Wildfires and flooding trigger black abalone rescue effort

black abalone rescue
Black abalone along the Central Coast are being buried by sediment plumes caused by a combination of wildfires and spring floods. Scientists have launched an effort to capture the mollusks until living conditions improve in their shoreline habitats. Image: courtesy Nathaniel Fletcher

By Kathleen Wong, UC Natural Reserve System

The surf that breaks across Big Sur’s rocky shores obscure one of California’s most storied residents—the black abalone. Ensconced in an ovoid shell the exact blackish green of beach cobbles, this marine mollusk is nearly indistinguishable from the rocky intertidal reefs and boulders on which it lives.

The black abalone was once a major food source for California’s first peoples. Growing up to 8 inches long, the abalone’s muscular foot yields a hearty meal. Discarded shells by the thousands fill the middens of coastal tribes, which also used the pearlescent interiors as decorations.

A craze for abalone in the twentieth century, followed by a withering disease, drove the snail to near extinction in Southern California. Haliotis cracherodii was added to the federal endangered species list in 2009. The mollusk’s remaining stronghold has been the Central Coast, from southern Big Sur to San Francisco Bay.

But this year, fire and flooding have threatened to transform Big Sur into a black abalone graveyard. Local trees and brush, burnt to a crisp, were no longer able to hold the soil of the steep Santa Lucia mountains in place. When an atmospheric river hit the area in late January, millions of tons of sediments suspended in runoff poured into the ocean. The deluge buried some intertidal areas in five to ten feet of rock and sediments, entombing perhaps thousands of abalone in the process.

black abalone rescue
To find black abalone, scientists must peer under rocky ledges and poke their hands between piled boulders requires, all the while bracing themselves against sharp limpet shells and slippery strands of marine algae. Image: courtesy Nathaniel Fletcher

Researchers to the rescue

Luckily, a cadre of marine scientists from UC Santa Cruz is now riding to the rescue. Led by Wendy Bragg, a graduate student in the joint laboratory of professors Peter Raimondi and Mark Carr, the team includes 10 researchers plus some volunteers.)

Among them is associate research specialist Nate Fletcher. “We’re actually digging abalone out of some of the sediment, trying to get under there and finding abalone that are completely buried but still alive. It’s been a very busy few months.”

Normally, Fletcher monitors the health of rocky intertidal areas from Alaska to Baja California as part of the MARINe research consortium. But the team pivoted to damage control after the conflagrations. “Since black abalone are endangered, we wanted to do something to help them.”

The team has been bracing for a black abalone emergency since the Dolan Fire scorched Big Sur last September. Before the rains began, the team surveyed shorelines adjacent to burned watersheds to get good estimates of current abalone populations. That data indicated where they might want to direct their efforts after a major storm.

black abalone rescue
A stitched mosaic of images from a drone flight over nearshore black abalone habitat. Comparing images taken at intervals of several weeks reveals the movement of sediment plumes, enabling scientists to swoop in and rescue abalone threatened by sediment suffocation. Image: courtesy Nathaniel Fletcher

Guidance from drone data

Since early February, the group has been conducting drone flyovers of the abalone’s intertidal habitats. The drone they’ve been deploying is on loan from the California Heartbeat Initiative, which has been surveying post-burn areas at multiple UC Natural Reserves. When the photos are stitched together, they provide an eagle’s eye view of where plumes of sediment area headed.

“We’re using the drone to track where the sediment is moving from these outflows. As the sediment spreads up and down the coast, we can see the sediment fronts as they move through the habitat,” Fletcher says. “That can inform our decision of whether or not to remove those resident abalone before the sediment gets to them.”

“We’ll be using the drones to do monthly flights of these sites to track the sediment. And then there’s a lot of sediment that’s moving into good habitat and we’ll come in and try to rescue individuals to keep them alive. Once we get into the dry season, then debris flows are less of a concern,” Fletcher says, though moving sediments may remain a problem.

black abalone rescue
The MARINe team must do a lot of scrambling across jagged rocks and slippery algae in order to conduct surveys of intertidal habitat. Image: courtesy Nathaniel Fletcher

Pulling snails from the surf

Rescuing abalone in jeopardy is an arduous business. It involves locating an animal that looks exactly like a cobble and lives in a wilderness of rocks doused by tides.

“They blend in, and they’re deep in cracks and under boulders. We’re crawling underneath rocks and using flashlights to find them,” Fletcher says.

Once an abalone is in his sights, Fletcher must pry it off its resting spot rapidly enough to prevent it from clamping down, but also gently to avoid causing injury. The task requires speed, skill, and an admirable imperviousness to cold.

Even if an ab is buried, it may still be alive. “They can survive for awhile, especially if the sediments are not super fine and enough water flow and oxygen can get in,” Fletcher says.

To date, the scientists have managed to rescue about 200 abalone from three heavily impacted locations. He estimates that this represents perhaps 5 percent of the population at these sites—not much, but significantly better than letting the species go extinct across a swath of their best habitat.

The rescued abalone are deposited in aquarium tanks within a secure facility. There, the snails will be fed algae and carefully monitored until their habitats are no longer in danger of smothering. “Later we can put them back at the sites where they came from, or transplant them to new sites,” Fletcher says.

Taking black abalone into the lab could generate other benefits as well. These include the opportunity to launch a culturing program, and developing methods to tag and track the survival of individuals over time.

An earlier mission

This year isn’t the first time the researchers have intervened to save the endangered mollusks. In 2017 a giant landslide obliterated a long section of State Route 1 between Carmel and Lucia. The scientists removed an estimated 5 to 10 percent of black abalone from sites around that area. The rescued animals were eventually moved to another area offering conditions healthy for abalone.

Rescue logistics for 2020 and 2021, however, proved far more complicated. The pandemic meant each member of the team had to drive separate cars to every site. Then merely driving to sites became a headache after a January storm triggered a slide at Rat Creek. The event was large enough to shut down Highway 1 about 45 miles south of Carmel.

“We actually had one day where we were working on the north side of Rat Creek. We drove all the way around to the south side through Cambria. It took us five hours to get around,” Fletcher says.

Despite these additional headaches, Fletcher says the work has been more than worthwhile. “If we didn’t do this work, the population in some areas could otherwise completely be wiped out.”

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