Examination of gray whale deaths could answer bigger questions about the environment
More than 30 gray whales have washed ashore in Washington state this year. But that’s only a fraction of the number of stranded whales seen along the West Coast between Mexico and Alaska. This "unusual mortality event" (UME) has triggered an investigation by researchers, though answers won't come quickly.
John Calambokidis, a biologist who co-founded Olympia-based Cascadia Research Institute, has been trying to understand the whale strandings in Washington state. He talked with Morning Edition host Kirsten Kendrick via Skype about what’s happening and how we may only be seeing a fraction of the problem.
SCRATCHING THE SURFACE
Calambokidis said up to 90 percent of the gray whales that die likely go undocumented. Researchers believe they're sinking at sea.
He said whales that are thin and don't have a lot of blubber on them tend to sink. The whale carcasses that have washed ashore have appeared emaciated.
WHAT DO THEY DO WITH THEM?
For the carcasses examined, Calambokidis said, researchers first must document the mortalities — to make sure the animals aren't counted more than once. They also verify the species and age class. Then comes the external investigation.
"Sampling blubber, looking for evidence of ship strikes or entanglement, and, if the animal is fresh enough, conducting a full necropsy,” he said. That’s when a team cuts into the animal to examine stomach contents, organs and document its condition to determine the cause of death.
As for the broad investigation into the widespread strandings, Calambokidis says the process is in preliminary stages.
“We’re…focused on collection of tissues so that they are available for testing later,” he said. “Many of those tests have not yet been conducted.” More information will be gathered later, Calambokidis added.
PARALLELS TO THE PAST
Calambokidis says there are parallels between this year’s deaths and a previous UME in 1999-2000. Back then, about 50 gray whales died in two years — a record number.
"We saw some similar condition in the animals. The timing of the strandings were similar. And many of the animals were extremely malnourished, which is another thing that appears to be common in some of the preliminary examinations that we've done so far," he said.
Calambokidis said determining malnourishment can be tricky. "Gray whales have this thick blubber layer and that actually remains intact even when they are malnourished,” he said, “but it can have much less oil or fat in it.
"Also, because this is the tail end of when they're normally fasting, we typically expect them to not be in great body condition anyway.”
Researchers struggle with how much blame to place on the environment.
Calambokidis says shrinking ice cover in the Arctic may have actually benefitted gray whales, since less ice means easier access to feeding areas.
"But that may be much less critical to how well the environment can support them than, say, the density of prey and how well is the prey aggregated in ways that they can really take advantage of," he said.
HOW LONG WILL IT LAST?
Calambokidis expects to see a lull in gray whale deaths in Washington through the rest of the summer and into the fall. That's because only a small portion of the population is currently in our waters.
He said researchers probably won't be able to determine the status of this mortality event until next spring.
WHY IS THIS IMPORTANT?
Calambokidis said it's important to pay attention to what's going on with gray whales because they're a product of their environment.
"They face threats from things like entanglement, ship strikes, changes in ecosystem and food supply,” he said. “We can gain insight into how those things might be affecting other species or our environment as a whole."