Aquilino, a scientist at the University of California, Davis, knows that expectations are meaningless. She has led the school's captive breeding program to bring the marine mollusk back from the brink of extinction.
In June of last year, she and her colleagues drove snails from Davis to the Cabrillo Marine Aquarium in Los Angeles. This was the largest spawning attempt of white abalone to date, with others being dropped off at labs and aquariums around Southern California. She tried to get them in the mood with a mixture of water and hydrogen peroxide, but they didn't produce any eggs or sperm. Dr. Aquilino called it off after four hours. Attempts at the other sites also failed.
She said that there is a lot of human effort involved, but there is no way they will be able to create something today.
The sea snails are hanging on by a slimy thread after fishermen deplete 99 percent of white abalone from the wild in the 1970s. Dr. Aquilino says it's still a guessing game how many of these and other aquatic snails will be brought to a lab.
A study published Thursday in the journal Frontiers in Marine Science offers an improved tool for determining which abalone will be reproductive. The technique could raise the prospects of successful captive breeding efforts and help restore the species in the wild.
If we can use this method, it could make a big difference and we might be able to strategically target animals. Getting animals to start spawning is the most important point in the process of recovering them.
For Dr. Aquilino, the method offers some hope.
She said that when she saw the images of her kids, she saw the future of her family.
The west coast of North America has historically been home to seven species of sea snails. The animals help the environment by maintaining forests, feeding animals and improving the health of the reefs.
Over the course of the 20th century, divers and fishermen decimated several species of abalone. The black and pinto abalones in the northern Pacific suffered from overharvesting and habitat degradation. In the wild, abalone snails are terrible at long-distance relationships because they must be within proximity of each other to reproduce. Scientists realized they needed to intervene when there were so few of the species left.
Producing them in captivity is a big challenge. There aren't clear clues when they're ready to reproduce. Researchers have traditionally inspected the snails visually by removing whatever surface they are suctioned to, then looking for a bulge between their sticky feet and shell, where the animal's gonad is below the skin. The scientists give the animal a score based on how large the gonad is.
Josh Bouma, the program director of the Restoration Fund in Washington State, who heads the captive breeding program for the pinto abalone, said that that kind of information gives you an idea of whether or not the animal may be able to reproduce.
It can be vastly inaccurate to take a visual exam. The score can be misleading if the snail just had a huge meal. It would kill the snail if researchers took a more accurate tissue sample. Handling them in any way, including popping them from their aquarium tanks, is enough to stress them out.
It is not possible to see it with the naked eye.
The idea of using Ultrasonics on snails came about in 2019. Jackson Gross, an aquaculture specialist at the University of California, Davis, had used the technology to study the reproductive habits of fin fish. He stumbled across a video on the internet of a vet sliding a probe on the bottom of a snail. If it worked for land snails, wouldn't it work for sea snails as well?
Sara Boles, a researcher working with Dr. Gross, discovered a way to use the device on the abalone without taking them out of their tanks. The images of their swollen or flaccid gonads were quickly produced on a laptop appended to the probe.
In the new study, Dr. Boles and her colleagues scored the thickness of their gonads on a scale of 1 to 5 to determine which ones are likely to hatch. The stomach appears as a dark, cone-shaped item, and the slightly lighter gonad surrounds it.
These images can be used to score animals, but Dr. Gross and his colleagues want to verify if gonad thickness is related to reproductive success.
Dr. Boles has been helping Dr. Aquilino with her breeding efforts. After Dr. Aquilino visually scored the animals, Dr. Boles brought the ultrasound to her lab.
Five of the eight white abalone that Dr. Boles rated highest spawned, as did some of the snails with slightly lower ratings. The method helps researchers revise their methods of assessing which abalone are most ready to reproduce.
It is another way to help ensure that we have the best of the best.
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