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BODEGA BAY — The stacks of white, water-filled troughs in a small building at the UC Davis Bodega Marine Laboratory offer a bright spot in a landscape of often-grim news about California’s marine environment.

Roughly 2,000 tiny white abalone almost a year into life here represent the promise that an all-but-extinct sea mollusk might survive.

The product of a 4-year-old program that began with 18 wild white abalone plucked from the ocean depths near the Channel Islands 15 years ago, these small shellfish — from pencil-point- to almond-sized — are proof that captive breeding can work. Already, descendant abalone produced over three spawning seasons in affiliated science labs across the state are nearly equal in number to those believed to remain in the wild, where they are scattered so widely they no longer reproduce.

But with greater success in the lab each season, and a new round of spawning planned in early March, scientists in the program say they are just a few years away from beginning to test the survival of the young abalone out at sea, in hopes of eventually restoring some portion of the wild population.

“We may not bring it back anywhere close to what it was,” said Gary Cherr, director of the Bodega Marine Lab and principal investigator for the white abalone captive breeding program. “But if we can establish some self-sustaining populations up and down the coast … that would be a first. That would be really remarkable.”

Unlike their more abundant cousins, the red abalone — which have faced challenges, though their recreational harvest is still permitted off the North Coast — white abalone have existed mainly south of Point Conception, near Santa Barbara, in deep, cold water.

One of five abalone species, they are not white at all, but are considered the tenderest, most delectable of the species, and in 2001 became the first marine invertebrate to be listed under the Endangered Species Act, primarily due to overfishing, scientists said.

More than 280 tons of white abalone were harvested in the 1970s, according to the National Oceanic and Atmospheric Administration. By the late 1990s, the species’ numbers had plummeted.

Recognition of the dire status came so late that it prevented much research on white abalone habits in the wild, reproductive and otherwise.

When a crew of scientists went out in 2000 to collect some for breeding, they deployed a remote-operated vehicle with a mounted camera to search the deep, rocky reefs, targeting “the hottest spots we knew about,” said Laura Rogers-Bennett, who participated and remains a program leader. It took two boats a week to find 18 abalone.

“The picture really has not changed since 2001,” Rogers-Bennett said, adding that a 14 percent mortality rate and inability to reproduce means the wild population is projected to drop below 1,000 in about a decade, give or take a few years. “That’s really a very low number.”

The wild white abalone population is on a downhill slide because abalone are “broadcast spawners” — meaning they release sperm and eggs into the water around them — and therefore rely much on density to successfully reproduce.

“There’s probably a few thousand left in the wild,” said Kristin Aquilino, a post-doctoral student who manages the breeding program. “But because they’re so far apart, they’re effectively sterile. Their population could be effectively extinct already.”

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But their habitat, while subject to some of the broader problems facing ocean environments, including pollution, acidification and falling oxygen levels, is essentially intact, providing hope that those bred in a controlled setting could survive once introduced to the ocean floor.

Scientists who first bred those collected in the wild early last decade took guidance from commercial red abalone farmers and met with initial success, producing more than 100,000 juveniles in 2001 and 2003, Aquilino said.

But a bacterial disease called withering foot syndrome that’s activated by warm water tore through the populations of young, wiping them out for the most part, she said.

The program headquarters were moved to the Bodega Marine Lab in part because its colder water was free from the bacteria, which has declined in recent years in any case, Cherr said, because of a virus that’s caused it to wane. But the lab also created protocols to prevent infection, using in-house expertise that brought the program north.

White abalone have a 35- to 40-year lifespan, and about 50 from that first captive-bred generation survive. They’re used as brood stock at the Bodega lab and four other partner labs, located at UC Santa Barbara, the Aquarium of the Pacific in Long Beach, the Cabrillo Marine Aquarium in San Pedro, and the Santa Barbara Museum of Natural History Sea Center. The effort is funded by the National Oceanic and Atmospheric Administration to the tune of about $70,000 a year, Cherr said.

A federal permit secured in 2011 allowed the first round of spawning in 2012, resulting in 12 survivors among the different labs. There were about 120 the next year, and last year saw a surviving class of up to 2,500. They have not been individually counted because of the setup in which they’re kept, with clear, UV-treated water bathing diatom-covered tiles scattered with kelp and a red, protein-rich seaweed called dulse — foods that collectively fulfill the abalone’s dietary needs from the delicate larval stage to when they become juvenile shellfish.

Spawning season typically runs from late winter to early spring. Its triggers remain something of a mystery, Aquilino said.

Researchers are manipulating variables like lighting and temperature to see if they can increase the productivity of the mollusks, especially those in Bodega Bay. They jokingly played Barry White music for the first few years, until Aquilino had enough and banned it last year.

Looking forward to the day of a wild release, they have placed protected cagelike traps at four sites offshore from Southern California to collect algae and develop reeflike habitats. A couple years from now, young abalone could be planted in the makeshift homes, with scientists monitoring their status.

“The hope is that we can put tens to hundreds of thousands of them out in the wild each year,” Aquilino said. “That’s what we really need to do to save the species.”

You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.

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