Scientists say an explosion of invasive green crabs that threatens Maine's lucrative soft-shell clam industry appears to have tapered off, at least temporarily.
The crabs took over hundreds of acres of Maine mudflats last year, pressing regulators and fishermen into action to slow the crustacean's rapid growth.
This year, the amount of crabs is 10 percent of last year's level at a key Freeport trapping site, University of Maine at Machias marine ecology researcher Brian Beal said. And anecdotes from around Maine's coast suggest the same trend is happening elsewhere.
The harsh winter might have culled the population, Beal said. He added trappers are finding mostly smaller green crabs, suggesting the larger crabs often found last year may have died or gone out to deeper water.
The lower abundance follows a year of aggressive crab trapping and habitat fencing in coastal Maine. Marine biologist Darcie Couture, who is studying the crabs in Harpswell and Brunswick, said she has also seen fewer. She said she fished about 400 pounds of crabs out of Brunswick coves this summer - a number she could've reached in a single day in 2013.
"The numbers are way down," Couture said. "We're not sure if we made the dent, or if it was the severe winter."
The crabs, native to Europe, first became noticeable in Maine around the turn of the 20th century. They threaten the soft-shell clam fishery, which is the third largest in Maine and generated almost $17 million in 2013, and damage coastal habitats like eelgrass beds and salt marshes. State officials say the crabs have increased population as the temperatures of the ocean off of Maine have risen.
The lower abundance coincides with a state effort to prompt crab harvesting. Maine changed rules last month to allow commercial fishermen to harvest and sell green crabs without a special license, and they also no longer need to report green crab harvests to the state. Fishermen are searching for a way to make the crabs commercially viable, possibly as pet food, fertilizer or bait, but the selling price remains too low to justify much commercial fishing.
Although the annual haul increased from 3,762 pounds in 2012 to 10,596 pounds in 2013, there is a limited market for them, state Department of Marine Resources spokesman Jeff Nichols said.
"There has not been a viable, steady market identified," Nichols said.
The crabs remain abundant in some parts of the coast, said Kristin Wilson, director of research at Wells National Estuarine Research Reserve, who cautioned against considering the problem abated. Trap studies show low numbers in Yarmouth, but Wells and Damariscotta remain high, she said.
"It may be that the impacts were variable along the coast," she said.