Transport of blue whiting eggs and larvae: Insights from an Agent-Based Model (ABM)

Recruitment variability in marine fish populations is strongly influenced by climate-driven oceanographic processes, with important implications for ecosystem productivity and fisheries management. Blue whiting (Micromesistius poutassou) is one of the largest commercial fish stocks in the North Atlantic, yet the mechanisms linking climate variability to recruitment remain poorly understood. Previous studies have identified associations between blue whiting recruitment and large-scale atmospheric forcing, particularly wind stress curl (WSC), but the mechanisms behind this correlation remain unclear.
Here, we use an agent-based model (ABM) forced with GLORYS12V1 flow fields to simulate the drift of blue whiting eggs and larvae during the peak spring spawning period. We run simulations for 12 years representing extremes in recruitment (six highest, six lowest), releasing particles from four main spawning areas west of the British Isles that encompass blue whiting major spawning grounds.
Our results show that transport conditions differ markedly among spawning areas and between high and low recruitment years. In particular, we identify two regions where physical transport processes are strongly linked to recruitment success: (1) Porcupine Bank, where larval retention enhances recruitment, and (2) the area west of the Hebrides, where northward dispersal favors successful recruitment. By contrast, other spawning areas show weaker or more variable links between transport patterns and recruitment.
These findings provide mechanistic insight into how regional circulation and climate-driven variability shape recruitment dynamics of blue whiting. They also highlight the importance of considering both retention and dispersal processes in assessing the dynamics of North Atlantic fish stocks under changing climate conditions. More broadly, this study demonstrates how process-based models can be used to bridge physical-biological linkages, contributing to improved understanding of climate-ecosystem interactions and supporting sustainable management of key fisheries in the North Atlantic.