Scientists celebrating breakthrough in race to save endangered white abalone at UC Davis Bodega Marine Lab

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Scientists are celebrating a population boom among endangered white abalone being raised at the UC Davis Bodega Marine Lab as they approach the day they can begin introducing captive-bred sea snails into their natural ocean habitat — perhaps later this year or next.

The good news comes mainly as a result of the reproductive success of a single champion egg producer who, with her supporting cast, recently contributed about 12 million new larval specimens to the program, lab scientists said.

The fecundity of the abalone tagged Green 312 is all the more significant because she is among nine mollusks carefully hunted and collected from the wild over the past two years under a special federal permit allowing for added genetic diversity in the captive breeding program.

“It’s monumental for this program and for the future of this species,” Program Director Kristin Aquilino said.

Large-scale reproduction is critical both because of the high mortality rate among larvae, as they transition through life stages, and because so many mature abalones are needed to restock the species — the first marine invertebrate listed as endangered under the federal Endangered Species Act in 2001.

But though researchers have resorted to mood music, timed lights and even a “romantic love potion” that’s hydrogen-peroxide based, they have found it a struggle to unlock the key to the white abalone’s ardor.

Scientists managed to accumulate about 100,000 juvenile abalones between 2001 and 2003, when the captive breeding program first got started in Southern California with 18 wild adults plucked from the ocean near the Channel Islands.

But the majority were lost to a bacterial disease that was able to thrive in the region’s warm water before they could go far with it.

The clean, cold waters of Bodega Bay and local expertise on invertebrate health identified the UC Davis marine lab as a natural alternative site for the relocated program. It was finally underway in 2011, housed primarily in an artificially lit room filled with tanks and trays that are home to different age classes of juvenile white abalone and the mature mollusks from which they sprang.

But between 2003 and 2012 there was no successful reproduction, slowing the prospect of the species’ recovery even as scientists developed the plan under which they planned to pursue it.

Between 2012 and 2017, using the original brood stock now divided between partnering institutions, seasonal spawning sessions began producing enough young to establish an inventory of young abalone. But none of the females were producing the number of eggs even close to what they should be, Aquilino said.

Green 312 had already shown herself to be a prolific spawner when she produced eggs on the boat at the time she was collected in 2017 and again four weeks later in the lab, Aquilino said.

Last week she produced more than 20 million eggs — so many that, combined with surviving embryos from other spawning abalone, Aquilino and her team had to farm out 10.5 million larvae to be raised by nine partnering institutions and nonprofits in the White Abalone Recovery Consortium. They still had enough to keep 1.5 million in the Bodega Bay lab.

“Her contribution to the future of her species is really critical, and her spawning really does represent the future of her species,” Aquilino said of white abalone G 312.

Fished to near extinction largely in the 1970s, the number of white abalone in the wild is estimated to be as low as 1,600 to 2,500 by federal scientists, though UC Davis principal scientist Laura Rogers-Bennett said it could be 4,000 to 5,000.

Either way, it’s a tiny fraction of the millions that once occupied deep waters offshore Southern California and Baja. Their survival was shielded by the relative ease of harvesting red, pink, green and black abalone cousins from shallower waters.

But once those commercial stocks were depleted, abalone eaters discovered the whites — the tenderest, most succulent of all — and they were quickly decimated, too, making it onto the Endangered Species List in 2001.

The problem for all the abalone species is that they have to be nearby one another to reproduce. They are broadcast spawners, meaning male and female alike emit a cloud of gametes into the water, and the reproductive cells either get close enough to create the foundation for life or they don’t.

White abalone are so few and far between that they are effectively sterile in the wild, Aquilino said, thus making human intervention a necessity if the species is to survive.

But unlike many other endangered species, white abalone habitat is largely intact, so “if we create enough abalone and get them out there, we can save the species,” Aquilino said. Though still subject to the global marine problems of climate change and acidification, there is at least a chance of recovery, she said.

Those stressors are one reason scientists in the program were so eager to bring more wild specimen into the brood stock, said Rogers-Bennett.

“The more genetically diverse the population, the more they will be able to withstand temperature changes and other environmental challenges,” she said.

Scientists in the program already have been working for years to test the best way to reintroduce the white abalone, using cinder block structures to serve as artificial reefs to give them cover while they acclimate, scoping out locations in marine protected areas and using red abalone as surrogates to see how well they do. The abalone would be tagged so they could be monitored and assessed.

Rogers-Bennett said program leaders are hoping for new funding sources to get to the next steps but are ready to begin planning.

“The whole program is really poised now to take the animals we’ve created and put them out in the ocean,” she said, “so we’re at this really exciting point, where all this hard work that we’ve been doing for years and years, we’re just on the verge of actually putting more white abalone out into the ocean.”

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.

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