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A Whale of a Trek : 'Tis the Season for Watching the Mammals as They Head for Baja California to Calve and Breed on First Leg of Majestic 12,000 -Mile Annual Migration

January 01, 1988|GORDON GRANT | Times Staff Writer

Through the sunniest of days and--it was learned not long ago--even through the blackest of nights with no obvious change in their ponderous pace, the great California gray whales are making their way down the coast on the first leg of their annual 12,000-mile round-trip migration from the Bering Sea to the warm waters off Baja California.

Whale-watching, whether from a boat or a shore cliff, is the thing to do during the coming weeks. Each one of scores of the monsters will take about 10 hours to pass along the approximately 40-mile Orange County coast, many of them unnoticed in the dark hours.

Whether they keep moving at night during this long migration has been a much-discussed question for years.

"But we are sure now that they just keep moving right along when it gets dark," said Stephen Reilly, marine biologist for the National Marine Fisheries Service in La Jolla. "When night comes, it doesn't seem to make much difference to them. They just keep moving along at about their usual three to four miles per hour."

Scientists discovered this by tagging a number of whales during 1985 and 1986 with tiny radio transmitters so their movements could be tracked.

How do you attach a radio transmitter to a 45-ton whale in the open sea?

You do it with one of the most antiquated of weapons.

"We used crossbows and arrows," said Mike Bursk, a marine biologist who has worked with the National Marine Fisheries Service since 1978 on various projects, including the tagging program, and who also is an on-board lecturer and skipper of a whale-watching boat operating out of Dana Point Harbor.

"We were working out along the Channel Islands, Santa Cruz, San Miguel, Anacapa, Santa Rosa, all off the Santa Barbara coast," he said. "The transmitters were about the size of a round (butane) cigarette lighter. They had a one-foot whip antenna on the top and a little barb to hook in the blubber on the bottom side.

"The crossbows were so weak they didn't give you any trajectory, so you had to be practically right above the whale. None of them ever seemed to even know they'd been hit."

Bursk said his party tagged 10 whales, and another group of scientists near Monterey used a similar method to put transmitters on another dozen.

Even though good for only about two weeks, the transmitters provided enough information on night-time leviathan activities to prove to biologists such as Reilly and Bursk that the huge, gentle mammals didn't let darkness slow them down.

But, as usual, getting the answer to one question simply brought up another.

For years there has been a theory that the whales navigate by visual means, that is, poking their heads out of the water to pick up landmarks.

"But if that was true, it seems they would have to stop or at least slow down at night," Reilly said. "The implication now is, they use some other method to keep their courses."

Besides, according to Bursk, at least half the herd, now estimated at more than 18,000, stays 30 to 50 miles offshore during much of the long journey, and thus would be out of sight of land.

Celestial navigation--use of sun, moon and stars--or just plain instinct born of thousands of years of traveling the same route are other possibilities.

However they do it, the whales, which can reach 45 feet in length and 45 to 50 tons in weight, begin leaving their feeding grounds in the Bering Sea between Alaska and the Soviet Union in late summer. The first ones, usually pregnant females, begin showing up in Orange County waters in December, and Bursk and other fishing boat captains have seen several in recent weeks.

During January and February, females, males and some calves head for the warm lagoons along the Baja California shore, where the females have their calves and the whales breed and rest for the 6,000-mile trek northward, usually starting in March and continuing through early May, when they again may be watched off Orange County.

The herd of California gray whales was reduced to an estimated 600 during the last century and the first half of the 20th Century when they were hunted for their oil. In 1973, the 14-nation International Whaling Commission called for a moratorium on whaling. Though some countries were slow to cooperate, the gray whales, whose largest herd is the one that passes along California, began to increase in population.

"Counts are still being made, but we estimate the herd at something more than 18,000 now, which probably is quite close to what it was when whaling started more than 100 years ago," Reilly said.

Studies are also being made on how seriously the whales are affected by the scores of commercial and private boats that scoot out from harbors all along the coast to follow them as they cruise slowly along, rising to the surface to breathe and blow their misty spouts and slap the water with their broad flukes as they dive again.

Bursk said he has seen whales change their courses and alter their breathing patterns when vessels get too close.

A federal law requires vessels to keep at least 100 yards behind a whale or group of whales, and never try to cut in front of them.

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