Half Moon Bay and Monterey crab test under 10 ppm domoic acid; Bodega Bay north is untested.

The highest single reading in the newest California crab tests is 9.8 parts per million of domoic acid, from a Dungeness crab caught off Monterey Bay on September 28. The limit is 30. That is from the state's summary of domoic acid levels in crab, current to October 16. It also shows what is missing: the table has four sets of crab, all from Monterey Bay and the Half Moon Bay area, and none from Bodega Bay, San Francisco or anywhere north.

Domoic acid is a nerve toxin made by a diatom called Pseudo-nitzschia. Crabs eat what feeds on it and store the toxin in their guts. The federal action level, set in a 1993 memorandum that the FDA's hazards guide still cites, is more than 30 mg/kg in Dungeness crab viscera; mg/kg is the same as parts per million. For the meat the level is 20, and CDPH says cooking removes none of it. Eating enough causes vomiting and, in severe cases, seizures and permanent loss of short-term memory.

Where the toxin goes, a closure follows

The chain of decisions is written down. The state's Office of Environmental Health Hazard Assessment, with CDPH, recommends a delayed opening when domoic acid meets or exceeds the action level, and CDFW carries it out. According to CDFW's health-advisory page, reopening is recommended when levels fall below the limit in two successive samples taken at least seven days apart. CDPH's tables count a site as passing only after two consecutive clean sets of six crabs.

Last season shows how slowly that can run. On September 24, 2025, six crabs from Trinidad Head, Humboldt County, read 180, 79, 13, 49, 19 and 10 ppm, three of them over the limit, in the 2025-26 test record. Retests there ran through four rounds, to a second set on January 18, 2026. CDFW's crab page records the statewide opening as January 30.

A toxin reading does not always close a season. Since a 2021 law, CDPH can permit processors to eviscerate crab, removing the guts, when the viscera is at or above 30 ppm but the meat is below 20, and the crab then goes only to a CDPH-approved California processor. Evisceration only applies when the meat passes.

The cause is hard to forecast. CDPH writes that the conditions that support Pseudo-nitzschia growth are difficult to predict. A clean October says the crab were clean in October.

The Bay Area's delay last year came from whales, not toxin

The same record separates the two causes. Half Moon Bay area crab read under 2.5 ppm in every sample on October 8 and October 15, 2025, and the Bodega Bay sites on October 18 peaked at 26 ppm, at the Russian River, still under the limit. Yet on October 24, 2025 the Director delayed the commercial season in all zones, citing entanglement risk, per the Whale Safe Fisheries record. On December 19 the Director opened Zones 3 to 5 on January 5 under a 40% gear reduction. Zone 3 runs from the Sonoma/Mendocino line to Pigeon Point and holds Bodega Bay, San Francisco and Half Moon Bay. Zones 1 and 2, the north, were held to at least January 15 pending testing.

So for the ports that land crab near Sacramento's markets, the toxin has been the lesser of the two gates. We did not find a published figure for how much of the crab sold in Sacramento lands there, so we do not give one. We also did not find a source that ties Delta outflow to toxin in the Gulf of the Farallones, and make no claim about it.

What this fall's record does and does not say

Three things are in the record. First, CDFW's page lists both the commercial and recreational 2026-27 fisheries as closed, with no 2026-27 risk assessment posted yet. Second, CDPH does not routinely test crab while the fishery is closed, so the four sets are the pre-season sample, not a survey. Third, the toxin was in the water this summer. CDPH's seafood table lists northern anchovy viscera at 1,200 ppm on August 28 and 47 ppm on October 6, against a 20 ppm level for that species, and CDFW closed the Monterey Bay anchovy harvest on September 11 and, on October 9, the Del Norte County razor clam fishery.

Crab testing for the quality gate has barely started. The Tri-State preseason sheet shows one result: Westport, Washington, with 19.2% meat recovery on October 21 against 23% required. Every California test area reads "NT", not tested. The sheet lists Bodega Bay and San Francisco under District 10, which it marks as not bound by the Tri-State protocol, so those ports do not wait on the northern result.

What would settle it

Our view is that Zone 3 is more likely to be held by whales than by toxin this year, because the readings so far are low and the only high-toxin signals are in anchovies, clams and, last year, the far north. That view would change with a single set north of Point Reyes over 30 ppm, or with a Director's risk assessment naming entanglement as clear. We could not find the date of CDFW's first 2026-27 call. Last season's first assessment was dated October 24, with data posted October 21 and 22. Anyone holding crab or planning to eat the viscera can check the table above or call CDPH's Shellfish Biotoxin Information Line at 1 (800) 553-4133.