Biologists, Fishermen Disagree on Abalone Illness : Fishing: A mystery disease that devastated the local population of black abalone could be afflicting other varieties, scientists say. But commercial divers claim they are crying wolf.

VENTURA —  A mysterious plague that has nearly wiped out one type of abalone in the Channel Islands may be spreading to other varieties of the marine mollusk--a scenario that could jeopardize commercial abalone fishing in California, state and federal wildlife experts say.

Marine biologists at the Channel Islands National Park and the California Department of Fish and Game say they suspect that “withering syndrome,” an ailment of unknown origin that has devastated the population of black abalone in Southern California waters, is beginning to appear in red abalone.

That theory has provoked an angry reaction from commercial abalone divers, who charge that the scientists are crying wolf. They insist that the red abalone population on which they depend for their livelihood is healthier than it has been in years.

The future of California’s $2.8-million annual commercial abalone fishery may depend upon which side is right.

Scientists as yet have no proof that the syndrome has spread. But a recent surge in reports of the ailment in Channel Islands red abalone is cause for alarm, said marine biologist Pete Haaker of the state Department of Fish and Game in Long Beach.

Signs of withering syndrome have also been reported in the less common pink and green varieties, Haaker said.

“We’ve been receiving reports from divers that they’ve been finding areas with lots of fresh shells, which is an indication of unusual mortality,” Haaker said. “When the public starts letting us know that there’s a problem, that’s a pretty good indication that we do indeed have a problem.”

Long valued for its tasty meat and the mother-of-pearl interior of its shell, the California abalone is already scarce.

The Channel Islands black abalone population--once the most widely harvested of the five local species--has declined by more than 90% since withering syndrome appeared in 1985. Decades of massive harvesting by commercial divers, exposure to man-made pollution, and an increase in predators such as sea otters have taken a severe toll on the pink, green and white varieties.

Although the red abalone population has also declined over the years, it is the only type present in large enough numbers to support a commercial fishery. Red abalone accounted for 87% of the 519,373 pounds of abalone caught in California in 1992, according to Fish and Game statistics.

But some local fishermen dismiss concerns about red abalone as unfounded and politically motivated.

“If they say that withering foot disease is in the reds, they’re lying,” said commercial diver Mark Rosatti, who has been catching abalone for 25 years. “We know what’s going on down there, whereas those guys are just guessing.”

Rosatti, who dives the Channel Islands from his base at Ventura Harbor, accused environmental “daisy-sniffers” of trying to use scare tactics to prohibit divers from working the islands out of a desire to “make Southern California into their own playground.”

A clearer picture may soon be at hand. In October, the Department of Fish and Game collected a number of weakened red abalones from waters off San Miguel Island, the prime hunting ground for commercial divers. A fish pathologist at the Fish and Game Disease Laboratory in Rancho Cordova, near Sacramento, is examining the mollusks for symptoms of the deadly ailment.

Commercial fisherman John Colgate, president of the California Abalone Assn., a divers organization in Santa Barbara, said he fears that publicizing scientists’ charges might lead consumers to falsely believe that the mollusk is unsafe to eat, which could drive down the price that the 125 commercial divers in California get for red abalone at market.

Scientists and fishermen alike are frustrated by the fact that eight years after the first dead and dying black abalones were discovered on the south side of Santa Cruz Island, the cause of withering syndrome still has experts stumped.

Researchers do know that withering syndrome attacks an abalone’s foot--the fleshy part outside the shell--causing the mollusk to weaken and die within a matter of weeks.

But the presence of a shrunken foot alone does not necessarily mean that an abalone has the ailment, said Gary Davis, a marine biologist with the National Park Service at the Channel Islands.

Abalone tend to weaken and shrivel up no matter how they die, whether the cause is starvation, pollution or the puzzling syndrome, he said.

Early theories of the source of withering syndrome ranged from increased ocean pollution to the severe El Nino conditions of the early 1980s, which warmed ocean waters and destroyed some of the kelp beds on which abalones feed. But a UC Santa Barbara study published last June discounted those explanations and concluded that an infectious disease was the most likely culprit.

“That’s the good news,” said Armand Kuris, the marine biologist who co-authored the study. “The bad news is that we don’t yet have a causative agent identified.”

On Aug. 1, state officials banned the taking of black abalone from California waters for at least the next year and a half in an attempt to preserve the few that are resistant to the syndrome.