SEAwise synthetic summary report of the findings of WP4 on changes to the ecosystem impacts of fishing in response to spatial management for online tool

The SEAwise project works to deliver a fully operational tool that will allow fishers, managers, and policy makers to easily apply Ecosystem Based Fisheries Management. This SEAwise report synthesises ecological impacts of fishing on retained species, ETP species, habitats and foodwebs by linking the impacts to specific gears and fleets, the status of the impacted species and the species landed by the fleet. Estimated risk to non-retained species focuses on effects on benthic habitats, bycatch of marine mammals, seabirds and reptiles and competition for forage fish between fisheries, seabirds and marine mammals. The evaluation integrates the impact of small- and large-scale fisheries using active or passive gears relative to commonly referenced thresholds for sustainability. The likely change in status or risk under different management and climate scenarios are evaluated for retained species, non-retained bycatch species, seafloor habitats, foodwebs and fisheries related litter in the Mediterranean, Bay of Biscay, Celtic Seas and the North Sea. The management scenarios investigated included fishing scenarios with different effort levels, closed areas and changes in relative effort of passive and active gears. We investigated whether scenarios with a higher proportion of landed stocks in good status also had a higher proportion of other ecological indicators in good status and the degree to which more restrictive, and risk adverse, management scenarios provided lower yields under current or future climate scenarios.

In the North Sea and Celtic Seas, more landed stocks in good status coincided with a higher proportion of other ecological aspects in good status, whereas in the Bay of Biscay and Adriatic and western Ionian Sea, the two were unrelated. Climate change had minor effects on the attainment of GES and management strategy remained the determining factor for both attaining GES and the resulting yield. Almost all management strategies except current management led to overall decreases in effort and as a result, the general ecosystem impact to a level where GES was attained (habitats and foodwebs) or the impact was decreased by at least 20% (bycatch). While the attainment of GES could also be found in scenarios with closed areas, this was generally restricted to the indicators at which the closure was aimed while other indicators worsened.

Decreasing fishing effort to levels compatible with FMSY-min resulted in slightly but not significantly higher average landings in the Adriatic and western Ionian Sea and the North Sea under current climate where currently overfished gadoid stocks were rebuilt in the simulations. However, in the other areas, average landings by fleet declined by 27% to 46% as choke species limited catches. Hence, a transition to strict MSY management will not release further yield unless it is attained through implementation of gear and fishing practices aimed at avoiding choke species. The decline in yield and the increase in the proportion of ecological indicators in good status were linked in the Adriatic and western Ionian Sea and the Celtic Sea while in the Bay of Biscay and North Sea there was no direct link between the two. Hence, it cannot generally be concluded that attainment of GES comes at the cost of yield. However, future warming and a transition to strict MSY management will lead to declining yield in all regions; due either to the climate independent effect of choke species or climate induced declines in productivity.