Evaluating trapping as a method to control the European green crab, Carcinus maenas, population at Pipestem Inlet, British Columbia

Abstract

The invasive European green crab, Carcinus maenas, has been present on the west coast of Vancouver Island since at least 1998. Annual trapping was conducted between 2010 and 2014 at Pipestem Inlet, British Columbia, Canada to determine if depletion is a potential mechanism to eradicate or control established populations. Catch per unit effort (CPUE) decreased over time within years suggesting depletion was reducing population abundance but this trend was not apparent between years suggesting control measures may be of limited utility over the longer term. For example, there was an increase in population size between 2010 and 2012 despite annual depletion efforts, likely due to good recruitment. Although the effects of depletion efforts on population size are less apparent, these events have significantly altered the demographics of the population at Pipestem Inlet, including decreased carapace width. Also, catch rates generally showed a bias towards female crabs among years. These demographic changes could have implications for the continuing green crab invasion on the west coast of North America, especially northward spread.