SS-DBEM ensemble projections of 17 North Atlantic fish species under IPCC AR6 RCP 8.5 climate and MSY fishing scenario

Climate change is reshaping ocean environmental conditions—altering temperature, oxygen levels, acidity, and primary production—which in turn affects the growth, distribution, and abundance of marine species, including those targeted by fisheries. Future predictions of fish distributions and catches models are available, but many do not provide ensembles to account for uncertainty in environmental projections. Furthermore, these environmental projections from biogeochemical models are regularly updated with revision of climate scenarios. The SS-DBEM model is a multi-species model that combines a species-based model (DBEM) with a size-spectrum approach (SS) to project spatially (0.5°×0.5°) and temporally (yearly) resolved changes in marine fish species biomass. It incorporates key ecological processes alongside a competition algorithm that allocates energy resources among co-occurring species using ocean environmental conditions from biogeochemical models. The product was created by determining projections for seventeen species under RCP8.5, biogeochemical ensemble model and FMSY (Fishing Maximum Sustainable Yield). Ensemble change fields were winsorized to limit extreme outliers and transformed using a signed log (log1p) to accommodate negative and zero values. Spatial patterns were then smoothed using a 15x15 cell moving average (terra::focal) to reduce grid-scale noise while preserving large-scale trends.