California's disappearing sea snails carry a grim climate warning

The red abalone is dying off as its food source—the California kelp forests—are decimated. Experts fear the die-off may be a sign of what’s to come.

California's disappearing sea snails carry a grim climate warning

The red abalone is dying off as its food source—the California kelp forests—are decimated. Experts fear the die-off may be a sign of what’s to come.

Many people have never eaten—or even heard of—red abalone, a species of sea snail that lives suctioned onto boulders and feeds on the lush kelp forests of Northern California. Abalone is a much-sought-after delicacy with a sweet, delicate flavor similar to a sea scallop, say those who’ve tried it.

“For people who think they don’t like fish…it’s amazing to see their eyes just sparkle when they take a bite and go ‘this is absolutely incredible,’” says Joe Cresalia, a recreational diver who lives just north of San Francisco. “And you know before they took the bite, they were almost afraid to take a bite.”

But as marine heat waves, ocean acidification, habitat loss, and overfishing shrink the red abalone fishery, the sweet delicacy is at risk of permanently losing its food source: the kelp forests.

“There’s a hole in our lives the size of a really good-sized abalone. We miss that,” says Cresalia.

Human influence takes a toll

The abalone was first harvested by the Native Americans, and later popularized when the first abalone fishery was established in the early 20th century. The fishery reached peak popularity during the 1950s and 1960s. Commercial fishers as well as divers from around the world traveled to the California coast to dive into lush kelp forests and pry snails off their rocks.

By 1997, too few snails remained to support commercial catches, and the fishery was closed. Only recreational divers like Cresalia were permitted to catch abalone.

Theoretically, that closure should have allowed the stressed populations to recover. They might have, were California’s oceans not quietly changing.

“Abalone are very much an indicator of the health of the kelp forest. They’re the canary in the coal mine for us because they’re very sensitive to any changes in food abundance,” says Laura Rodgers-Bennett of the California Department of Fish and wildlife. “They’re not able to switch over and eat meat or other kinds of tissues, so when their numbers go down, we know there’s something wrong in the kelp forest.”

A disastrous chain of events

Like a line of falling dominoes, a series of events led to intense pressure on abalone populations.

In 2011, a toxic algal bloom off the Sonoma coast killed off many of the local marine invertebrates, including abalone. Then came the sea star wasting disease of 2013, which got rid of many of the predatory sea stars responsible for keeping sea urchin populations under control.

Joe Gaydos, science director at UC Davis, told NPR: “What we think is that the warm water anomalies made these starfish more susceptible to the disease that was already out there.”

The sea-star die-off then triggered a purple sea urchin explosion. With no predators in sight, these echinoderms were able to reproduce quickly and with their ravenous appetite, they quickly decimated the kelp forests, leaving the abalone starving in their wake.

Then came the blob.

From 2014 to 2016, a marine heat wave now referred to as the blob formed off the coast of British Columbia and spread as far south as Northern California. (Read more about the blob that cooked the Pacific.) By 2016, the kelp forests were nearly gone.

“No wind means no mixing, and that fall [of 2013] had an incredible period of fair weather. They had no storms,” says Nate Mantua, a research scientist at NOAA. “The ocean did not give back any of the heat that it usually gives back to the atmosphere.”

The blob, according to a study released by Mantua in January of 2018, was caused by a number of natural drivers, but made worse by climate change.

Along with the other factors, the blob reached California and mixed with El Niño waters. El Niño happens every two to five years when East to West tradewinds weaken and then shift eastward, reducing the upwelling of cold water. This warm, nutrient-poor environment from the blob and El Niño was unlivable for whatever kelp wasn’t ravaged by the sea urchins. And as the kelp forests disappeared, the abalone began to die.

An uncertain future

In 2017 the California Fish and Game Commission decided to close the recreational fishery for the 2018 season due to “ongoing extreme environmental conditions.” After reassessing the population in 2018 and finding deep-water abalone all but gone, the commission decided to keep the fishery closed through 2021.

Katie Sowul, lead diver from the department of fish and wildlife, says after spending over 250 cumulative hours under water they didn’t see any improvements in the abalone populations on the coastline. If anything they saw more declines.

“We’re finding [empty] shells…at this point actually we’re almost not even finding shells anymore. We’re just not seeing a lot of abalone,” Sowul says.

Tourists, divers, and fishers visiting the red abalone fishery are estimated to have pumped 44 million dollars into the region’s economy annually. Without them, locals say the region has changed.

April 1 used to signal the beginning of a busy abalone fishing season.

Now, “April 1 comes and goes, whereas before you could see the influx of the people that were going diving,” says Chris Brians, a resident of Mendocino County.

If environmental conditions don’t change, it’s unclear if the bull kelp will be able to rebound. And if the kelp doesn’t come back, the abalone loses its food source.

Rodgers-Bennett cautions, “As the globe warms, we’re going to have more marine heat waves. We’re going to have longer duration heat waves and they’re going to be broader geographic extent. And so I think this is really giving us an inkling of what is to come.”