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Science / Medicine : Fishing and Pollution Pose Increasing Threat to Dolphins, Porpoises : Sea life: The danger is not as dramatic as the one faced by whales, scientists say. But it is real nonetheless, and has pushed some species to the brink of extinction.

December 03, 1990|MARK A. STEIN | TIMES STAFF WRITER

MONTEREY, Calif. — Grass-roots and governmental efforts ended the wholesale slaughter of the Earth's great whales and saved some species from ignominious extinction for the sake of lamp oil, fertilizer and pet food.

But scientists at a recent symposium here warned that the whales' compact cousins, porpoises and dolphins, continue to be killed in numbers at least as large as those racked up by the deadliest harpoon-wielding whalers of earlier times.

Extinction, for some species at least, may be only a decade away.

Scientists at the American Cetacean Society conference said some cetaceans--the scientific order of whales, dolphins and porpoises--are vanishing slowly because of people's growing appetite for fish and the rapid pollution of the seas. And while this scenario is less dramatic than death by harpoon, it nonetheless amounts to extermination, they contend.

"In one sense, we have traded the harpoon for the sewage outfall and the fishing net," said Scott Kraus of the New England Aquarium in Boston, while describing the danger now facing cetaceans.

"There is great reason to be concerned," said Robert Brownell of the U.S. Fish and Wildlife Service station in San Simeon, Calif. "For about half the cases where we have enough information to make a judgment (about the possible extinction of a species), things are going to hell in a hand basket."

Bernd Wursig, a professor in the Marine Mammal Research Program at Texas A&M University, said 28 species of small cetaceans are in "very real and immediate danger" of extinction, many by the end of the decade.

Fishing is the most dangerous threat for several reasons, scientists postulated in two dozen papers presented over two days. One reason is that humans out-compete cetaceans for food, leaving too few squid, for example, in a traditional breeding ground to support a new generation of juveniles and their parents.

Another is that fishing boats inadvertently snare and suffocate porpoises and dolphins in the huge nets used to sweep oceans clean of tuna and other commercial fishes. Pledges by American tuna boats and canners to abandon fishing methods that kill dolphins has not stopped foreign vessels from taking their place and feeding a growing taste for tuna in other countries, the scientists said.

"The human predator has become an efficient and voracious competitor who threatens domination at all levels of the food web," warned Charles (Stormy) Mayo of the Center for Coastal Studies in Provincetown, Mass.

A third impact of fishing is even more disturbing, scientists said. It is the increasingly common "targeting" of dolphins and porpoises--netting them on purpose, as a source of relatively inexpensive protein in such impoverished countries as Peru and Sri Lanka.

Tens of thousands are taken for food each year now--a substantial increase in just a few years--and the trend is growing. Several dolphin and porpoise species, such as the beautiful freshwater beiji in China's Yangtze River and the squat little vaquita in the northern Gulf of California, already are being pushed close to extinction, scientists warned.

As the annual kill climbs--and researchers said spotty statistics indicate that it already is well over 100,000 small cetaceans annually--other species may follow them toward oblivion unless public pressure and the International Whaling Commission are brought to bear on the problem, scientists warned.

Besides the beiji and vaquita, Brownell said that cetacean populations now facing serious problems are the striped dolphin in the Mediterranean Sea, the familiar bottlenose dolphin off South Africa and the harbor porpoise along the east and west coasts of the United States, including California.

"Without immediate and significant intervention, we are going to see the loss of some species, and we are going to see it soon," Brownell told the other scientists and environmental activists who gathered for the conference.

Such warnings overwhelmed small slivers of good news also presented at the conference, such as an encouraging report that gray whales, the species most often spotted by California whale-watchers, are growing in numbers. Brownell said that in the last three decades the worldwide catch of whales has fallen about 99%, to 669 last year.

Coincidentally, however, incomplete and anecdotal data indicate that the worldwide slaughter of smaller cetaceans has grown dramatically as commercial fishing technologies have evolved and Third World economies have declined.

High seas drift nets, miles-long webs strung across the open ocean to snare whatever is unlucky enough to encounter them, have been used for only about a decade, Brownell said. But their devastating impact on cetaceans, as well as many other species, already is being felt.

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