The Maine Department of Marine Resources has closed the islands from Isle au Haut to Frenchboro to shellfish collection due to the presence of red tide.

Collection of mussels, European oysters and carnivorous snails are prohibited around Isle au Haut, Swans Island and Little Duck Island until further notice. This is typically one of the first areas in eastern Maine to be affected by red tide, according to DMR.

Darcie Couture, who directs the department’s Biotoxin Monitoring Program, wrote in an e-mail that staff will work with harvesters on Swans Island to allow clam harvesting on the island for as long as possible.

The area from Pemaquid Point south to the New Hampshire border also remains closed to most shellfish collection because of red tide.

Red tide is caused by blooms of toxin-producing algae. Clams, oysters, mussels and carnivorous snails can all absorb the toxins as they feed on the algae. Eating shellfish affected by the toxin can cause sickness or death.

Lobster, crabs and scallops are not affected by red tide.

Marine biologists have predicted that 2008 could be a bad year for red tide in Maine. Monitoring programs ensure that shellfish that make it to commercial market are safe to eat, however.