Comparison of trapping methods for invasive European green crab

Abstract

European Green Crab (EGC) (Carcinus maenas) is a voracious aquatic invasive species (AIS) that poses a serious threat to Canada’s marine and estuarine ecosystems on the Atlantic and Pacific coasts. Fisheries and Oceans Canada (DFO), in partnership with stakeholders and Indigenous groups, has developed substantial knowledge of EGC and its trapping. Trapping has been used for early detection, monitoring, research, and physical removal for control. A review of peer reviewed studies and unpublished projects on EGC trapping was conducted to examine different trap types and their usage in Canada and in other locations where EGC have been trapped. Several factors are key in selecting an appropriate trap type based on trapping objectives. Applications of the different trap types, including important characteristics and deployment logistics are provided in a summary table. Trapping is an effective method for early detection and monitoring relative changes in EGC abundances, population dynamics, and native species. Trapping for rapid response and control can effectively reduce EGC numbers and alter population dynamics. Outcomes could include reduction of mean body size of EGC and recovery of impacted native species and habitat, but trapping efforts may need to be sustained. Knowledge gaps and challenges identified include a lack of information on capturing juvenile EGC in Canada and determining effective threshold levels or numbers for control to prevent environmental and fishery impact.