About the Project
The invasive European green crab (Carcinus maenes) has been a destructive force in the northern Gulf of Maine for several years, clearing estuaries of eelgrass as they dig up clams, and destabilizing marsh banks with their burrows. Initiated in 2013 by PIE-Rivers partner MassBays and the “Eight Towns and the Great Marsh” program, the Towns of Ipswich, Rowley, Essex, Newbury, and Gloucester have engaged in trapping of the green crabs based on a $0.40 per pound bounty funded by the MA Division of Marine Fisheries and the Town of Ipswich.
Over the past few years, MassBays Coordinator Peter Phippen has helped develop monitoring protocols to track the crabs and evaluate their impact in Massachusetts. Spring 2015 trapping efforts in the Great Marsh revealed the green crab populations were significantly diminished from 2014 levels, possibly due to the combination of an extremely cold and ice-laden 2014/2015 winter and extensive late-season (2014) trapping effort by area communities. Green crab populations began to recover through Summer 2015 (see graph below), culminating in a crab-per-trap average for December of double that of the often more prolific season of late Summer/Fall.
The North Shore monitoring protocols are now in use by MassBays South Shore program. Preliminary data from a burrow survey on the North and South Rivers (in six Scituate, Marshfield, and Norwell salt marshes) show similar results to the North Shore, with hole diameters ranging widely from 0.5cm to 6.9cm, and most burrows in the 1-2.5cm size range (data depicted in the histogram below).
To date, more than 100,000 lbs. of green crabs have been removed from the system, and the project continues to move forward. Efforts were given an important boost in 2016 with funding secured by Representative Hill and Senator Tarr and the Division of Marine Fisheries.
Throughout Plum Island Sound and Essex Bay