Coupling survey data with drift model results suggests that local spawning is important for Calanus finmarchicus production in the Barents Sea

Abstract The copepod Calanus finmarchicusis an important part of the diet for several large fish stocksfeeding in the Atlantic waters of the Barents Sea. Determining the origin of the new generation copepodites present on the Barents Sea shelf in spring can shed light on the importance of local versus imported production of C. finmarchicus biomass in this region. In this study, we couple large-scale spatiotemporal survey data (> 30 years in both NorwegianSea and Barents Sea areas) with drift trajectories from a hydrodynamic model to back-calculate and map the spatial distribution of C. finmarchicus from copepodto egg, allowing us to identify potential adult spawning areas. Assuming the adult stage emerges from overwinteringin the NorwegianSea, our results suggest that copepodites sampled at the Barents Sea entrance are a mix of locally spawned individuals and long-distance-travellers advected northwards along the Norwegianshelf edge. However, copepodites sampled farther east in the Barents Sea (33°30′E) are most likely spawned on the Barents Sea shelf, potentially from females that have overwinteredlocally. Our results support that C. finmarchicus dynamics in the Barents Sea are not, at least in the short-term, solely driven by advection from the NorwegianSea, but that local production may be more important than commonly believed.