The Department of Marine Fisheries (DMF) has closed all shellfishing in Martha’s Vineyard waters, except for the harvesting of bay scallops. The closure is due to an expanding phytoplankton bloom that shut down shellfishing in all waters south of Cape Cod Tuesday. Rhode Island has also been affected.
“Throughout the weekend, DMF staff collected shellfish samples in closed areas and in areas that remain open, like Cape Cod Bay,” DMF said in a press release. “These samples are being analyzed by an independent laboratory for toxin to determine whether it is necessary to maintain or possibly expand the closures. If shellfish are found to be non-toxic, the waters will be reopened.”
Edgartown shellfish constable Paul Bagnall said it is a “precautionary closure.” He said samples were sent off Monday morning. If no phytoplankton bloom is discovered in Island shellfish the closure could be lifted, possibly as early as Wednesday.
The phytoplankton Pseudo-nitzschia, when concentrated in the gut of shellfish, can cause Amnesic shellfish poisoning (ASP). ASP symptoms include vomiting, nausea, diarrhea, and abdominal cramps within 24 hours of ingestion. In more severe cases, neurological symptoms develop within 48 hours and include headache, dizziness, confusion, disorientation, loss of short-term memory, motor weakness, seizures, profuse respiratory secretions, cardiac arrhythmias, coma, and possible death. Short term memory loss can be permanent.
DMF stressed in a press release that this toxin is not killed by cooking, as is the case with Vibrio, the toxic bacteria that has shut down Island oyster farmers in the past.
Bay scallops are exempt because the toxin is concentrated in the gut and not in the muscle. The muscle in bay scallops is what is usually eaten.
The DMF will be monitoring the concentration of Pseudo-nitzschia in the waters as well as toxicity levels in shellfish meats. The DMF also stated that the level of Pseudo-nitzschia that triggers a closure is lower than the toxicity level that would likely get someone sick.