Parts of the coast had been closed to mussel and clam harvesting due

to red tide.

PORTLAND (AP) – State officials on Thursday reopened a large chunk of the Maine coast to mussel and clam harvesting as the worst case of red tide in more than two decades slowly dissipates.

A severe bloom of toxic red tide in the past several weeks has forced clam diggers and mussel farmers to take time off. Although large areas of the coast are still closed, toxin levels have dropped in other areas to allow shellfish harvesting to resume.

On Thursday, state officials reopened the area from Biddeford Pool to Flying Point in Freeport.

Tollef Olsen kept smiling as he unloaded several crates of fresh mussels at Harbor Fish Market in Portland on Thursday. “We’re back,” he said. “It feels good.”

Olsen owns Aqua Farms, LLC, a small-scale mussel farm in Casco Bay, and was down for about three weeks.

Red tide is the common name for a type of algae that can bloom in large numbers under the right conditions. The algae was so thick in some areas this month that people reported seeing a reddish tint in the ocean, a characteristic that gave the algal bloom its notorious name.

When the level of toxin approaches 80 micrograms per 100 grams of meat from mussels, the state recommends a closure. The red tide this fall showed dangerously high toxin levels of around 3,000 micrograms.

Besides being unusually severe, the recent red tide occurred later in the season than usual.

Scientists believe the algae bloomed later because it was a foggy, overcast summer followed by a sunny September. Storms and hurricanes may have pushed the red tide from offshore to the coast.

While parts of the coast are now open to shellfish harvesting, seven zones remain closed where it is prohibited to harvest carnivorous snails, soft-shell clams, oysters, surf clams, whelks and quahogs. Red tide does not affect lobsters, shrimp, crabs, finfish or periwinkles.

Fish markets have adjusted to the closures by getting enough mussels and clams from out of state to meet demand, said Mike Alfiero, an owner of Harbor Fish Market in Portland.

“If it was around on the fourth of July, it would have been a disaster,” he said.

AP-ES-10-24-03 0216EDT