Displacement of Green Crabs (Carcinus maenas) by Asian Shore Crabs (Hemigrapsus sanguineus) at Two Locations in Northeastern Massachusetts

Carcinus maenas (European Green Crab) was first discovered on the mid-Atlantic US coast in 1817, and became the dominant crab in estuarine and rocky intertidal locations throughout New England and beyond. A second species, Hemigrapsus sanguineus (Asian Shore Crab), introduced to the New Jersey area of the Atlantic coast around 1988 and first seen in Massachusetts around 1999, has now largely displaced Green Crabs in rocky intertidal areas. This study assessed the population characteristics of the 2 species in 2 different rocky intertidal areas in northeastern Massachusetts via surveys between June 2019 and April 2021. Asian Shore Crabs were by far the more numerous species, representing over 90% of the crabs collected at both locations, where Green Crabs formerly were dominant and abundant.