The California Department of Public Health is warning consumers not to eat rock crabs caught in Half Moon Bay and bivalve shellfish and rock crabs caught in Monterey Bay. A high level of domoic acid, a naturally occurring toxin, has been found in those fish.
The warning is for crabs and bivalves caught in state waters south of Latitude 37° 11′ N. (near Pigeon Point) and north of Latitude 36° 35′ N (near Cypress Point in Monterey County). The advisory includes recreationally and commercially harvested rock crab, and recreationally caught mussels, clams, and the internal organs of scallops caught in the warning area.
Domoic acid is a neurotoxin that causes amnesic shellfish poisoning (ASP). The neurotoxin accumulation is related to the bloom of a single celled plant. The conditions that support the growth of this plant are impossible to predict. The symptoms of domoic acid poisoning occur quickly, usually within 30 minutes to 24 hours after eating contaminated seafood.
Symptoms of this illness include vomiting, diarrhea, abdominal cramps, headache, and dizziness that go away after several days. But in severe cases, patients may have trouble breathing, confusion, disorientation, cardiovascular instability, seizures, permanent loss of short term memory (ASP), coma, or death. No illnesses have been reported in association with this problem.
Public officials have analyzed rock crabs recently caught in Half Moon Bay, and found domoic acid levels in the viscera (internal organs) to be more than 10 times the action level, set at 30 ppm. Because this spike is so high, officials are concerned about crabs and bivalves taken from this entire geographic region.
This warning doesn’t apply to commercially sold clams, mussels, scallops or oysters harvested from approved sources. Only state-certified commercial shellfish harvesters or dealers can sell these products. The state frequently tests the shellfish sold by certified harvesters and dealers.
If you have eaten rock crabs or bivalve shellfish caught in this area and have experienced these symptoms, see your doctor.