Gray whales continue to wash up dead and emaciated, but causes remain elusive in a year in which an unusual record high in Arctic sea ice has some scientists wondering if Mother Nature is working overtime to help them survive.
Experts say that even though global warming is a significant factor in killing large whales, “the numbers are so few that it’s very difficult to say that warming is the cause” in many cases, said Bob Peterson, director of the National Oceanic and Atmospheric Administration’s marine mammal stranding program.
In the last four years, there have been at least five large-animal strandings in the Arctic during the annual summer melt season, but most of those animals washed up dead and had no signs of injury.
Among the dead whales was an orca that was nearly 1,500 years old, scientists say. Experts have determined that it was likely an adult orca, though it was still too weak to hunt.
“It’s hard to see how the animal could have survived for so long, or died from natural causes,” said Mark Eakin, senior scientist at the Marine Mammal Stranding Center in Ventura, Calif. “The whale was clearly dying from some type of stress related to the ice melt.”
A single whale strand like this one is unusual in the four years of whale strandings in the Arctic. (Photo: NOAA)
At this point, the NOAA scientists who have been studying the strandings agree with the National Park Service scientists who studied the orca that saw the whale lying on the sea floor for several days: “Ice has nothing to do with this case,” said Tom Sexton, a fisheries biologist for NOAA’s marine mammal stranding program.
However, he said, “the lack of disease in the carcass, coupled with the age and overall condition of the animal, leads me to believe it died from an illness.”
The death has been classified as a “multisurvivor,” in which one animal has survived and multiple animals have died.
The NOAA experts do not know what was causing the illness, but experts suggest that the animal’s illness may have begun as soon as it was found on the sea floor.
The carcass has made it to shore