Earth_Island_Journal_-_Spring_2020

EARTH ISLAND JOURNAL • SPRING 2020 21

abalone had already been listed as federally endangered, and

pinto, pink, and green abalone had been listed as “species

of concern.” Flat abalone populations contracted to the

point where the species was no longer common in California

waters, and red abalone became more abundant on abalone

aquaculture farms than in the wild ocean.

D

AY TO N EXPLAINS THAT, fundamentally, abalone faced

a population density problem. As “broadcast spawn-

ers” — animals that breed by casting sperm and eggs out into

the sea — abalone need to be within mere meters of each

other for successful fertilization. Intense harvesting broke up

the aggregations of abalone that were key to their reproduc-

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tively sterile given the ever-widening distance between mates.

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Octopus — another major source of abalone mortality — have

proliferated in the absence of predators. Diseases, too, such as

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populations. Moreover, carpets of purple urchins, sometimes

with up to 100 individuals per square meter, eat every kelp in

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from which to exclude them. “I’m worried about the kelps,”

Dayton says. “One reason the abalone and everyone are in

trouble is there’s no food.”

And then there’s climate change, which further threatens

the kelp forests on which abalone depend. In Southern

California, intensifying El Niño and “warm blob” events

bring unusually high ocean temperatures, and limit the dis-

solved nutrients that Macrocystis, commonly known as giant

kelp, needs for growth. Farther north, when Nereocystis, or bull

kelp, aren’t being chewed down by urchins, they’re likely to be

torn away by increasingly harsh winter storms.

“It’s a sad story of serial screwing-up of the ecosystem,”

All seven abalone species in California, including red abalone (pictured) are struggling to hang on. The state has banned wild abalone harvesting
until at least 2021.