NOAA Declares “Unusual Mortality Event” for Whale Deaths

Bears feeding on a fin whale carcass in Larson Bay. Via NOAA

Kayla Desroches/KMXT

The carcasses of thirty whales that have stranded along the Gulf of Alaska and the Alaska Peninsula have puzzled scientists since the first discoveries this May, and now NOAA is giving the cases “unusual mortality event” status. That means that the stranding event is unexpected, involves a large number of marine animal deaths, and requires immediate attention.

While scientists have considered biotoxins as well as environmental causes like patches of unusually warm water, the reason for the deaths remains unknown. At a media teleconference today to discuss the new UME status, NOAA Fisheries lead marine mammal scientist, Teri Rowles, says they’ve tested one whale out of the thirty reported.

“Most of the carcasses have been not retrievable. They’ve been floating and/or they’ve been stranded for a temporary period of time in inaccessible areas and a lot of those have been moderately to severely decomposed,” she said.

They have run some tests for biotoxins, but so far they’ve been inconclusive. Rowles says the sample they collected and tested was negative for domoic acid.
 
“We still have the saxitoxin results pending,” said Rowles. “But it hasn’t been a sample that’s been successful for us in the past, so even though the one sample we tested was negative, it was not the most appropriate sample to collect and test for biotoxins.”

Rowles says they can’t say for certain that the whale was not exposed to a biotoxin. In order to rule-in or rule-out possible causes of the whale deaths, she says they need more samples, but big whales are difficult to access in order to conduct necropsies.

“Trying to investigate large whale mortality events provides a lot of logistical complications and getting access to good samples, getting access safely to carcasses, and even finding a place for carcasses to be towed and examined,” said Rowles.

Many of the whales have washed up in the Kodiak Archipelago, and marine mammal specialist and on-site UME Coordinator, Bree Witteveen, says there are a few reasons why that could be. One is the high number of fin, humpback, and grey whales that already pass through those waters during summer.

“As far as the number of eyes that we have around Kodiak is quite a big greater than you would have around the Alaska Peninsula and further west and so we may simply just be able to see more of the carcasses and not document additional carcasses,” said Witteveen. “And further, if it was a very localized event, then you would expect the carcasses to be more localized when they are finally sighted.”

At the teleconference, NOAA representatives and partners said UME status should help answer some of these questions. NOAA Fisheries Stranding Network Coordinator for the Alaska Region, Aleria Jensen, said it will give them access to additional resources.

“We’ll be bringing together scientists, members of the stranding network, other national and international colleagues, so it becomes a much greater effort,” said Jensen. “We’ll also be able to be collaborating with the expertise that exist in the UME working group, so that will be an important resource for us as well as we move forward.”

But that doesn’t mean results will be quick.

Rowles says the next step is to put together the investigative team and pull the data together. She says it’ll be a slow process and it could be a while before they find an answer if they reach one.