Snow crab (Chionoecetes opilio) in the Barents Sea — A passive or problematic invader?

The invasion and continued expansion of snow crab in the Barents Sea have provided the area with a new and valuable resource. On the negative side, this invasion may lead to changes in the ecosystem, including structural changes and shifts in energy pathways, as we generally view invaders as a problem. We investigated potential effects of snow crab invasion by applying an end-to-end ecosystem model under different scenarios of fishing and food availability. Overall, the model indicated a low negative impact of snow crab on the ecosystem in the region, also in a potential future with a much higher snow crab biomass. Although snow crab may be found to have local negative effects on specific benthic species, in general it appears that they have found a vacant ecological niche in the Barents Sea ecosystem. In addition, network analysis show that the food web of the Barents Sea becomes slightly more complex when including the snow crab, adding predator–prey interactions. By introducing more parallel foodpaths to the food web, this results in a more resilient ecosystem. Model simulations where the availability of prey to snow crab, and lack of fishing pressure maximizes snow crab abundance result in a somewhat increased impact on the food web. Nevertheless, the effects are still minor and there is no indications that the existing commercial fisheries for other species will be significantly affected. Hence, their role as a passive invader should be considered when structuring management responses.