Sensitivity of Marine Pelagic Fish Catch Potential to Changes in Primary Production in a Global Fisheries Model.

Climate-driven changes in ocean primary production are expected to have cascading effects across marine food webs, yet the sensitivity of marine fish catch potential to primary production variability is rarely incorporated into vulnerability frameworks relative to physical stressors such as warming and deoxygenation. Life-history traits can mediate species sensitivity to environmental change, reflecting evolutionary adaptations to the environmental conditions of their habitats. Using a global fisheries dynamic bioclimatic envelope model (DBEM) forced by alternative primary production projections under identical physical ocean conditions, we assess how the variability in primary production propagates to estimates of maximum catch potential (MCP) for 120 pelagic fish species with diverse life history traits. Sensitivity is quantified using an index defined as the ratio of inter-simulation variability in MCP to variability in primary production. Mixed-effects models are used to evaluate how biological traits and sea surface temperature (SST) influence the sensitivity. SST is the main predictor of the primary production sensitivity index across species within the DBEM modelling framework. Sensitivity index values are highest in cold waters (< 15°C) and decline more than 10-fold across the observed SST gradient, with the strongest attenuation above 27°C. These patterns are consistent with physiological constraints encoded in the DBEM's temperature-dependent formulations. Maximum body size is a significant but modest predictor of sensitivity, for every 10 cm increase in body length, the sensitivity index decreased by 1.5% (95% CI: 0.9%-2.2%). However, biological traits explain only a small proportion of species-level variation in the sensitivity index. Our findings suggest that trait-only climate vulnerability assessments may overlook important temperature-dependent constraints on species sensitivity that emerge from bottom-up energy pathways. Integrating bottom-up pathways and structural uncertainty into species climate risk assessments can improve climate-ready management in systems where production variability is a major driver of catch potential.