Grey Whales Dying - Scientists Seeking Answers
Newsworld, Canada, 7-15-99
Researchers faced with more dead grey whales on the shore of Washington are trying to determine whether the problem is too many whales or too little food. They say many of the whales died with low body fat, indicating they probably starved to death. More than 150 dead grey whales have been found along the Pacific Coast this year, including seven in British Columbia, and 24 in Washington. When the seventh whale was found in B.C. in early June a Vancouver Aquarium veterinarian said the deaths may be caused by more than one factor. And more whales could have come ashore this year because of extra stormy weather last winter. Normally, for every whale found dead, it's estimated there may be 10 or 20 others that never wash up on shore. All of the whales have been found during the species' annual migration north from Mexico
Gray Whale Toll Raising Alarm
By Rene Sanchez, Washington Post, April 30, 2000; Page A03
Gray whales keep turning up dead on the beaches along the West Coast this spring, and scientists who study the giant, mysterious creatures are having a hard time figuring out why. Each year at this time, thousands of gray whales in the Pacific swim north on their annual migration from warm, shallow lagoons off Mexico, where they breed and give birth, to their summertime feeding grounds in the chilly depths of Arctic seas. It is one of the most epic journeys in the animal kingdom, and something might now be going wrong along the way. Then again, the opposite could be true: The rash of deaths might be an encouraging sign of growth for the species, which in the past few decades has made a strong comeback from the brink of extinction. So far, no one knows. About two dozen gray whales, which as adults extend over 30 feet long and weigh as much as 40 tons, have washed up over hundreds of miles of shoreline from Southern California to the San Francisco Bay this month. The tally is higher than it was at this time last year - midway through the migration season. By the end of the last migration season, 47 gray whales had been found dead on the California coast.
The rising number of whale deaths has many scientists worried and puzzled. Last year's total was three times higher than the annual average for the past decade. And the total in 1998 was about double what the average had been. "No one is pushing the panic button yet," said Joseph Cordaro, a biologist for the National Marine Fisheries Service in Long Beach, Calif. "But we have to find some definitive answers, because this is unusual." The detective work is daunting. By the time they are found in the sand, whale carcasses are usually decomposing, which makes necropsies difficult. There also seems to be no clear pattern to the latest deaths. Gray whales are not being found dead in roughly the same spots along the coast, nor do most of them appear to be victims of man-made hazards such as fishing nets or boats. Biologists also say that many of the whales do not look extremely malnourished. Those being found are both young and old, male and female.The lack of consistent clues is even prompting some biologists to wonder whether the deaths may in fact be no cause for alarm. The rising number of beached whales, they say, may only be a natural side effect of their population boom.
Some biologists are speculating that the gray whale population may now be growing at a rate greater than its food sources in the Arctic can sustain. There is also reason to believe that El Nino weather conditions in recent years have warmed waters in ways that have made the things they eat most more scarce. And do they eat. Every summer, gray whales spend months scouring the ocean floor gulping sediment in search of food. Most pack on more than 10,000 pounds before they make the long trip back south to Mexico for the winter. They need the blubber as fuel, because they rarely do much dining during either leg of their marathon route. If El Nino is to blame for food shortages, scientists say that it could take years for their feeding habitats to be fully restored. Because gray whales swim in small groups near the shore - whale watching is a popular tourist attraction along much of the Pacific Coast--scientists can keep close watch on them. Marine groups also take aerial photographs of their annual migration. From those observations, some biologists say that overall the gray whales appear to be thinner than they once were. That discovery suggests competition for food is getting tougher, and that more of their deaths could be from starvation. But it all may be nature's way of restoring balance. "More gray whales just don't seem to have such a good layer of blubber anymore for their migration," Cordaro said. "Some people think they may be reaching their capacity in their environment."
Clusters of gray whales have even spent a few weeks this year in the San Francisco Bay, foraging on its bottom and seeming to make attempts to create a habitat. That phenomenon is amazing biologists. Until now, migrating gray whales had not ever shown signs of taking up even temporary residence so far south along the Pacific Coast, especially in waters so heavily trafficked by people and shipping. "In previous years, that was unheard of," said James Gilardi, a biologist with the Oceanic Society, a nonprofit marine conservation group. "It flies in the face of everything we know about their migration habits." Sightings of whales in the bay have gone from rare to routine so quickly that last week the Oceanic Society launched a five-year study of what they are doing there. Researchers plan to track the whales' behavior regularly and to plumb the bottom of the bay to examine samples of the turf they are foraging. But because most of the gray whales being spotted there appear to be healthy, biologists are also busy taking skin and blubber samples from the carcasses of those that have washed up in Southern California and elsewhere. In case a disease, and not starvation, is at the root of the problem, they have begun searching for evidence of either virus-carrying parasites or man-made toxins. Some biologists say that every budding theory for why more gray whales are being found dead during their migration may turn out to be partly true. "It's a widespread situation and it has been happening for a few years to gray whales," Gilardi said. "We don't think we're dealing with some kind of fluke."