, Salem, MA

March 7, 2014

Battle plans laid for green crab

Tarr, stakeholders see growing threat to shellfish

By James Niedzinski
Staff Writer

---- — The invasive green crab — and how to stop its devastation of the state’s shellfish industry — is drawing new calls to arms among the industry’s stakeholders and others.

And while a Monday night forum organized by state Sen. Bruce Tarr, R-Gloucester, state Rep. Brad Hill, R-Ipswich, Rowley Shellfish Constable John “Jack” Grundstrom and the state Division of Marine Fisheries at the DMF’s Gloucester office on Emerson Avenue didn’t bring firm solutions, stakeholders seemed to achieve one consensus.

“The one thing we all agree on is that they are a threat that have to be confronted,” Tarr said Wednesday.

According to a report by Alyssa Novack of the University of New Hampshire and Peter Phippen of the Massachusetts Bays Program, the invasive species arrived in New England in the 1800s in the ballast waters of ships.

“The green crab’s ability to tolerate a wide range of environmental conditions makes it a consummate invader and a threat to ecosystems as it can displace natives through competition and predation,” the report reads. “A recent explosion of the Green Crab population in Nova Scotia and Maine due to warmer waters has led to the rapid decline of soft-shell clams and eelgrass populations and there is now growing concern that this invasive species poses a significant threat to the coastal economy of Massachusetts.”

Many acknowledge that the green crab’s numbers have ebbed and flowed throughout the years and warmer winters mean more crabs — some have suggested that the cold kills them outright.

But Gloucester Shellfish Constable Dave Sargent added that colder winters could mean green crabs suffer less from predation as well.

When clams spawn naturally every year, he said, they lie just beneath the surface of the sand, making them easy targets for the crabs.

“They can just mow though them as if they were Rice Krispies,” Sargent said. “It impacts the lack of sustainable recruitment.”

Alan Young, a professor at Salem State University, suggested that frigid temperatures “may very well suppress the reproductive season.”

According to the DMF report, green crabs can lay up to 185,000 eggs at a time, and can have multiple clutches of eggs a year. The invasive species can reach maturity anywhere from one to three years and can live up to seven years.

They prey on shellfish, other green crabs and many other species. And while the crabs do have some natural predators; there is less than a 50 percent mortality rate on crabs that measure 5 millimeters and a 10 percent mortality rate on crabs that measure crabs up to 25 millimeters.

They are also known to shred eelgrass, according to Steve Woodman, co-owner of Woodman’s Restaurant in Essex — billed as birthplace of the fried clam.

“It’s a problem of more than just clams,” Woodman said. “It’s the whole ecology of what’s in the tidal zones.”

While he said there are other factors in the decline of clamming, the green crab could have been a culprit all along.

“Looking at a lot of the history, it seems like green crabs could have been a major influence in clamming,” he said.

Woodman and others said the problem is much worse in Maine; some have predicted that the clam industry in The Pine Tree State could be gone in two years.

And impacts in Maine markets as well as local ones will have a direct impact on restaurants and customers as Woodman and other restaurateurs have different clam sources.

Grundstrom, a third-generation clammer, echoed what others have said: the crustacean may well be the root of all evils in their ecosystem. He said that, when the crabs consume one food source in a particular area, they simply move onto the next — they are not picky eaters.

That disrupts the entire food chain, from herring to cod all the way up to tuna, he said.

As far as solutions go, some suggestions included exploring the uses for the green crab as bait for tautog, lobster, or the Canadian Whelk as well as potential uses as animal feed or human consumption. As the DMF notes, hundreds of tons of the invasive crabs are used for fish paste in Portugal, but they are difficult to process and it leads to an accumulation of biotoxin.

“Solutions, I don’t think, were hard and fast,” Sargent said.

He added any choice or effort made to get rid of green crabs will have outcomes elsewhere, but he was open to a number of ideas.

“Too often I think we look to single answers to complex problems,” he said.

Woodman, for his part, even funded the visit of a Canadian businessman, Ron Howse, who has said there are markets for the invasive species in Asia. He said that, around 10 years ago, there was a small market for the crabs here to use as bait, but many forgot about those uses.

“The consensus of the meeting was that we need a plan and we can’t reduce any time in reducing the (crab) population,” Tarr said.

Tarr said others need to be aware of potential uses for green crab, and Grundstorm agreed; he even had a list of recipes handy.

One suggestion, Tarr said, was to employ a limited number of people in the summer to trap and catch the crabs. And, considering the imminent threat to the industry and ecosystem, a program costing between $10,000 to $30,000 could be a worthwhile investment, he said.

“I want to make sure before the government gets involved that there could be a market without the government,” he added.

Phippen and Novack, meanwhile, are seeking funds through the Massachusetts Bays program to monitor the green crab population in the Great Marsh across Cape Ann and the North Shore.

“Recent data indicates that the green crab population is a threat to this system’s natural resources because it is hyper-abundant, with a catch per unit effort greater than 40 crabs per trap in a 24 hour period,” their report states.

They plan to monitor 12 stations in Essex Bay and another 12 in Plum Island Sound four times a year to better understand the structure of the crab population, which will lead to a well thought out management plan.

Grundstrom was supportive of the Gloucester meeting and the discussion, but said he’s also eager to see the downfall of the green crab’s growing Northeast empire.

“We have studied this thing to absolute death,” he said. “What we need to do now is get it done.”

James Niedzinski can be reached at 978-675-2708 or at