Will the European green crab (Carcinus maenas) persist in the Pacific Northwest?

A strong cohort of young European green crabs (Carcinus maenas) appeared in North American embayments from Oregon to the west coast of Vancouver Island following the strong El Nino of 1997/1998. Unusually, strong north-moving coastal currents transported crab larvae from established source populations in California to the Pacific Northwest. Since then, both coastal transport and recruit- ment of young green crabs have been weaker. Although it was predicted that green crabs would become extinct in the Pacific Northwest once the original colonists died of senescence at about age 6, this has not happened. Age-class analysis and the appearance of young crabs evidence the existence of local recruitment in the Pacific Northwest, especially after warm winters. An extensive survey by Fisheries and Oceans Canada found populations of green crabs on the west coast of Vancouver Island, with densities of .2 per trap in some inlets. However, no green crabs were found in the inland sea between Vancouver Island and the mainland. Therefore, outreach efforts should continue to prevent the establishment of this invader in those waters via ballast water or shellfish transport.