Maritime researchers are on the lookout for a bacterial infection that eats away at lobster shells and has plagued the southern New England lobster industry for years.

The infection is moving north and currently affects about one in every three or four lobsters caught off of southern Massachusetts, officials say.

Lobsters with infected shells are turning up as far north as Maine, but a recent sampling shows no sign of the disease in the Maritimes, said Michel Comeau, a lobster biologist with federal Fisheries and Oceans Canada in Moncton.

"But we want to keep monitoring it for the future," he said.

Shell disease does not taint the meat of the lobster and is not harmful to humans, but does make infected lobsters difficult to sell because they are unsightly.

Cause unknown

It can, however, interfere in the molting process, preventing the lobster from releasing its shell and causing it to die.

"Everybody's on the watch for it, to see if there's any kind of spread into their area," said Robert Macmillan, a provincial lobster biologist in Prince Edward Island.

"I don't know how or when or if it will ever reach this part of the world."

Comeau agrees. Limited knowledge of the disease makes it difficult to predict whether it will ever become a problem in the Maritimes, he said.

"The United States spent millions of dollars trying to identify the cause, however the real cause of why it is affecting some lobster in some areas and not really in other areas, nobody knows really."

The infection first appeared in New England waters in the 1990s.

It's unknown whether the origin of the disease is related to warmer water temperatures, said Comeau.