Green crabs, the scourge of Maine clam flats for the past several years, may have more to worry about from Mother Nature than from lobster fishermen.

According to fishery officials, the cold winter may prove to be more effective at keeping them in check than trying to get lobstermen to use them as bait.

There has been heightened interest in recent years for finding a commercial application for green crabs, an invasive species that has decimated clam flats along much of the coast. With $19.2 million in commercial landings last year, soft-shell clams represent the second-most valuable fishery in Maine, behind lobster.

Using the crabs as bait in the lobster fishery — which generated nearly $457 million in statewide revenue for fishermen in 2014 — has been considered as a possibility. The supply of traditional types of bait, such as herring and pogies, has been declin- ing, and lobstermen have been looking for readily available and affordable alternatives. Some have even turned to using cowhide, which, according to people who use it, lasts longer in and out of the water than marine baits. Baiting lobster with green crabs might not be such a good idea, however, according to a study by a pair of Canadian scientists that was presented last month at a fisheries science conference in Dartmouth, Nova Scotia.

The study indicates that a parasite called profilicollis botulus has been found in lobsters baited with green crabs, according to an article recently published by the Chronicle Herald newspaper of Halifax, Nova Scotia. The scientists did not find any trace of the parasite in lobsters trapped with other types of bait.

Not a threat to humans

The parasite does not pose a threat to humans, nor does it affect the taste of lobster meat, according to the Chronicle Herald report, but it does make lobster more susceptible to predation and results in higher mortality rates among lobsters held in pounds. The record value of Maine’s lobster fishery in 2014 has been attributed in part to the relatively robust health of lobsters in the Gulf of Maine, which are shipped live to seafood markets around the world.

Bob Bayer of the Lobster Institute at University of Maine said recently that, because of the Canadian study, his organization recommends that lobstermen do not use green crabs as bait, at least until further studies can be conducted.

“These are credible people,” Bayer said of the university research scientists who conducted the study. “Don’t do it.”

Green crabs have been found in waters off New England and Atlantic Canada since the 1800s, when they hitched rides across the ocean on ships sailing from Europe.

Concern about the impact the crabs have had on this side of the Atlantic has soared in recent years as a series of mild winters have caused a population explosion along the coast. The voracious crustaceans have cleaned out clam flats and devoured eelgrass beds, leading industry and state officials to explore ways to develop markets for green crab products and to explore other ways for keeping their population in check.

According to Bayer, the cold weather this winter may do more to reduce the green crab population than anything else. Between the heavy snowfall and the unusually cold temperatures, he said, the numbers of green crabs along the coast are expected to be lower this year.

“(The winter) could kill off a lot of them,” Bayer said. “I would guess it would (cause) a big dropoff.”

Despite the concerns about green crab, the species is not on lists of types of aquatic bait that have been banned by the state for use in Maine’s lobster and crab fisheries.

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