European green crab (Carcinus maenas) dispersal: The Pacific experience

European green crab (Carcinus maenas) dispersal: The Pacific experience

G.S. Jamieson, M.G.G. Foreman, J.Y. Cherniawsky, and C.D. Levings

European green crab (Carcinus maenas) dispersal: The Pacific experienceThis is part of Crabs in Cold Water Regions: Biology, Management, and Economics
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The European green crab, Carcinus maenas (Decapoda: Portunidae), is extending its range much more rapidly on the Pacific coast of North America than it is on the Atlantic coast. This crab was first observed on the west coast of North America in San Francisco Bay in 1989, and by 2001, green crabs had been found in Esperanza Inlet on the west coast of Vancouver Island, about 1,500 km northward. This dramatic rate of range expansion on the Pacific coast to British Columbia may have been facilitated by 1997/1998 El Niño currents, as the crabs found in Canada were all of a size expected of the 1997/1998 year class. Ocean current analyses derived from sea surface elevation anomalies do not indicate likely larval transport via sea level–induced currents after February 25, 1998, but from November 26, 1997, to the former date, north-flowing currents were stronger than normal. Currents resulting from short-term storm event(s) might have also transported larvae, but these were not resolvable from the seasonal satellite altimetry data we considered. However, the wide spatial distribution of green crab occurrences in Canada suggests ocean currents in late 1997/early 1998 were the most likely vector for the first transport of green crab larvae to British Columbia.

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