Green crab, Carcinus maenas. (Photo Credit: Lmbuga CC BY-SA 3.0)
Voracious invading green crabs pose threat to local shellfish
Friday, August 30, 2013, 23:50 (GMT + 9)
An invasion of greedy green crabs (Carcinus maenas) along the coast of Maine has worried the locals and prompted a survey to control them more effectively.
This crab species, which is native to Europe and are believed to first arrived in New England in the 1800s probably in a sailing ship's ballast water, has overtaken the space belonging to the local soft-shell clams and has threatened other local shellfish.
Traps set by volunteers along the coast of Maine will help gather data which will then be used to raise public awareness so that coastal towns greeted by the invasion can take effective measures to keep the green crabs under control.
Green crabs are not commercially viable since they have little meat, unlike their other two local counterparts, the Jonah crab (Cancer borealis) and the rock crabs (Cancer irroratus), indigenous to Maine. Global warming and therefore warmer ocean waters have caused the green crab numbers to increase dramatically in the past several years all along the American East Coast, from Virginia to Newfoundland.
In Casco Bay, the green crabs have wiped out the entire clam population and are threatening the local scallop, mussels and other shellfish, informed Pat Keliher, Marine Resources Commissioner of the area.
Keliher believes that installing fencing, setting traps or even using the green crabs as lobster bait could help restore the balance of the marine ecosystem by protecting the clams and boosting their population while reducing the green crab numbers.
The crabs also pose a threat to local lobsters as well as decimating eel grass, a protective habitat for several other local marine species.
At present, there is research being done on making the green crabs commercially viable by turning them into aquaculture feed, a compost supplement or a food additive.
Clams are the third most lucrative commercial fishery in Maine and their industry yields over USD 15 million every year.
By Gabriela Raffaele