White abalone are so rare that the federal government lists them as in danger of extinction. They are so stressed that they haven’t been found breeding in the wild for years.
So biologists who started a captive breeding program to save the species faced a formidable challenge: how to get the white abalone in the mood.
Call it chemistry. Call it lucky in love. But expert abalone handlers figured it out.
Start by gently scrubbing the shells with a soft-bristle brush. Then dim the lights. Next, a bath in clean, chilled water. And, finally, pour in a special potion researchers call an abalone aphrodisiac.
Success was achieved on the second try. One male and two females spawned at the same time. The progeny--6 million baby mollusks.
Not a bad performance in front of so many anxious, hovering officials. Assembled around these tanks were biologists from UC Santa Barbara, the U.S. Geological Survey, the Channel Islands National Park, California Department of Fish and Game, National Marine Fisheries Service and the Channel Islands Marine Resource Institute.
“It’s very tricky,” said Neal Hooker, a researcher at UC Santa Barbara’s Marine Biotechnology Center. “If the animals are under any stress, they won’t spawn.”
To be sure, not all 6 million of these marine snails will survive. The mortality rate is high among creatures such as the abalone, which are called broadcast spawners. But without the predators that exist in the ocean, scientists hope to end up with at least 10,000 adults.
At this point, scientists believe they still have about 100,000 of the tiny mollusks grazing on an underwater prairie of algae in temperature-controlled tanks in Port Hueneme. It’s hard to be sure how many are actually there. At a couple of millimeters wide, they are too tiny to count.
The plan is to raise the young abalone in captivity for the next four years. At that point, their shells will measure at least 4 inches across, a size at which they will be able to resist most predators.
Then, over the next 10 years, about 1,000 of them will be released into the wild each year. That’s the plan, at least for now.
The white abalone needs the help because its population has been devastated just like its red, pink, green and black abalone cousins. The problem in every case has been excessive hunting, which began in 1942 and ended in 1997, when California authorities banned commercial harvest of the mollusks.
The white abalone, the deepest dwelling of the species, were plundered from 1969 to 1982, when most other types were picked clean. Once numbering 4.24 million, their population has plunged to fewer than 2,300 today.
State officials tried to preserve abalone by limiting the catch to larger animals, leaving the smaller ones to reproduce. But the remaining animals were scattered so far apart that they cannot find each other to spawn.
Over the years, scientists have tried to intervene. They have collected thousands of abalone and congregated them on one reef so their eggs and sperm would connect.
But when biologists returned to these sites, they would find that poachers had taken every last one.
Such a strategy was considered too risky for white abalone, given how few remain in the wild.
So the biologists turned to captive breeding, hoping to produce enough that the species can begin to recover. Learning from earlier mistakes, they don’t want to release the white abalone when they are too young or too small.
In previous experiments with other types of abalone, biologists have placed dime-size abalone on the ocean bottom.
They found that octopuses drill holes in their shells. Lobsters and crabs pull them off the rocks. Various species of rockfish gobble them whole and regurgitate their shells.
“They’re like popcorn at that size,” said Gary Davis, an abalone expert and biologist for the Channel Islands National Park. “Everyone is eating the little abalone.”
But when they get to be 4 inches, Davis said, “they’re adults, and their only predators are giant sea bass, angel sharks, bat rays--and man.”
To foil the white abalone’s most insatiable predator, scientists plan to plant them deep enough--below 100 feet--to be out of reach of the typical poacher.
The plans of the captive breeding program could change, however, now that the National Marine Fisheries Service has enrolled the white abalone on its endangered species list.
With the listing, which came in May, “it instantly becomes much more difficult to do research,” said Kevin Lafferty, a marine ecologist for the U.S. Geological Survey. “It’s an additional layer of protection, but ironically it makes it harder for us to work with them to help them recover.”
The first hurdle was the paperwork. When it comes to endangered species, federal wildlife officials are accustomed to dealing with larger animals, say condors or cougars. They like to track each animal and require permits for anyone who handles one.
So when the abalone team explained that the breeding program produced millions of the tiny mollusks, the officials weren’t sure how to figure that into their standard forms.
“It was a whole new concept,” Davis said. “They asked, ‘How are you going to keep track of them?’ We said, ‘Maybe we don’t need to keep track of every one.’ ”
The government is coming around on how to handle the first marine invertebrate to hit the endangered list. But other issues remain. One is to make sure whatever abalone are released into the wild have sufficient genetic diversity.
The breeding program has about 15 adults in captivity, all collected from the waters around Santa Catalina Island. Scientists figure they will need about 200 abalone from different areas so that a genetically healthy stock can regain a foothold.
But first the team needed to coax white abalone to reproduce in captivity. Unlike red abalone, whites are fussy. They only spawn once a year. In fact, the current experiment was the first time that white abalone had been induced to spawn in more than 20 years.
A Love Potion
The team points to UC Santa Barbara molecular biologist Dan Morse for pioneering work in abalone biochemistry. He figured out that a solution of diluted hydrogen peroxide added at the right moment can stimulate abalone hormones so they spawn on command.
The actual deed is left up to UCSB’s Hooker, a master abalone handler with 25 years of experience with the spiral-shelled mollusks.
Timing is everything, of course. The only way to determine whether males and females are ready is to lift them off the tank and peek under their shells.
That’s not all that easy. These gastropods (literally: stomach foot) have powerful muscles designed to keep all but the most determined predators from prying them off rocks. Furthermore, their blood doesn’t have coagulants like mammals, so they can easily bleed to death from a careless cut.
But Hooker is renowned for his easy touch with a spatula and his other winning ways with abalone, such as dimming the lights and chilling the water to help them relax, feel more at home.
“You have to have the larvae very clean,” Hooker said. “When I spawn the animals, I clean their shells so they don’t get any debris mixing with sperm and eggs. I let them sit in 15-degree [Celsius, about 60 degrees Fahrenheit] water for an hour before I adjust the pH and add hydrogen peroxide. That’s the whole trick.”