A shellfish harvesting ban has been expanded in Down East Maine following a harmful algae bloom that prompted a recall of some mussels last week. State officials are still trying to determine how much product was affected by the recall.

The Department of Marine Resources on Friday closed a section of the Penobscot River north of Stockton Springs and of Cobscook Bay south of Eastport to the harvesting of mussels, clams and oysters. It also expanded a precautionary harvesting ban as far north as Calais in Washington County.

Harvesting was suspended in Frenchman Bay east of Mount Desert Island on Thursday after mussels in the area tested at elevated levels of domoic acid, a neurotoxin produced by a “widespread and abundant” bloom of Pseudo-nitzschia, a marine phytoplankton. At the time, officials issued a precautionary ban from Gouldsboro to Machiasport and around Isle au Haut, Swans Island and Vinalhaven.

Department officials expanded the closures as a precaution after detecting an increasing concentration of phytoplankton in the water, said spokesman Jeff Nichols. Shellfish tested from the newly closed areas are under acceptable limits for the domoic acid – 20 parts per million – set by the U.S. Food and Drug Administration, Nichols said.

Meanwhile, department officials are still quantifying the amount of mussels that were recalled Friday from five dealers. The recall only affected mussels harvested in Frenchman Bay between Mount Desert Island and Gouldsboro between Sept. 10 and 14. In an email Monday, Nichols said he did not have an update on how much product was recalled. Several seafood dealers on Friday said they believed most of their product was recalled before it reached consumers.

Pseudo-nitzschia is native to Maine waters, but this only the second toxic bloom of the phytoplankton on record. Domoic acid is stored in the flesh of bivalve shellfish that feed on the algae. It can cause illness, brain damage and death in humans if ingested.

Harvesting areas will reopen after two consecutive shellfish tests at least one week apart show toxin scores below the federal action limit, Nichols said.

Peter McGuire can be contacted at 791-6325 or at:

[email protected]

Twitter: @PeteL_McGuire