Black Abalone “Recruiting”

Black abalone at a cove on San Nicolas Island in 1985. Credit: Glenn VanBlaricom

Black abalone at a cove on San Nicolas Island in 1985. Credit: Glenn VanBlaricom

Scientists are seeing high numbers of young, thumb-size black abalone “recruits” on San Nicolas Island in the Channel Islands.

The recovery is occurring at only one site on the remote island, but the success offers a glimmer of hope that some degree of recovery for the federally protected endangered species may be possible.

No recruitment is being seen anywhere along the California mainland, which is part of the once plentiful animal’s historic range.

“It’s wonderful that we are observing recruitment at this one site because it hints at a recovery strategy,” said California Sea Grant marine ecologist Pete Raimondi of UC Santa Cruz.

Abalone are large intertidal marine snails that begin life as free swimming larvae and then “settle” onto rocks and metamorphose into tiny versions of their adult self. Scientists are able to spy and count the animals when they are about 1-inch long and about 1-2 years of age.

Last year, biologists counted 1,430 animals at nine survey plots on the island and are currently estimating a 5 percent reduction in these numbers for 2013.

“The numbers are encouraging, but we have a long way to go,” said Sea Grant biologist Glen VanBlaricom of University of Washington in Seattle. VanBlaricom was recently elected chair of the Endangered Species Act Black Abalone Recovery Team, convened by NOAA Fisheries.

“From 1981 to 1992, we were counting 24,000 animals annually on average during our surveys,” he said. A lethal bacterial disease known as withering syndrome decimated populations to a low of 195 animals in 2001.

Sea Grant scientists led by shellfish pathologist Carolyn Friedman of University of Washington in Seattle recently confirmed that one resident population of black abalone on the island’s south side is resistant to the disease.

Scientists are now talking about breeding disease-resistant abalone to help rebuild wild populations and based on what they are observing in the field, believe that any recovery plan should include aggregating abalone into deep, narrow rocky cracks and crevices.  The scientists believe that higher numbers of adults in these preferred habitats are what is needed to ensure successful reproduction and maintain quality habitat for “baby” abalone.

Written by Christina Johnson,

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