To Save This Tasty Sea Snail, We Must First Figure Out What Turns It On

July 26, 2017/ Jason Bittel / Conservation, Natural Resources Defense Fund, North America, Oceans, Resources, Species

Published by the Natural Resources Defense Fund

At the Bodega Marine Laboratory north of San Francisco, Kristin Aquilino is busy trying to romance a bucket of white abalone spawn. Her recipe for making more of these sea snails starts with a cloud of eggs from a female, followed by a squirt of semen from a male. It’s an intuitive process, but she double-checks her ratio under a microscope until she has around 10 to 15 sperm knocking on the door of each egg. Too few sperm in the bucket and many of the eggs will go unfertilized, a waste of precious resources. Too many sperm and the eggs could self-destruct on contact.

“Matchmaking at its finest!” writes Aquilino in an e-mail.

Aquilino is a marine biologist at the University of California, Davis, which runs the BML. She’s also in charge of the state’s captive-breeding program for white abalone, only a few thousand of which remain in the waters off Southern California.

Believe it or not, the flying spaghetti monster exterior of this 10-inch-long marine snail gives way to a fillet of tender, white meat that North American coastal communities have enjoyed for 10,000 years or more. And its tastiness is precisely what has nearly wiped the white abalone off the face of the earth.

Even though there are also green, red, and black abalone, none of these gastropods is thought to be as yummy as the whites, which supposedly taste like calamari. Gustatory desire reached a tipping point in the early 1970s, when fishermen were hauling up 143,000 pounds per year. By 1978, the catch was just 5,000 pounds. Unfortunately, we didn’t fully realize what we had done until 1997, when the National Oceanic and Atmospheric Administration halted all harvesting until the species could recover.

The abalone, though, didn’t bounce back, despite the fact that a single female can pump out as many as 10 million eggs in one go.

The problem is that abalone are broadcast spawners. Instead of actually touching each other during sex, the snails spew their sperm and eggs into the water column and hope the two meet. This DNA swap, however, is nearly impossible now. There just aren’t enough abalone left to make the connection. In fact, Aquilino says a distance of just three feet can render an abalone “effectively sterile.”

“The eggs are immobile,” says biologist Marah Hardt, author of Sex in the Sea. “They have no capacity to move, so they just drift in whatever direction the current takes them.” And even though sperm have those fun little tails, “they only have so much energy before they fizzle out.”

The National Marine Fisheries Service designated the white abalone as endangered in 2001, making it the first marine invertebrate on the Endangered Species List. Scientists whisked 18 adult white abalones into laboratories in 2004 to set up a captive-breeding population. After about a year, these abalone Adams and Eves had broadcast-spawned their way to about 100,000 juveniles. The species seemed to be saved.

Not quite. After just one year, most of those newborns fell victim to something called withering foot syndrome (WFS). This naturally occurring bacterial condition usually doesn’t cause too much trouble in the wild, unless the water gets warm for some reason—like during an El Niño event—at which point the bacteria population explodes. Once it gets inside the snails, it attacks their guts, causing them to stop feeding. After a while, the abalone falls off its rock, and either it starves to death or a predator picks it off.

For seven years, WFS annihilated most of the juvies in the lab. Meanwhile, the last few thousand white abalones in the wild, which have a maximum life span of around 35 to 40 years, were getting older and older without successfully reproducing. The hands of the extinction clock were ticking.

Fortunately, UC Davis acquired the white abalone captive-breeding permit in 2011, and a crack team of interdisciplinary scientists took over. That’s when James Moore, the director of the California Department of Fish and Wildlife’s Shellfish Health Laboratory, helped create a game-changing antibacterial wash to root out the WFS microbes. The tide then began to turn for the species.

“We had our first success here in 2012, where we created about 20 white abalone,” says Aquilino. “That’s not going to save the species, but it was a really big deal after about a decade of nothing.” The following year produced about 120 juveniles, and the year after that came a few thousand more. Fast-forward to 2017, and Aquilino says they’re looking at 23,000 young white abalones slurping around the tanks. Including the snails still alive from the past 13 years, she puts the entire captive population at around 30,000 animals, which she says is easily more than the few thousand in the Pacific.

What’s their secret? In addition to the antibacterial wash for juveniles, Aquilino and her colleagues coax the critters to release their sperm and eggs by dousing them with hydrogen peroxide. This introduces free radicals into their environment and makes them think their neighbors are spawning. The teams also rig the lights above the tanks to turn on and off at precisely the times the sun rises and sets to give the animals a sense of what season they’re in. Still, the abalone are producing only 20,000 or so offspring a year, not the hundreds of thousands that they should be able to produce.

“We’re still not really sure what exactly triggers them to be reproductive,” says Aquilino. “We think they might be missing some important environmental cues that they probably get in the wild but aren’t receiving in the sterile environment of the lab.”

Hardt says this same mating problem is at the root of conservation efforts for countless other ocean species. “Sex is how we make more,” she says. “And when it comes to fish and abalone and worms, there are just whole categories of reproduction that we have no idea about.”

The scientists now house their white abalone generations in six facilities. This helps safeguard the snails against an unforeseen disease outbreak, power outage, or other act of god (a good idea in the case of the Bodega facility, which rests atop the San Andreas Fault). “Just as you don’t want to keep all your eggs in one basket,” Aquilino says, “you don’t want to keep all of your endangered animals in one tank.”

The good news is that Aquilino and her colleagues learn a little more each year about how to properly arouse white abalone. And next summer, they hope to start planting the fruits of their labor in select locations along the California coast. With a little luck, it could be white abalone’s first Summer of Love this side of the new millennium. 

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