Seabird survival as indicator of sustainable capelin fishery management

Seabird populations are declining globally, in part due to a combination of climate change and fishery-related pressures. While the impacts of bycatch are well documented, empirical evidence for population effects of prey depletion by commercial fisheries is limited, particularly in systems where forage fish are managed conservatively. Therefore, evaluating whether existing management frameworks are effective at maintaining prey availability within ecologically safe limits presents an important, but underdeveloped, component of ecosystem-based fisheries management. We assessed the effectiveness of Barents Sea capelin (Mallotus villosus) fishery management in sustaining seabird populations, by modelling relationships between fisheries landings, prey availability, climate variability, and seabirds’ adult survival. Using a path modelling framework, we integrated spatio-temporal data on capelin landings, prey abundance, and sea surface temperature across seabirds’ distributions with long-term demographic data from eight breeding populations of four pelagic seabird species. Direct negative associations between capelin landings and adult survival were only detected in one population, corresponding to the strongest spatial overlap between this population’s pre-breeding distribution and areas with high capelin harvest. Survival responses to prey availability and ocean temperature otherwise varied among species and populations, reflecting differences in their foraging ecology and space use. Krill abundance was positively associated with survival in two populations, while warmer autumn temperatures were linked to reduced capelin abundance, indicating climate-driven bottom-up effects. By focussing on adult survival as a response, a demographic rate to which seabird population trajectories are particularly sensitive, our results suggest that current capelin management has limited adverse effects on seabirds under contemporary environmental conditions. More broadly, this study demonstrates that seabird survival has the potential to be used as an indicator of management effectiveness due to its sensitivity to multiple environmental factors and its potential impact on population trends. This study highlights the potential for integrating seabird survival into ecosystem-based fisheries management through long-term monitoring and high-resolution fisheries data.