RETENTION OF DOMOIC ACID BY PACIFIC RAZOR CLAMS, SILIQUA-PATULA (DIXON, 1789) - PRELIMINARY-STUDY

Domoic acid concentrations up to 160 mug g-1 shellfish meat were repor ted in razor clams on the Washington/Oregon coasts in the fall of 1991 . Toxin levels in the clams remained above the regulatory closure leve l of 20 mug g-1 for at least 6 months. In summer, 1992, razor clams, a veraging about 10 mug g-1 of domoic acid toxin, were maintained under laboratory conditions to determine bow long it would take them to be f ree of the toxin. Periodically, edible (foot, siphon, and mantle) and non-edible (gill, digestive gland, and gonad) parts were tested for do moic acid. After 86 days, toxin levels remained near the original leve ls, but at least one clam in each group of six tested contained ca 22 mug g-1 reflecting the clam-to-clam variability in their natural habit at. It appears that razor clams are able to depurate domoic acid in th eir natural environment, but may maintain a low level of domoic acid f or long periods.