Green crabs may devour America's entire seafood buffet. In New England, the crabs (Carcinus maenas) started by pinching scallop and mussel populations. Now the crabs chomp on clams. Fisheries managers fear that the crabs will move onto the king of American seafood, the Maine lobster (Homarus americanus).
"[The crabs'] food preference has systematically moved through all of shellfish resources on a sequence based on convenience," Chad Coffin, president of Maine Clammers Association, told the Bangor Daily News. "When the clams are gone, what are they going to eat? People may think lobsters are big and tough, but they're not."
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On the other side of the continent, invading hordes of green crabs devour oysters and other crab species, including the delicious Dungeness, in the waters off Oregon and Washington.
Green crabs lack the claw strength to crack into full-grown oysters and other marine mollusks. Instead, the crabs dig young oysters and clams out of up to six inches of sand. The invaders can consume 40 half-inch clams per day, according to the Washington Department of Fish and Wildlife.
Cold waters used to keep lobsters and other marine life relatively safe from the green crab invasion. The crabs are native to the coastal waters of Europe warmed by currents flowing north from the tropics. Chilly winter waters on the East Coast of North America used to knock out invasive green crab populations periodically.
However, as the ocean's temperature increases the green crab killing chills occur less frequently and the invaders' numbers are skyrocketing.
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Unfortunately, the booming green crab population won't make for discount crab legs. Although they are edible, the green crab has little meat and getting at that meat takes a frustrating amount of effort, according to the Sustainable Ecosystems Institute. Research at the University of Maine studied the feasibility of mechanically processing the crabs and making breaded cakes from them.
Despite the difficulties in preparing them for people, green crabs make great fish food. For example, anglers use them as bait. Meanwhile, a project in Canada is working to make fish food out of green crabs for use in the aquaculture industry.
IMAGE: A green crab, also known as a shore crab, Carcinus maenas (Hans Hillewaert, Wikimedia Commons)