Green crabs: Bad for the pond, good for the palate

Thu, 07/18/2019 - 5:45pm
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“Eat the invaders” was the theme of the day on Tuesday, July 9. Which invaders? The European green crab. For the Block Island Shellfish Commission, the theme enhances their mission: beat back the predatory crabs that have invaded the Great Salt Pond, disturbing the habitat for other, native shellfish, and that has also, perhaps, hastened the decline in soft-shell clams.

Green crabs have been the subject of several Shellfish Commission meetings over the past months. Member George Davis has taken the lead in researching what can be done to reduce the population. His efforts led him to attending a conference earlier this year in Maine, and while there he connected with scientists at Green Crab R&D.

“It’s going to take a lot of learning,” said Davis at the meeting, and to that end, he had invited Marissa McMahan, Ph.D. also of the Manomet organization on Cape Cod, to attend the Commission’s meeting and to speak on the subject at the Block Island Maritime Institute’s Tuesday night lecture series, followed by a cooking demonstration and tasting by Thanh Thái, co-author of Green Crab R&D’s “The Green Crab Cookbook.” On the menu: fried soft-shells and a Vietnamese crab soup.

McMahan did not come alone. She and a fellow fisherman — McMahan comes from a lobstering family — earlier in the day spent time with Davis and Block Island aqua-culturist Catherine Puckett teaching them how to identify when the green crabs have entered their pre-molt stage. In the four crab traps they inspected, they found about 30 such crabs.

Identification is key because cooked in the soft-shell stage, the crabs are at their most lucrative. There’s a “centuries-old green crab fishery” in Venice, Italy, where soft shells go for about $55 per pound, said McMahan. Deep-fried soft-shell crabs are a delicacy in Venice. In Maine, restaurants have been paying $3 per crab. They get them live, not frozen, and evidently they’re willing to take as many as they can get. “We know the market is there” said McMahan, “but we need to build the supply.”

Identifying that pre-molt stage is key – from there it will be about two to three weeks before the crabs molt, and they are isolated in individual “crab condos” within floating lobster cages until they do. Once they molt, there is only about a 24-hour window until the crab starts forming its new shell.

Just when the crabs molt is still a question. Davis said that most of the crabs they had looked at appeared to have already molted. McMahan estimated that the peak for crabs molting on Block Island might be in June.

Green crab roe is also a delicacy and has been compared in taste and quality to urchin roe. But there are other, far simpler ways to enjoy the crabs. One way of course is to steam and then shuck the meat out of the crabs, but it’s labor intensive, and due to the crab’s relatively small size, there isn’t a lot of meat per crab. Far simpler is to utilize the whole crab to make a stock that can then form the basis for many other dishes, including seafood soups, stews, and risotto.

The stock recipe on Green Crab R&D’s website calls for at least one pound of green crabs, water, and salt. Herbs and spices are listed as optional. Enough water to cover the crabs with an inch of water is brought to a boil in a pot with a pinch of salt. Meanwhile, rinse the crabs in cold water. When the water boils, add the crabs and boil until the shells turn red. Turn the burner off and crush the crabs. The website recommends using “a mallet, rolling pin, or similar object” to crush the crabs. This will release more flavor. At this point, you may add any spices or herbs you wish. Simmer the whole for about 15 minutes and then strain through a fine sieve. Let cool until ready for use.

More free recipes may be found at greencrab.org, where there is information about green crabs and a cookbook. Thái also has a blog called Green Crab Café (greencrabcafe.com) with even more recipes — including some utilizing sugar kelp — another crop being developed in the northeast, including here on Block Island. (Puckett harvested her first sugar kelp crop in April on her experimental farm in the Great Salt Pond.)

To entice the general public to utilize the crabs, the Harbor’s Department is giving out brochures at the Harbormaster’s Shack (where shell fish licenses are sold) on green crab identification. Members of the Shellfish Commission, along with Puckett, are reaching out to local restaurants, chefs, and purveyors of shell-fishing equipment on Block Island to spread the word: Green crabs are good to eat.