Environment & Science

White abalone aren't recovering even when the fishing pressure's off, say federal scientists

White abalone has been protected federally and in California for more than a decade, but it's still not recovering.
White abalone has been protected federally and in California for more than a decade, but it's still not recovering.
NOAA's Southwest Fisheries Science Center/FRD

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Federal biologists say a species of sea snail once plentiful from Santa Barbara to Baja Mexico has dwindled so far that it may not come back.

Older Southern Californians can remember white abalone in shallow nearshore waters 40 years ago. Abalone shells still line windowsills in coastal houses, left over from when restaurants pounded the mollusk's meat and fried it into a regional delicacy.

Legal harvest peaked in 1972, at 143,000 pounds. Then the fishery busted. California made it illegal to hunt white abalone 16 years ago.

“We were hoping that, in the absence of fishing pressure, that these populations would naturally recover,” says biologist Kevin Stierhoff.

Those hopes are now dashed. Stierhoff works for the Southwest Fisheries Science Center, a part of the National Oceanic and Atmospheric Administration in La Jolla. He’s the author of a new federal survey published in Biological Conservation, the fourth in the past decade finding critically small populations of white abalone. He says the remaining abalone may be too far apart to thrive.

“It’s important for males and females to be close to one another, and when I say that, I mean 2 to 3 meters,” he says.

That’s because abalone reproduce by broadcasting sperm and eggs in the water outside their bodies. The closer abalone are for that transaction, the better. But scientists estimate a few thousand white abalone where divers once pulled up several hundreds of thousands a year.

“So the individuals that we see are truly that; they’re individuals,” Stierhoff says. “We’re not seeing many groups of abalone. And they’re far enough apart from one another that even if they are trying to reproduce they’re not close enough so that successful fertilization can take place.”

With every additional survey, Stierhoff says, it seems less likely that juvenile abalones are simply eluding detection. With every passing year, recovery efforts have turned their attention to boosting reproduction.

Working with the California Department of Fish & Game, the federal government is funding teams at UC Davis, UC Santa Barbara, the Aquarium of the Pacific and Cabrillo Aquarium trying to cultivate abalone in labs. At the Aquarium of the Pacific, for example, federally-provided white abalone have been on-site for a little more than a year, says Perry Hampton, the facility’s vice president for husbandry. But initial breeding efforts have focused on red abalone, Hampton says, another threatened population in California.

The three-year grant supporting that work will soon run out. Stierhoff says many of the abalone in the wild are nearing the end of their natural 30-35 year lifespan. “So that’s the new sense of urgency that we have,” he says. “We need to be successful in our other efforts more so now than ever if this population is not going to truly go extinct.”

State fish and game officials say remaining abalone in California waters are pretty much out of reach of most scuba divers, so poaching is a shrinking concern. Mexico controls Baja California waters and data for about half the white abalone’s territory. Federal scientists say they still hope to work more closely with the Mexican government to bring abalone back.

"We are at a point where a successful breeding program is critical to the survival of the species," says Melissa Neuman, NOAA’s recovery coordinator for white abalone. At this point, Neuman says, human intervention is the only thing standing between white abalone and extinction.