Stochastic Modelling to Assess External Environmental Drivers of Atlantic Chub Mackerel Population Dynamics

The population dynamics of small and middle-sized pelagic fish are subject to considerable interannual interdecadal fluctuations in response fishing pressure natural factors. However, the impact environmental forcing on these stocks is not well documented. Moroccan Atlantic coast characterized by high variability due upwelling phenomenon, resulting a significant abundance variation catches species. Therefore, understanding evolution stock its relationship with different oceanographic conditions key issue for fisheries management. because limited availability independent-fishery data along coast, there lack knowledge about dynamics. main objective this study test correlation between environment trends estimated assessment model that does need biological information growth, reproduction, length or age structure as input. To achieve objective, fishery analyzed stochastic surplus production able assimilate from surveys landings biomass trend estimation. Then, second step, outputs correlated (physical biogeochemical) variables order assess influence drivers This two-step procedure applied chub mackerel where all available datasets have been used together before. analysis performed showed larger estimates linked periods lower salinity, higher chlorophyll, net primary production, nutrients, subsurface oxygen, i.e., an enhanced strength upwelling. In particular, acute anomalies observed southern part presumably corresponding wintering area species region. results indicate powerful procedure, although important limitations, deepen our spatiotemporal relationships area. Moreover, once identified, they could be generate mathematical simulate future diverse scenarios.