Crabbing in West Marin and along the state’s coast is officially shut down as of Thursday, after the California Fish and Game Commission voted during an emergency meeting to prohibit recreational take and possession of Dungeness and rock crabs from all ocean waters north of Santa Barbara. An unusually long swath of algal blooms has spurred such high levels of a neurotoxin—called domoic acid—in crabs that consuming them presents serious health risks to humans and marine mammals.
The season was scheduled to open on Nov. 7 for recreational Dungeness crab catches and Nov. 15 for commercial. Now, those start dates have been delayed indefinitely until the director of the state’s Office of Environmental Health Hazard Assessment deems that domoic-acid levels in crabs have fallen to a level that no longer poses a threat to human consumption.
Rock crab fisheries, which are open yearlong, have also been closed.
A list of all currently closed ocean waters may be found at https://www.wildlife.ca.gov/fishing/ocean/health-advisories.
A decision to delay the season was prompted by warnings issued earlier in the week from the Department of Public Health that implored consumers to avoid eating Dungeness and rock crabs caught in coastal waters from Oregon down to Santa Barbara. Testing conducted by the health department at nine different sites since September revealed that accumulated levels of domoic acid in the crabs far exceeds the federal standard of 20 parts per million. Amounts of the toxin found in one yellow rock crab sample from Monterey reached a staggering 190 p.p.m.
Though a definite reopening date remains unknown, state agencies recommended on Tuesday that the ban be lifted only after weeks-long lab tests across the state show that domoic acid levels have fallen back down to federal standards.
Prevalent in algal blooms (commonly known as red tides), domoic acid occurs naturally in phytoplankton and, if consumed by mammals in large quantities, attacks the brain’s hippocampus to cause severe memory loss as well as seizures potentially resulting in death. First diagnosed by the Marine Mammal Center in 1998, domoic-acid poisoning has struck more than 210 sea lions so far this year, with nearly all of them succumbing to the toxin.
“It’s a very potent neurotoxin,” said Dr. Claire Simeone, a veterinarian with the center. “And even at low doses, it can cause vomiting and dizziness in humans.”
The huge algal bloom wherein domoic acid thrives is the most extensive bloom that the National Oceanic and Atmospheric Administration has ever recorded, Dr. Simeone said, stretching from Alaska down past Central California. She attributed much of the bloom’s explosion to warm water down the coast, an indication that the current El Niño episode may already be taking its toll on marine ecosystems.
“All of the ecosystem is affected” by the bloom, Dr. Simeone said. “And the El Niño they’re predicting for this winter is certainly not going to help.”
In Bolinas, crab sales typically net local fisherman Don Murch about a third of the income he makes at Gospel Flat Farm, which he and his family have run for over 30 years.
Mr. Murch’s farm sets 250 crab traps in the Gulf of the Farallones and, on a good opening day, will catch between 40 and 50 crabs in each trap.
Without the crabs, Mr. Murch said he plans to simply grow more vegetables. Given that the brunt of his catch goes straight to the town’s Thanksgiving tables, he predicted that the season’s delay would mostly hurt the public’s enjoyment of a tasty holiday pastime.
“It’s usually pandemonium around Thanksgiving,” Mr. Murch said. “If we don’t catch it in November, we’ll catch it in December.”
But, he wondered, does the domoic acid spike signal more permanent environmental alterations than just a single-season inconvenience this year?
“Maybe it’s part of our new cycle,” he said. “Maybe it’s long-time changes in the ocean caused by who knows what. Hard to say.”
This story was modified on Thursday, Nov. 5 to reflect up-to-date information on the state of the Dungeness and rock crab fisheries. The print version of this story reflects the information available on Nov. 4.