Future poleward distribution shifts of community and functional groups in the Barents Sea modelled under different climate and fisheries scenarios

Arctic ecosystems are among the most impacted by climate change globally. To evaluate future spatial distributions of functional groups (FGs) in the Barents Sea, a spatial mass-balance model (Ecospace) was used to simulate future distributions under a combination of 3 climate scenarios (SSP1-2.6 [cool], SSP2-4.5 [intermediate], and SSP5-8.5 [hot]), and 3 fishing effort (E) levels: intermediate, low, and high. The model was driven by monthly 2D surface and bottom temperature, ice concentration, primary production fields, and E time series from 2020 to 2099. Spatial biomass distributions of the community and most FGs shifted mainly northeast with increasing temperature. In the cool and intermediate scenarios, the temperature decreased or stabilised between the 2050s and 2090s, and the centre of distribution of most FGs returned close to the 2020s positions. In the hot scenario, the community shift rate accelerated from 13 (2020s to 2050s) to 23 km per decade (2050s to 2090s). In this scenario, the spread pattern of the distributions depended on the biogeographic category; many Arctic-boreal and boreal FGs showed a greater increase in spread than Arctic FGs from the 2050s to 2090s. Fishing effort levels affected the spreads of spatial distributions but not the distance and directions of shifts. The Northeast Arctic cod (main target species) showed greater spread at lower fishing effort, possibly a density-dependent range increase. Most FGs showed less clear responses to fishing efforts. We conclude that future distribution shifts were largest for boreal groups in hot scenarios, while in intermediate and cool scenarios, groups returned to present distribution patterns.