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Dungeness crab season approaches California, but poison is a familiar threat

Days get shorter, pumpkin spice lattes are here and once again it's time for the other Bay Area rite of…

Days get shorter, pumpkin spice lattes are here and once again it’s time for the other Bay Area rite of fall: worry about the levels of toxins in local Dungeness crabs.

With the State Recreation Dungeness Crab Season scheduled to begin November 3 and the Commercial Season 15 November, the California Public Health Department has released preliminary test results on Dungeness crab for dominoic acid, the neurotoxin that caused delays in two of the last three crab season in the Bay Area.

Up to now, elevated levels of dominoic acid were found in five Dungeness crabs collected from Bodega Bay and Trinidad (Humboldt County) in late September and early October, which is the latest available data. San Francisco, Half Moon Bay, Monterey and Morro Bay regions were clean in this round of tests. The test will continue in the coming days and weeks.

“California Department of Public Health monitors domonic acid levels to ensure a safe food product for consumers,” said Corey Egel of the Office of Public Affairs Department. “At this point it is too early to determine whether reported levels can have an impact on the recreational or commercial Dungeness crab season.”

In Oregon, recreational crabbing on October 1

5 due to domic acid after government officials found high levels during testing. It is still closed from the California border north to Cape Blanco.

Domic acid is a by-product of algal blooms that form when sea temperatures are warmer and can cause disease and even death in marine animals and humans. Although it’s common in summer and early autumn, the flowers usually go out at the time Dungeness crab season starts in November. In recent years, climate change and the El Niño conditions have caused warmer sea temperatures to last for winter and together with dominoic acid. The California Department of Public Health defines elevated levels of dominoic acid as more than the federal action level of 30 parts per million.

“Yes, the tests have shown warm deviations along the northern coast, and we have seen domonic acid spikes up in Humboldt Bay – but not Monterey Bay – so there are definitely some localized hotspots that are developing,” said Raphael Kudela, an algae specialist and Lynn Professor of Ocean Health at UC Santa Cruz via email. “But we do not expect major hot deviations this year.”

However, oceanographs monitor conditions that may cause warmer ocean temperatures to remain in winter, such as the development of a bloody property off the coast of Alaska. The high-pressure hot water concentration is similar to that outside California’s coast from 2013 to 2015, as many believed to be a factor behind California’s drought.

In addition, the National Oceanic and Atmospheric Administration announced only a 70 to 75 percent chance that an El Niño will form this winter. The warmer water temperatures under the El Niño system that began in 2014 led to delays in the Dungeness crab season 2015-2016 and the collapse of the sardine population.

Other parts of the California coast have shown signs of unusually hot conditions in recent months. In August, the warmest ever sea temperatures in San Diego were reported. Last week, biologists reported a growing outbreak of a bacterial infection in California Sea Lion, which is partly due to rising sea surface temperatures.

State Department of Public Health tests domonic acid in Dungeness crab from California ending every two to two weeks. The tests must be clean for two weeks before the crab from that area is determined to eat. In the calendar year 2017, $ 47 million landed in Dungeness crab in California.

Tara Duggan is a staff writer in San Francisco Chronicle. E-mail: [email protected] Twitter: @taraduggan

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