Ocean-climate conditions and spawner biomass affect the survival of blue whiting early-life history stages

Blue whiting (BW) recruitment has shown wide fluctuations since the early 1980s. Hitherto, no models have accurately explained these past recruitment variations, potentially due to the lack of studies addressing BW stock dynamics in relation to large-scale oceanographic processes. Here we hypothesize that the wind stress curl (WSC) may affect recruitment through several potential mechanisms and through a lagged effect on basin-scale oceanographic properties. In particular, the long-term mean location of the transition zone between areas having positive and negative WSC (WSC zero-line) coincides with the largest BW spawning area in the Northeast Atlantic. We assess the relationship between WSC variability in the zero-line region and a BW recruit survival index between 1981 and 2021. We found that coupling stock-recruitment relationships to WSC variability significantly improves the prediction abilities and forecast horizon of BW survival. It also suggests new processes driving BW recruit survival which could inform sustainable, ecosystem-based management practices for this important fishery resource.