Dungeness and Rock crabs are off limits for seafood lovers until further notice, the California Department of Public Health (CDPH) warns. Researchers recently discovered potentially deadly levels of domoic acid – a naturally occurring toxin from algal blooms – in crabs caught along the California coast line. This poses a significant risk to the public if consumed, according to a news release from the CDPH.

Domoic acid is a neurotoxin that can cause nausea, diarrhea or dizziness when exposed to low levels. However, exposure to high levels can cause short-term memory loss, seizures and can even prove fatal.

"Domoic acid accumulation in seafood is a natural occurrence that is related to a 'bloom' of a particular single-celled plant called Pseudo-nitzschia. The conditions that support the growth of this plant are impossible to predict, and it is unknown when the levels found in crab will subside. The health advisory will be lifted once the levels are no longer above acceptable levels," the CDPH wrote in the release.

Marine animals, such as crabs, filter their food through seawater. In doing so, they accumulate and are susceptible to high levels of domoic acid. While such accumulation does not appear to harm the crabs, it does make the crustaceans poisonous to humans who eat them, regardless of how much they are cleaned or cooked.

In order to monitor toxic levels, the CDPH along with other state agencies will continue to collect and sample Dungeness and Rock crabs in this area. Levels of domoic acid in tested crabs ranged as high as 190 parts per million, Pat Kennelly, CDPH food safety section chief, told the Los Angeles Times. Current regulations state that domoic acid levels cannot exceed 30 ppm in the crabs' internal organs (viscera) or 20 ppm in the meat.   

When exposed to domoic acid poisoning, symptoms may appear in as little as 30 minutes after eating toxic seafood.

"So far there have been no reported illnesses associated with this event," the CDPH added in the release.

This toxic boom occurred just days before the opening of recreational Dungeness crab season, which has since been delayed by the California Fish and Game Commission.

The commercial Dungeness crab fishery accounts for roughly $60 million a year and is vital to small fishermen on California's coast, according to the Los Angeles Times. Prime time for catching Dungeness crabs occurs throughout November and December, when they are most often consumed during holiday celebrations.  

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