Gray whales continue to wash up dead and emaciated, but causes remain elusive
On the ocean off Alaska’s south-central coastline, a team of researchers is trying to figure out what killed at least 17 male Pacific gray whales over the course of a week. To do so, they’re taking tissue samples from whales to determine what they eat.
To date, scientists have not been able to determine the cause of the deaths.
“Gray whales are such an important species, from an ecological perspective,” says biologist Mike Stengel, who is helping the team study the whales. “From an evolutionary perspective, it’s an amazingly fascinating species to study.”
A gray whale called Fanny is seen off Alaska’s west coast. The species, which is listed as endangered, has undergone a population boom in recent decades.
Credit:
Mikko Taskinen
As the animals make their way north, they migrate about 120 miles to the Chukchi Sea, according to the International Whaling Commission, which oversees whaling worldwide.
The Chukchi Sea is a big population hub for the whales. But it’s also not a great place for them to be. It’s a cold, nutrient-rich waterway bordered by the Sea of Okhotsk, where the Chukchi Inlet meets the Gulf of Alaska.
At this point in the years-long migration, a gray whale has already made it the distance north to the Chukchi Sea. But that whale can’t sustain itself in the region, because of two factors: cold water and low levels of food in the water.
The Chukchi Sea also has a high density of small fish called sablefish. Sablefish are a kind of herring, and it’s been suggested that gray whales feed on them, at least in winter.
The whales typically swim south and arrive in the Chukchi Sea roughly three months after they swim north. In April, they have the best chance of finding food in the region, because many fish are in spawning or migrating in the area.
But the whales