The surprising invasion of phytoplankton affects hundreds of acres of clam flats in Freeport and Brunswick and at least 12 mussel and oyster farms.
A rare late-season toxic algae bloom has closed most of the fertile shellfishing areas in Casco Bay, disrupting the region’s wild-caught and farmed shellfish industry.
The state Department of Marine Resources expanded the area of the harvesting ban Tuesday so that it now stretches from Portland Harbor to the west side of Harpswell. The closure was triggered when tests of shellfish flesh showed elevated levels of domoic acid, a naturally occurring toxin that can produce sickness and brain damage in humans.
The ban affects hundreds of acres of productive clam flats in Freeport and Brunswick and at least a dozen mussel and oyster farms in those towns and around Chebeague Island. There were about 179 licensed clammers in Casco Bay in 2016, but 45 were in Harpswell, which has not been as heavily affected by the closures. The number of full-time clammers is much lower than the total number of licensees. Almost all people who are clamming at this time of year are full time, not recreational or seasonal, fishermen.
The domoic acid is being produced by a large phytoplankton bloom that includes species of Pseudo-nitzschia, the same kind of single-cell organism that closed large sections of the Down East coast to harvesting and forced shellfish recalls in the past two years.
This is the first recorded bloom of toxic Pseudo-nitzschia in Casco Bay….more here