The Deadliest Catch: Population Density and Characteristic Study of the Invasive Green Crab (Carcinus maenas)

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Students Involved:

Paige Mooney UNH - Department of Biological Sciences
Maureen Healey UNH - Department of Biological Sciences

Faculty Advisors:

Elizabeth Fairchild UNH - Department of Biological Sciences
The European green crab (Carcinus maenas) is an invasive littoral crab. It is an omnivorous scavenger and a voracious predator with a diet consisting mainly of clams, oysters and mollusks. The green crab is a highly fecund species that is able to tolerate a relatively wide range of temperature and salinity conditions. These characteristics, along with a lack of natural predators, have allowed green crabs to successfully and rapidly colonize along the New England coastline.
Green crabs compete with native flora and fauna for food and habitat, and are therefore harmful to local marine ecosystems. They have had a severely detrimental impact on New England fisheries due to their large-scale predation. Green crabs are principally blamed for the collapse of Maine’s soft shell clam industry, as well as the depletion of various estuarine fish populations. Additionally, their foraging and burrowing activity has done particular damage to eelgrass beds.
In order to maintain the integrity of New England estuaries, it is necessary to restore eelgrass beds and restock populations of organisms that have declined due to green crab predation and activity. However, these endeavors prove to be ineffective if abundance and distribution of green crabs is poorly understood. Increased knowledge regarding the spatial and temporal patterns of green crabs will not only aid in more efficient restoration and restocking efforts, but also provide useful information for future management of green crabs. Our research project consists of two parts: 1) a trap saturation study and 2) a comparison study looking at the relative abundance and physical characteristics of the green crabs within two New Hampshire estuaries: Great Bay and Hampton-Seabrook.


Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant


  • The deadliest catch: population density and characteristic study of the invasive green crab ("Carcinus maenas") (2010). Paige Mooney and Maureen Healey. Advisor: Elizabeth Fairchild.