.Scientists Race to Rescue Endangered Black Abalone

Wendy Bragg puts her hair up with a zip tie and pulls a stopper on the outside of a large tank of seawater. A chart on the tank says it holds 40 rescued black abalone, but I can only see a few stuck to the sides.

The water drains out, mimicking low tide and exposing a few large rocks and concrete blocks at the bottom of the tank. Bragg climbs inside and reaches down to pick up a cinder block, revealing a dozen abalone that have crammed themselves into the square holes. 

They like to buddy up and sit on top of each other, she explains. The abalone spend most of their time submerged in the seawater that flows through the tanks, but “every once in a while, we get one that moves up on the shelf and decides to become a terrestrial being,” she says with a laugh, pointing to an abalone that has crept above the tank’s waterline. 

As if on cue, one of the abalone in the block she’s holding makes a break for the top side. It moves fluidly and surprisingly fast for a marine snail. Bragg gently guides it back toward the others with her hand, and sets the block back down.

Bragg is an ecology and evolutionary biology Ph.D. student at UCSC. She and a team of scientists have spent the past several months rushing to rescue endangered black abalone from landslides and debris flows along the coast of Big Sur.

She walks me through the rest of the holding center, where rescued abalone live in tanks for a few months before researchers transport them to new areas. To see the tanks, I agreed to keep the location secret, driving to a nondescript pin on a map and following Bragg the rest of the way.

Except for the sound of flowing water, the scene is quiet. “It’s kind of relaxing to be here as long as nothing is going wrong,” she says. The abalone seem content, too, as they sit waiting for hand-delivered kelp.

Withering Population

California has several species of abalone—large marine snails. These grazers feed on kelp and algae, creating habitat for other species as they go. 

For thousands of years, abalone played an important role in the heritage of several Indigenous coastal communities. Today, many people know them as a culinary delicacy and for their iridescent mother-of-pearl shells. 

Most species live submerged in rocky cracks and crevices on the reef. Only one Californian species makes its home in the intertidal zone, or the space between high and low tides: black abalone. They spend some of their day completely underwater, and some of it totally exposed to air.

The critically endangered species used to exist from halfway down Baja up to Cape Mendocino, but over-harvesting depleted the populations in Southern California by 1980. A few years later, a disease swept through, killing most of the remaining animals in the south. 

The sickness, called “withering syndrome,” prevents the abalone from digesting food. They become emaciated and eventually die.

The killer bacteria crept up the coast—likely in the warm water of El Niño events—and killed population after population of abalone.

“The disease was incredibly virulent, rapid and unrelenting,” says Peter Raimondi, a marine ecologist and evolutionary biologist at UCSC. Raimondi is heavily involved with abalone restoration efforts and leads a large-scale, long-term intertidal monitoring program called MARINe (the Multi-Agency Rocky Intertidal Network).

Researchers with MARINe routinely collect information about the species between land and sea, taking note of their numbers, sizes and health. In the ’90s, scientists noticed withering syndrome approaching the base of Monterey County. 

It doesn’t seem to have moved much since then. But the remaining healthy black abalone—most of which live in Big Sur—now face a new threat. 

Murky Future

Wildfires burned right to the water in parts of the Central Coast last summer, and scientists began to worry that winter rains could wash fire debris and loose earth into the ocean, burying vital habitat.

“We looked at where those fires were located, and they aligned with where 75% of the remaining healthy black abalone populations are,” says Bragg, who leads field efforts for the project.

Bragg joined a group of scientists from UCSC, the Monterey Bay National Marine Sanctuary, the National Marine Fisheries Service and other institutions to create a rescue plan for the worst-case scenario. 

The team compared USGS debris flow maps to watershed maps to see where debris might end up. They located access points and began surveying the black abalone and habitat where they could.

Starting in October, they took photos and GPS points, recorded numbers and sizes of abalone, and measured sediment levels. Getting a sense for the population and habitat would help them figure out losses in case disaster struck. And it did. 

“We were still working on that effort when the debris flows hit,” says Bragg. 

In late January, heavy storms and strong winds battered the Big Sur coast. More than 10 inches of rain soaked the burned areas within a few days. The subsequent landslides dramatically changed parts of the cliffy coast. The researchers’ worries had come true.

The team waited for low enough tides and drove to Big Sur access points. They scrambled down steep trails, carrying equipment for rescuing and transporting the abalone, unsure what they would find.

“Before we even walked on to the beach, in some locations, you could smell the smell of death—that things were rotting down there,” says Bragg. 

What they saw shocked them. Some areas looked so different that the scientists had trouble orienting themselves. 

“It was so much worse than anyone thought,” says Raimondi. “It was catastrophic in places.”

Sand and sediment completely covered previously rocky shorelines. Tree trunks and car-sized boulders had come crashing down the slopes, crushing everything in their paths.

The debris flows were “not just a river or a creek carrying water with some sticks in it. This is sort of like a wall of cement,” says Steve Lonhart, a research ecologist for the Monterey Bay National Marine Sanctuary who has worked on black abalone restoration efforts for over a decade.

The scientists estimate that along the Big Sur coast, tens of thousands of black abalone died. Since around 75% of the remaining populations are in that area, “you’re looking at pretty catastrophic losses for the species,” says Bragg.

Many of the surviving snails had injuries and sandblasted or broken shells from the violent event. Researchers found some of the animals stranded on rocks or patches of sand. Others were completely buried.

“It was pretty shocking to see all of the evidence of how traumatic it was,” says Bragg. 

The team jumped into rescue mode, taking extreme care to remove the black abalone. The animals don’t have a clotting factor in their blood, so if they receive a bad cut, they bleed out.

But if left behind, the abalone would likely die. “It’s not risky when you remove animals that are going to die anyway,” says Raimondi. “We think of these as the living dead, meaning they would have been dead.”

Rescue and Release

The researchers rescued around 200 black abalone over several trips to the field. They transported the animals to a holding facility and started planning when and where to rerelease them.

The group keeps the location of the rescues, releases and holding center secret, as poaching still threatens both wild and captive abalone, says Susan Wang, the black abalone recovery coordinator for the National Marine Fisheries Service. 

She recalls a case where poachers stole green abalone from a public aquarium in Southern California. 

“They were raising them to help restore green abalone populations along the coast. And they had an incident where someone broke into their facility,” she says. “We just want to make sure we’re doing everything we can to protect them from potential poaching.” 

Some 84% of the rescues have survived in their temporary home. The scientists are satisfied with the number, pointing out that several of the animals arrived injured.

“Where they were located, basically there was no way they were going to survive,” says Bragg. “So any gain is a gain. But having said that, we’ve had a really good success rate.”

Researchers weighed the animals as they arrived, collected genetic information and studied their fertility using ultrasounds.

“We’re trying to take this opportunity to grab as much data as we can, because no one has been able to collect abalone since they were listed [as endangered],” says Bragg. That happened over a decade ago. 

The group worked for months before the start of the project to obtain permission from landowners and secure permits to handle the species. 

Bragg wants to thank key funders and collaborators— which include the National Marine Sanctuary Foundation, MARINe, NOAA’s National Marine Fisheries Service (NMFS), Monterey Bay National Marine Sanctuary (MBNMS) and the California Department of Fish and Wildlife (CDFW)—noting that, “this effort would be absolutely impossible without everybody having pulled together.”

“There’s very few people who have permission to even touch them, let alone to remove, bring them into a facility and then translocate them,” says Lonhart. “There’s a massive amount of regulatory paperwork and stuff that goes along with doing anything with any endangered species.”

Turning the Tide

After a few months of waiting for the debris to clear, the group decided on a new location for one group of abalone, drove down to Big Sur and made their first release. They put 10 black abalone into the intertidal zone and spent a few days monitoring them. 

All of them survived.

In the next few months, the team will continue the releases and revisit old sites. Come fall and winter, they will watch the areas carefully for signs of additional threats.

Even without new fires, risks remain. In areas that experienced a complete burn, it could take a few years for the soil structure to recover. And because only one big storm came through the Central Coast, lots of debris still litters the burn scars. 

“It’s very likely something like this will happen next year too,” says Raimondi. Buried habitat could become a recurring threat.

“There’s a lot of evidence that suggests these atmospheric river events—where you have a lot of water coming down in very short periods of time—is going to be more normal in our changing climate of the future,” says Lonhart. 

But the scientists remain hopeful. “Seeing the resiliency of that intertidal habitat and of black abalone themselves—I think that that’s been pretty exciting,” says Lonhart.

The project might also inspire more active work in the recovery of the species. 

“We’ve been of the mindset that if we leave them alone, then they will recover. And that is true for most things,” says Raimonid. “But now, there’s an impetus to start a different approach, which is more interventionist.” 

In addition to the relocation efforts, the scientists have begun exploring the idea of breeding the animals in captivity. 

“I think it’s really important what they’re doing,” says Kristin Aquilino, lead scientist for the White Abalone Captive Breeding Program at UC Davis. “It’s a lot easier to try to save a species before it’s really on the brink than it is to try to bring it back from the brink.” 

Aquilino does not currently work with the black abalone restoration efforts, but her white abalone program might serve as a model in the future.

“We have this method to reproduce abalone in captivity where we put them in this love potion of hydrogen peroxide, and hopefully they give us whatever gametes they have,” she says. But black abalone prove harder to breed than any other Californian species.

Wang says the same, noting that she knows of only one documented success. But, “there hasn’t been as much work and focus on black abalone,” she says. “I think working together, we can really still be successful in recovering black abalone.”