Commercial Crab Biotoxin Information

If Demoic Acid levels rise above the Federal Action level of 30 ppm the viscera (guts) or 20 ppm in the meat, closures are issued. See below to view information on the current closure areas on the ODA (Oregon Department of Agriculture) website.¹

Click Here to View Closures

All U.S. coastal states test commercially and recreationally fished animals for biotoxins, following the same federal standards and methods. When biotoxins are found to be at or above the action level – the safety threshold set by the U.S. Food and Drug Administration – the state issues an advisory and may close the fishery to protect consumers from potential health hazards. Often, only certain states or areas within a state may require advisories/closures. ³

Demoic Acid what is it?

Demoic Acid is a naturally occurring toxin produced by marine algae. It occurs in the viscera (guts) or meat of crab that has eaten affected clams. Eating shellfish contaminated with Demoic Acid can cause minor illness within minutes or hours. Demoic Acid is not destroyed by cooking, by adding baking soda, or by any other method of processing, and there is no known antidote. Demoic Acid causes a condition called amnesic shellfish poisoning (ASP). In mild cases, symptoms can include vomiting, diarrhea, abdominal cramps, and headache which develop within 24 hours of ingestion. More severe cases can result in memory problems and death. ²

How likely am I to be exposed to this toxin by eating crab?

Domoic acid  not usually present, so typically crab can be enjoyed without concern. However, even when the toxin is present, the levels can vary tremendously among crabs from the same or different areas. Further, the way you prepare the crab, which parts you consume, and the amount you consume all can influence exposure to the toxin.³

The toxin is highly concentrated in the internal organs (viscera, guts, crab butter) of crab. If people avoid eating and cooking with these parts of the crab, their risk of exposure to the toxin will be greatly reduced.³

Demoic acid is not destroyed by heat, but it is water-soluble. This means boiling crab in water (liquid) can cause Demoic Acid to leach out into the water. This is why we recommend you discard said liquid; and do not use it to prepare sauces, soups or other food items.³

Author -Amanda Wolf  © January 22nd, 2018
¹ “Recreational Shellfish Biotoxin Closures.” Oregon Department of Agriculture: Recreational Shellfish Biotoxin Closures, Oregon Department of Agriculture, http://www.oregon.gov/oda/programs/foodsafety/shellfish/pages/shellfishclosures.aspx.
² Culver, Carolynn, et al. “Natural Biotoxins in California Crabs: Domoic Acid.” California Sea Grant, caseagrant.ucsd.edu/sites/default/files/Biotoxins-SU16-FAQ-v2.pdf.
³ “DOMOIC ACID – A Major Concern to Washington State’s Shellfish Lovers.” Washington Department of Fish & Wildlife, 2018, wdfw.wa.gov/fishing/shellfish/razorclams/domoic_acid.html.