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Killer whale necropsy and disease testing protocol (Updated May 15, 2014)
Killer whale strandings are rare events and biologists and veterinarians should use every stranding as an opportunity to learn more about this species. This protocol, first published in 2005 and recently updated in 2014, will provide guidelines for more comprehensive necropsies and standardize disease screening so that we might learn more about diseases of free-ranging killer whales.
Imagine if you woke up one day and parts of your town were coated in a hard-to-see but highly-toxic chemical. How would you know what to areas to avoid, where to find safety, or even which grocery stores had non-contaminated food?
For humans the answer is signs, police tape, announcements on the radio, and breathless disaster reporting on the television.
But for marine mammals the techniques are a little different.
25 years ago today, the Exxon Valdez spilled tens of millions of gallons of oil into Alaska’s Prince William Sound.
Back before the Exxon Valdez oil spill, people thought killer whales would know better than to swim into an oil spill.
Turns out they were wrong. Many individuals in the two pods of orcas that use Prince William Sound, pods AB and AT1, had direct contact with the spilled oil. The pods suffered large population losses in the years following the spill. Twenty-five years later the AB pod has started to recover, but scientists think the AT1 pod, with only 7 members left, will soon go extinct.
So how do you keep killer whales out of oil spills?
This was a question SeaDoc sought to answer back in 2007. We partnered with NOAA to bring together a group of killer whale experts and spill response professionals to discuss how the Salish Sea’s resident and transient killer whales could be protected. Even though 18 years had passed since the Exxon Valdez event, the Northwest Area Contingency Plan did not include a plan for dealing with killer whales.
Over two days, the workshop participants discussed the effects of oil on cetaceans, killer whale mortality from the Exxon Valdez event, permit issues, risk assessments, response coordination, availability of equipment, pre- and post-event monitoring, and techniques for hazing animals to keep them away from oiled areas.
The result is a much higher level of preparedness to save whales’ lives in the event of a catastrophic spill. The response plan for killer whales has been incorporated into the current Northwest Area Contingency Plan. Responders will have techniques and equipment ready to use. Of course, it’s an open question how effective these techniques will be in any particular spill. It will depend a lot where the spill takes place and how close any killer whales are. But the planned out strategy will certainly be more effective that ad-hoc tactics pulled together in the middle of a crisis.
SeaDoc’s work on killer whales and oil spills is a good example of how we bring people together to solve tough issues, especially issues that involve both sides of the international border that splits the Salish Sea.
Interested in learning more? Read the meeting notes from the 2007 workshop.
Also, see NOAA’s page on oil spill response and killer whales, and a 3/24/2014 report from KUOW’s Ashley Ahearn: EarthFix Conversation: 25 Years Later, Scientists Remember The Exxon Valdez.
What killed the 3-year-old killer whale that washed up in Southern Washington a couple of years ago? Joe Gaydos was one of 15 investigators who studied the whale to try to understand what happened to it. Their report was published February 25, 2014.
Joe was quoted in the Associated Press article about the report:
“This whale was killed from a blunt-force trauma, but [despite] every effort possible, we couldn’t tell if it came from another ship or whale,” said Joseph Gaydos, a co-author of the report and wildlife veterinarian with SeaDoc Society, a program of the Wildlife Health Center at the University of California, Davis’ School of Veterinary Medicine. “The evidence doesn’t support that it was a sonar episode or explosion.”
See the full article by Phuong Le at the Seattle Times:
More information about the report:
L112 Stranding Final Report: The Southern Resident Killer Whales Recovery Plan makes responding to standings of killer whales a priority. The Northwest Marine Mammal Stranding Network has nearly completed its investigation of the stranding involving southern resident L112 (Sooke) on Long Beach, Washington, February 11, 2012. Based on findings from the gross examination and the absence of conclusive histopathology or ancillary test results The Network team found that blunt force trauma was the primary consideration for the acute death of the animal. Weather and sea surface data for coastal Oregon and Washington, and drift patterns for the Columbia River plume suggested that L112 had likely been carried for some days in the Columbia River eddies or drifted from the south before being cast on Long Beach. Sonar and small underwater explosive activities were confirmed by the Royal Canadian Navy on February 4, 5, and 6, 2012 in Canadian waters off Vancouver Island and in the Strait of Juan de Fuca but no marine mammals were observed during the activities. The activities occurred too far to the north and downwind of the stranding location to be a consideration in the stranding. You can find the final draft of the report and background documents at:
Photo: Joe Gaydos conducting the necropsy by Sandy Buckley
At the 2014 North American Veterinary Conference, in Orlando, Florida, Joe Gaydos presented on Salmonella in wildlife. About 10% of the Salmonella outbreaks between 2006 and 2013 were caused by wild animals, and most of these were caused by reptiles and amphibians.
Salmonella infection can be prevalent in wild birds, and has been seen in many wild mammal species including white-tailed deer, raccoons, and river otters.
Relatively little is known about Salmonella in free-ranging marine mammals. It has been isolated from harbor porpoise (Phocoena phocoena), a killer whale (Orcinus orca), sea otters (Enhydra lutris nereis), northern elephant seals (mirounga angustirostris), California sea lions (Zalophus californianus), Northern fur seals (Callorhinus ursinus), and harbor seals (Phoca vitulina). Far more isolations have been made than actual documentation of disease. Salmonella Newport-associated septicemia has been documented in a harbor porpoise and a killer whale. Salmonella also has been isolated from marine birds such as Western gulls (Larus occidentalis). While one study found prevalence of Salmonella in 40% of California sea lion pups and 33% of northern fur seal pups on San Miguel Island, the prevalence in most marine wildlife populations is unknown but probably highly variable.
Download a copy of the paper: Salmonella in Wildlife by J. Gaydos
An estimated 1.2 million cases of salmonellosis occur annually in the United States (approximately 42,000 are laboratory-confirmed and reported to the Centers for Disease Control; CDC). Transmission comes primarily from contaminated food, water or contact with infected animals only some of which are wild animals. Of the 50 Salmonella outbreaks reported by the CDC between 2006 and 2013, only 5 (10%) were related to wildlife. These included the 2013 outbreak related to small turtles (Salmonella Sandiego, Pomona and Poona), two 2012 events associated with hedgehogs (Salmonella Typhimurium) and small turtles (Salmonella Sandiego, Pomona and Poona), the 2011 outbreak connected to Africa dwarf frogs (Salmonella Typhimurium) and the 2010 water frog-related outbreak (Salmonella Typhimurium).
Killer whales (Orcinus orca) are widely distributed throughout the world’s oceans, yet little has been documented about their stranding patterns. Knowledge of stranding patterns improves our ability to examine and sample carcasses and provides a foundation for understanding killer whale natural history, diet, reproduction, anthropogenic stressors, emerging diseases, and patterns of unusual mortality. We compiled published and unpublished killer whale stranding data to describe stranding patterns in the North Pacific Ocean. Between 1925 and 2011, 371 stranded killer whales were reported in Japan (20.4%), Russia (3.5%), Alaska (32.0%), British Columbia (27.4%), Washington (4.0%), Oregon (2.7%), California (5.1%), Mexico (3.8%), and Hawaii (0.8%). Strandings occurred at all times of year, but regionally specific seasonal differences were observed. Mortality and annual census data from Northern and Southern Resident populations were extrapolated to estimate that across the North Pacific, an average of 48 killer whales die annually. However, over the last two decades, an average of only 10 killer whale carcasses were recovered annually in this ocean, making each event a rare opportunity for study. Publication of a standardized killer whale necropsy protocol and dedicated funding facilitated the number of complete postmortem necropsies performed on stranded killer whales from 1.6% to 32.2% annually.
Revised (2014) version is here: http://www.seadocsociety.org/publication/updated-2014-killer-whale-necropsy-protocol/