Dozens of West Coast gray whale deaths prompt federal investigation
Prompted by the fatal stranding of ?70 gray whales on the U.S. West Coast this year, federal scientists have launched a major scientific investigation aimed at identifying the cause or causes of the die-off among the migrating mammals that number about 27,000 and are a popular North Coast attraction in places like Bodega Bay.
A young gray whale that washed up last week on Limantour Beach at Point Reyes National Seashore was the 15th recorded stranding in the greater Bay Area.
An additional 78 strandings have occurred in Mexico and Canada, bringing the five-month total to 148 deaths of Eastern North Pacific gray whales.
NOAA Fisheries, the federal agency charged with protection and conservation of marine mammals, said the trend warranted declaration of an “unusual mortality event,” unleashing funding and resources for an investigation that could take months or years to find answers.
Deborah Fauquier, a NOAA veterinary medical officer, said Friday the declaration was justified by an unexpected and significant die-off that “demands an immediate response.”
An investigative team of experts from the United States, Canada, Mexico and possibly worldwide will be formed to “determine what might be causing the die-off, such as environmental conditions, disease or human activities” and “make informed decisions to protect this important marine species,” she said in a teleconference with reporters.
Commercial whaling once brought gray whales close to extinction, but the population has rebounded and is no longer listed as an endangered or threatened species.
David Weller, a NOAA wildlife biologist based in La Jolla, said the most recent population estimate was 27,000, the “highest level of abundance” since 1967.
Many of the whales that have perished this year were in bad shape or malnourished, possibly due to “poor feeding or feeding conditions” last summer and fall, Weller said. Some are thought to have died after being struck by ships, including vessels using the shipping lanes into San Francisco Bay.
Gray whales, which grow up to ?49 feet long and weigh about 90,000 pounds, spend summers feeding in Alaska’s Bering and Chukchi seas, embarking in the fall on their 10,000-mile round trip to calving lagoons off the coast of Baja Mexico, eating little until they return to Arctic waters.
On their northward journey along the West Coast the whales are “under peak nutritional stress” and would be “on the thin side but not necessarily emaciated,” Weller said. The current population “may exceed the ability of the environment to provide enough food for them,” he said.
Sue Moore, a biological oceanographer at the University of Washington, noted the Arctic is “changing very, very quickly and whales are going to have to adjust to that.” Studies have documented an Arctic sea ice retreat attributed to climate change.
John Calambokidis, a biologist at Cascadia Research Collective in Washington, conceded that ?70 whale deaths is a fragment of the population, but said most dead whales will sink and as few as 10% will wash ashore. Many whales stranded in remote parts of Alaska will go unreported, he said.
The spring migration is still in its early stages in Washington, Canada and Alaska, he noted.
Fauquier said the loss of 70 whales in the four West Coast states is concerning because the 18-year average loss from January to May is 14.8 whales.
In Mexico, about half of the whales observed in the lagoons this winter were reported as “skinny,” compared with the annual average of 10% to 12% whales normally seen in that condition, a NOAA report said.
Weller said the gray whale population is capable of rebounding from a loss of at least 6,000 animals.
A previous mortality event in 1999 to 2000 tallied more than 650 emaciated whales stranded along the West Coast of North America, including 222 in the U.S.
“We’ve got our finger on the pulse,” he said. “We know it can recover.”
You can reach Staff Writer Guy Kovner at 707-521-5457 or email@example.com. On Twitter ?@guykovner.
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