine distemper virus, seals - UK 20030112.0099
2002
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Phocine distemper virus, seals - N. Europe (02) 20020821.5101] .................................................tg/ejp/mpp/pmb/mj/sh/ll
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