Whales' starvation a warning about the state of the ocean
Canadian Press Service, Oct. 17, 1999
VANCOUVER (CP) -- Starvation seems the most likely cause of death for more than 100 grey whales found dead along the North American West Coast.
After months of testing samples from the whales that washed ashore last summer, experts say they had too little blubber to sustain them on their long migration from Baja Mexico to the Bering Sea.
"These animals had very low fat reserves," said Dr. Peter Ross of the Canadian Department of Fisheries. "Their blubber thickness was very thin and they essentially looked like they had starved to death."
Grey whales swim about 28,967 km from their summer feeding waters in the Bering Sea to Baja Mexico, where they breed, said Ross.
"In the summertime, these grey whales are essentially bulking up such that they will be able to swim down to Mexico," said Ross. "Then they reproduce, then migrate backwards up to the feeding grounds.
"It really just looks like they just ran out of steam, or a number of them did, on their return trip," he added. Ross said the buildup of toxins does not appear to be a factor in the whales' deaths."We found actually fairly low levels of pesticides and PCBs," said Ross, referring to polychlorinated byphenyls, a fat-soluble chemical that has been banned since the 1970s. "It's good news from a contaminant point of view," he said.
A U.S. researcher at the Centre of Whale Research in Washington state concluded recently that a dramatic increase in the death of killer whales around southern Vancouver Island is probably linked to contamination from PCBs.
Ross said the situation with the greys should be monitored.
"Obviously, these grey whales are telling us something very importantabout the state of our oceans," he said. "We've seen other things happening in the Pacific Northwest that concernus as humans, such as declining salmon returns and other problems," he said.
Ross believes the grey whales, which are filter feeders, were victims of a drop in food production in the Bering Sea. He said that although 100 whales washed ashore, the actual body count is closer to 1,000.
"It is a higher number than usual and it probably is a bit of a symptom that the population was a little bit stressed as far as food supply is concerned," said Ross.
Another indication of low food supplies is the lack of calves spotted during the whales' northward migration, he said.
"We observed very, very few calves returning with the females northwards," said Ross. "We suspect this is another indication that during their feeding . . . up in the Bering Sea, the females didn't get enough nutrients in order to support their reproductive cycle."
In the past century, whalers hunted grey whales nearly to extinction. But the population rebounded and is now estimated at about 26,000 off the west coast.
Ross believes the whales may have reached their peak population for their feeding grounds, so as their population increases so does their mortality.
"This might be a natural phenomenon that is related to the numbers of grey whales that our environment can support," he said.