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Whale Blow Out

Ferry passengers have become whale-watchers over the past few months, jolted from their morning doldrums by the sight of gray whales swimming alongside their boats. This year's number of sightings, between Pier 7 in San Francisco and San Pablo Bay, has reached a record at 85. Although some of the sightings may be of the same whales, even if that number were reduced by half, says the Oceanic Society's James Gilardi, it is still much higher than the normal number of sightings, about five per year. The high numbers have scientists scratching their heads over possible causes.

While European explorers in the late 1700s/early 1800s often reported seeing whales spouting in the Bay, by the early 1900s, overhunting had caused gray whale numbers to plummet. In the 1970s, gray whales and most large whales were added to the Endangered Species list. Since they have been protected from hunting (with the exception of yearly quotas set for indigenous peoples in Alaska and Siberia), grays along the Pacific coast have recovered to an estimated 26,000 whales. In 1994, they were delisted.

The recent increase in sightings could have positive or negative implications for their recovery, says Gilardi - or both. In addition to the live whales, 19 whales have been found stranded (washed ashore, sometimes dead) along Bay shores this year, part of a statewide total of 57 strandings, up from an average of 15 per year. On the positive side, the frequent sightings may mean that gray whales are recovering to their pre-whaling levels and may be exploring new foraging opportunities: the Bay's soft mucky bottom is perfect habitat for grays, which feed by sucking up large quantities of mud and using their baleen to sieve out bottom-dwelling worms and shrimp-like creatures.

But the apparent increase in whales in the Bay (dead and alive) might also be a sign that something is wrong with their foraging grounds off the coast (grays migrate along the California coast as part of their 6,000-mile journey between Mexico and Alaska) or in the Bay itself. "We could be seeing both recovery and a problem occurring at the same time," says Gilardi.

Some scientists think grays may have reached the ecosystem's carrying capacity: in other words, too many whales, not enough food. But studies have shown that the whales are only using a small portion of their best feeding grounds, says Gilardi, which doesn't support the carrying capacity theory. Other causes suggested for the strandings are stress from high intensity underwater sounds produced by Naval sonar tests or poisoning from toxic algal blooms or environmental contaminants. Gilardi is skeptical about the sonar and algae theories - in part because their impacts would likely be more localized whereas the strandings have occurred all along the coast - but he is more reluctant to rule out possible effects of exposure to contaminants, in the Bay or elsewhere. "They could be eating something, accumulating a biotoxin, or it may even be a disease problem; we just don't know," says Gilardi. "It would be a shame for them to be returning to the Bay only to be contaminated by our historic abuse of the Bay."

Joe Cordaro of the National Marine Fisheries Service also theorizes that the increase in whales in the Bay may not be related to poor feeding conditions in the ocean since the majority of the stranded whales in the Bay are full-bodied - not emaciated - adults. The Service is examining the theory that boat collisions may have caused some of the Bay strandings, but so far they've only been able to attribute one or two deaths to boats. Like Gilardi, Codaro remains puzzled by the increase in whale sightings and strandings in the Bay. "Right now, it's all speculation," he says of the various explanations. "We really need to look at what 's happening over a five-year period." In April, the Oceanic Society began a five-year study that will use photo identification, boat surveys, behavioral observations, bottom sampling, and prey analysis to try to piece together the mystery of the gray whales in the Bay.

Spotters of live whales in the Bay are asked to call (415)409-GRAY and to report stranded or dead whales to the Marine Mammal Center at (415)289-SEAL.

Contacts: Joe Cordaro (562)980-4017 or James Gilardi (415)441-1159

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