July Fishlines Newsletter
Vol. 35, No. 7
Pursuing Cause of Death in Gulf of Alaska Whales
On Memorial Day weekend in May NOAA enforcement officers asked marine mammal specialists at the Alaska Sea Grant Marine Advisory Program to respond to a dead fin whale sighted near Kodiak. Over the next six weeks more large whale mortalities were reported by mariners and pilots.
Kate Wynne and Bree Witteveen began gathering NOAA Stranding Network data—they documented and photographed the carcasses and looked for more by surveying the east coast of the Kodiak archipelago by air—and contacted scientists and others in the region. Since the first sighting, a total of 10 fin whale and 8 humpback mortalities have been documented and, curiously, all appear to have died the latter part of May.
Both whale species feed in groups on small fish and invertebrates, filtering them with their baleen. Scientists asked themselves—were the feeding groups of whales killed together? Did they consume a toxin or were they violently impacted?
Wynne, Witteveen, and other biologists have pursued many possible human-influenced and natural causes, but as of mid-July the cause of death remains unknown. The single whale that was necropsied proved to be healthy with a nice fat layer at the time of death, ruling out an illness or lack of good nutrition. Most dead whales were too decomposed for sampling by the time they were found, confounding the mystery.
Biotoxins caused by warm water–induced harmful algal blooms are a possibility, although tissue from the sampled fin whale tested for domoic acid came back negative. Results are not in yet on possible paralytic shellfish poisoning toxin. Temperature sampling showed that the waters were significantly warmer than average at the time of the whale mortality.
Scientists have followed up on other possible causes such as sonar, seismic exploration, and even radionuclides from the Fukushima reactor. While whales are vulnerable to sonar testing, it is ruled out in this case because US Navy sonar exercises took place in the area June 15–26, well after the mortalities. No reports of dead whales have been made since the Navy exercises began and researchers continue to monitor the situation.
To follow up on the seismic angle, Wynne contacted the Bureau of Ocean and Energy Management (BOEM). The only seismic testing in the region this spring and summer has been in upper Cook Inlet, in an area seldom visited by baleen whales. To pursue the radionuclide possibility Wynne submitted a muscle tissue sample from a dead fin whale for Cesium 137 analysis, with results pending.
“Part of the mystery is why just whales? Why not their prey? Why are there not sea lions or other consumers in the system showing up in mass die-off mode?” said Wynne. Concerned citizens have offered other possible causes including earthquakes, lightning strike, and human-caused toxin releases.
Wynne and Witteveen complimented the professional network of bird, fish, and mammal biologists in the Gulf of Alaska and the Bristol Bay–Bering Sea area, who have reported unusual events since the mortalities. "The good news is that this has gotten a lot of us to talk to each other, and be alert," Wynne said.
Network scientists represent the Alaska Department of Fish and Game, Alaska Department of Environmental Conservation, US Fish and Wildlife Service, BOEM, National Marine Fisheries Service Alaska Region, NMFS Office of Law Enforcement, National Marine Mammal Laboratory, Shoonaq Tribe of Kodiak, and Agdaagux Tribe of King Cove. Kodiak Marine Advisory agent Julie Matweyou has coordinated testing for harmful algal bloom toxins.
Fin whales and humpbacks are both considered endangered under the Endangered Species Act. Although both species are recovering from decades of commercial whaling, their coastal distribution exposes them to the threats of vessel collision, gear entanglement, and man-made noise, according to the Guide to Marine Mammals of Alaska authored by Wynne.
RaLondes Receive FFA Award
Marine Advisory Program aquaculture specialist Ray RaLonde and his wife, Isabell, received the Alaska FFA Blue and Gold Award for extraordinary service, for developing the Marine Technology Program for the FFA State Convention in May. More than 80 high school students participated in the marine career development events.
“Ray and Issy have been instrumental in helping our FFA Marine Technology event get off the ground and interest young Alaskans in marine industries. Their generous donation of time and talent have been invaluable,” said Kevin Fochs, Alaska state FFA director. “Thanks to the RaLondes for their generosity and dedication to the marine industry.” Ray RaLonde also secured financial support through an educational grant, which allowed FFA to provide unique study kits for students and teachers to incorporate into their programs.
Notes from the Field
Notes from the Field is a new series of stories by Alaska Sea Grant Marine Advisory agents and researchers describing their work activities. A recent story by Melissa Good described May outdoor education events in Unalaska for Seas and Rivers Week—scientists in the classroom, Dockside Discovery Day, safety lessons, and a beach cleanup. The inaugural Notes from the Field, by Kate Wynne, highlighted annual observations of killer whales in the Kodiak area, some of which have been watched for 30 years.
Fishlines is a monthly newsletter that highlights Alaska Sea Grant activities. Alaska Sea Grant supports wise use and conservation of Alaska's marine resources through research, education, and extension. Photo in banner by K. Byers. If you do not wish to receive future Fishlines via email, contact Sue Keller.