By Jonathan Levitt

“They grow quickly. They have an especially broad habitat, temperature and salinity tolerance that allows for a broad geographic distribution. All of this makes for a great invasive species, and nothing has evolved to handle them.” — Prof. Brian Beal Green crab WASHINGTON DepT. of Fish & Wildlife

Because of their small size (a large green crab would measure  fewer than three inches across), picking green crab meat (just as delicious as rock or Jonah crab) is a tedious and prohibitively expensive process, a fact that has limited any commercial harvest. Without natural predators or a fishery to control their numbers, green crabs will continue to out-compete native species and take a serious toll on shellfish populations.

“Wicked winters and a commercial green crab fishery are the only things that we can hope for,” said Brian Beal, professor of marine biology at the University of Maine Machias.

Since their arrival in the ballast water of trans-Atlantic ships, the invasive green crabs have pushed native species to deeper waters and are now the dominant predator in Maine’s inter-tidal zone.

Native to the British Isles, green crabs were first spotted on American shores in the Long Island Sound around 1800. Since then, the voracious feeders have been feasting their way north along the coast, decimating populations of clams, scallops and lobster.

According to Beal, the green crab is a  “very feisty organism.”

“They grow quickly and reproduce quickly,” he said. “They have an especially broad habitat, temperature and salinity tolerance that allows for a broad geographic distribution. All of this makes for a great invasive species, and nothing has evolved to handle them.”

Working with the Beals Island Regional Shellfish Hatchery, marine biologist Bill Walton received a $10,000 grant from the Maine Technology Institute to study the feasibility of a commercial fishery for the green crab. The hope was to develop a fishery similar to what exists in the Chesapeake Bay with soft-shelled blue crabs. The trick would be to discover a way to catch the crabs during the three-day period when they shed their shell and grow a new, larger shell.

 After eight months, the project petered out. The frequency of the molting was not as high as Walton had predicted and when the money ran out, he was still unable to come up with any marker to make predictions about the time of the molt. 

Beal thinks that figuring out the molting cycles would be “worth another shot.”

“I think it’s a great opportunity and someone should take another crack at it,” he said.

“We could get green crabs the heck out of Maine. They don’t belong here. History has shown that once a species becomes a fishery, it’s destined to doom. It would be great to create markets for green crab.”

Beal sees private investors as the best hope for commercial viability studies on green crabs.

“It will take someone with a business plan,” he said. “With time and sampling and detailed observations, experiments in a controlled setting — manipulating water, food and light we may be able to figure out the molting.”

Denise Skonberg, an associate professor of food scientist at the University of Maine, has been experimenting with products that could create the need for a commercial green crab fishery.

“The only real reason for a green crab fishery is to get rid of this terribly invasive species,” Skonberg said. “We have to find a way to make the crabs marketable. They destroy oyster beds and mussell beds. Lobstermen get them in their traps and those guys just crush them, they hate them so much.”

Skonberg has been experimenting with what she calls a “crab mince.” The whole crabs are put through a deboning machine and ground down to a crab-flavored puree high in protein and calcium. The mince is used as an extender, a thickener or flavoring agent in stuffed pastas, crab cakes, stuffing and soups.

“Nutritionally speaking, it’s a great product, but texturally, it’s not that appealing,” said Skonberg.

The university also has been working on a high-protein low-fat corn puff using the crab mince.

“We originally wanted to make a seafood flavored snack but most of the crab flavor was volatized by the high heat,” said Skonberg. “We ended up using cheddar cheese and sour cream and onion flavors.”

The market for crab mince is very limited, according to Scott Wuerthner, sales manager at Portland Shellfish. His company makes a mince similar to Skonberg’s with the shells and scraps of Jonah and rock crabs, already picked for lump crabmeat.

 “We can sell it for $1.50-$2 a pound, but it’s just not in great demand,” said Wuerthner. “It’s got great flavor, the raw flavor of the animal, but the uses are limited, so a lot ends up in the freezer.” 

Wuerthner said fishermen call every day wondering if there’s a market for green crabs.

“We tell them we don’t want any green crab,” said Wuerthner. “We’re pushed to sell the rock and Jonah, so why would we throw green into the mix, especially when the main reason we sell the mince in the first place is to reduce our waste.”

Don Smith, 72, a lobster dealer at the Prospect Harbor Trading Co., has been buying and selling lobster for nearly 40 years.

“These days, the fishermen are really complaining about green crabs,” Smith said. “Instead of traps full of lobster, they’ll sometimes have whole traps full of green crabs. They’ll just have to turn the trap upside down and dump the thing into the water.

“It used to be the same with urchins ’til they fished those out.”