Scientist: Odd-looking Maine lobsters are not mutants, and still safe to eat

Posted March 10, 2014, at 3:08 p.m.
Last modified March 10, 2014, at 8:43 p.m.

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Lola, a six-clawed lobster living at the Maine State Aquarium in Boothbay Harbor last year, is unique in that she has five claws on her left appendage alone.
Maine State Aquarium
Lola, a six-clawed lobster living at the Maine State Aquarium in Boothbay Harbor last year, is unique in that she has five claws on her left appendage alone.
This lobster, almost exactly half-red, was caught by an Owls Head lobsterman and donated to the Gulf of Maine Research Institute in Portland by Ship to Shore Lobster Co.
Contributed image
This lobster, almost exactly half-red, was caught by an Owls Head lobsterman and donated to the Gulf of Maine Research Institute in Portland by Ship to Shore Lobster Co.
A lobster that was found last year off the coast of Maine near Oak Point in Trenton apparently has lobster shell disease, which has resulted in a noticeable rough shell.
Rose Dennis
A lobster that was found last year off the coast of Maine near Oak Point in Trenton apparently has lobster shell disease, which has resulted in a noticeable rough shell.

ELLSWORTH, Maine — There are some funny-looking lobsters in the Gulf of Maine but all are safe to eat, according to a lobster scientist at the University of Maine.

Lobsters with unusual colors, extra sets of claws or pockmarked shells occasionally turn up in lobstermen’s traps or are discussed at fishery forums. If it’s not the flavor that’s on their tongues, it’s these unusual appearances that often are the topic of conversation.

Lobsters that sprout malformed claws that display multiple sets of pincers — like a pocketknife with all the blades and tools pulled out — are not “mutants,” according to Bob Bayer, executive director of UMaine’s Lobster Institute and a professor of animal veterinary sciences at the university. Bayer said Monday that the malformations are not genetic but occur when a lobster molts and somehow signals get crossed as a new, larger shell hardens.

Lobsters have the ability to regrow limbs, Bayer said. Often, they lose a claw during fights with other lobsters or marine creatures.

“They drop claws routinely as a way of getting away,” Bayer said. “Those claw malformations happen on a regular basis.”

Sometimes, when a lobster suffers some sort of injury to a claw and then sheds its old shell in favor of a bigger one, a claw will get a mixed message — that a new limb needs to grow instead of simply a new shell just hardening. As a result, a second set of pincers may sprout from a healing injury off the side of an existing claw.

Assuming the lobster can continue shedding its deformed claw shell on successive molts, the malformation will continue to grow as the lobster gets bigger, according to Bayer. But if the claw gets “dropped” in another confrontation, he said, the extra set of pincers likely would vanish with it.

“It would probably be normal,” Bayer said of the regenerated claw.

Lobsters with extra sets of claws are not the only unusual-looking lobsters in the Gulf of Maine.

Live lobsters typically are dark brown, with lighter shading on claws and tails. But occasionally fishermen or researchers find lobsters that are bright red or orange (the color they turn when cooked), blue, have mottled shell patterns or are two different colors on each side — brown on the left side and orange on the right, for example.

These genetic color variations are rare but harmless, according to Bayer. They have no effect on the health or edibility of the lobster.

“You see them in the summertime, when they’re being caught,” the UMaine professor said.

Some lobsters with pockmarked shells do have health problems — though they also are harmless to consume, according to scientists. Lobster shell disease, a condition that has been more prevalent south of Cape Cod, appears to be increasing in the Gulf of Maine though its occurrence rate still seems fairly low.

The condition appears to be caused by naturally occurring bacteria that consume the shells of living lobsters, making the lobsters unsightly and possibly weak. Though the lobster meat is unaffected in appearance and flavor, the disease can depress the value of Maine’s $364 million lobster fishery catch because the scars and lesions on affected animals make them unsuitable for the lucrative restaurant market.

By Bayer’s estimate, between 1 percent and 2 percent of lobsters in the Gulf are affected by shell disease. Scientists continue to debate whether increasing ocean temperatures, relative acidity, food availability and population density might be contributing factors, while some believe something internal in the lobster — its genetic makeup, a pre-existing condition or another type of stress — could trigger the disease.

 

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