Dead Fin Whale (Balaenoptera physalus)

Observation: A large approximately 59 feet (18 meters) fin whale was reported by St. Paul Citizen Sentinels Mike and Esther Baldwin. A Level A Stranding Form was completed and filed with the NMFS marine mammal stranding network and researchers flew to St. Paul immediately to guide the Aleut Community of St. Paul Island- Ecosystem Conservation Office staff in conducting a necropsy and collecting samples to determine a cause of death. Paul Melovidov, BeringWatch

Consult: This sighting is one observation in a string of dead whale sightings that have been designated as the 2015 Gulf of Alaska Large Whale Unusual Mortality Event (UME). From May to mid-August 30 large whales were reported including 11 fin whales, 14 humpback whales, 1 gray whale and 4 other unidentified large cetaceans. Additional reports of dead whales also occurred off the coast of British Columbia, Canada. Scientists in the United States and Canada have yet to determine the cause of the 2015 large whale UME, however, the investigation is ongoing. Unfortunately, many of the whales were floating at sea or in an advanced stage of decomposition.

Scientists were only able to obtain samples from one dead whale in Alaskan waters. Because all of the dead whales were species that feed by filtering water through plates of baleen in their jaws, one possible cause under investigation is that the whales may have ingested biotoxins present in harmful algal blooms such as red tides. Since the mid-1990s, UMEs associated with biotoxins from harmful algal blooms have become more common, the majority of which have been attributed to toxicity from domoic acid or brevetoxin. Toxic algal blooms can be caused by unusually warm ocean conditions, such as those observed in the eastern North Pacific since 2013 in conjunction with a sea surface temperature anomaly that has been nicknamed “the blob.” The unusually warm ocean conditions linked to the blob can have a variety of impacts on the marine ecosystem and have also been implicated in the 2013 California sea lion UME and increased strandings of Guadalupe fur seals. For more information, visit, BeringWatch Lauren Divine, BeringWatch

LEO says: Alaska Department of Fish & Game, Fin Whale – The fin whale population was decimated by commercial whaling in the 1800s and early 1900s. It was listed as endangered under the Endangered Species Conservation Act, the predecessor to the Endangered Species Act (ESA), in 1970. When the ESA was passed in 1973, the fin whale was listed as endangered throughout its range. It is also designated as depleted under the Marine Mammal Protection Act (MMPA).

Resource:

Alaska Department of Fish & Game – For general information on Fin Whale, see the Wildlife Notebook (PDF 54 kB) Series.