| Affiliation: | (1) Zoology Department, Oregon State University, 97331-2914 Corvallis, OR, USA;(2) S.P. Cramer and Associates, Inc., 97030, 600 NW Fariss Road, Gresham, OR, USA;(3) Science Applications International Corp., Suite 110, 98011, 18706 N. Creek Parkway, Bothell, WA, USA;(4) United States Department of Agriculture/ARS, Hatfield Marine Science Center, 97365, 2030 S.E. Marine Science Dr., Newport, OR, USA;(5) WDFW, 98501, 600 Capitol Way N., Olympia, WA, USA |
| Abstract: | During the summer of 1998 a new year class of the invasive European green crab, Carcinus maenas, appeared in Oregon and Washington estuaries as well as in northern California, USA, and on Vancouver Island, Canada. This invader was first discovered in San Francisco Bay almost a decade earlier and by 1995 it had spread to northern California. The coast-wide colonization event we studied in 1998 (El Niño cohort) was correlated with unusually strong north flowing coastal currents from September 1997 to April 1998. Larval transport by ocean currents from established populations to the south appeared to be the mechanism for the colonization. Crabs from the 1998-year class grew faster than counterparts from Maine and Europe, averaging 14 mm in carapace width in June, and 46 mm by September 1998. By the end of their second summer, males ranged from 52 to 80 mm in carapace width, and by fall of 2000 some males attained a carapace width of over 90 mm. The life span for C. maenasit in Oregon, Washington and British Columbia is estimated to be similar as in Europe and Maine: 4–6 years. Even though the initial colonists (98-year class) are dying of senescence, and coastal currents have not been favorable for larval transport from source populations in California, green crabs do persist in Oregon and Washington estuaries. It appears that local reproduction and recruitment in some years is high enough to keep this population from going extinct. |
