Predicting herring recruitment from young-of-the-year densities, spawning stock biomass, and climate

Because fish are key organisms in most aquatic ecosystems, we seek to understand what determines their highly variable reproductive success. From our work, it appears that year-class strength of Baltic Sea herring (Clupea harengus L.) can be predicted from young-of-the-year densities in a small coastal area (hydroacoustic data), a climate index (the North Atlantic Oscillation), and the spawning stock biomass. These three factors explained 93% of the variation in the number of age 2 herring during 1985-2000. By predicting year-class strength 3 yr before the fish enter the fishery, we provide managers with the opportunity to adjust fishing pressure per upcoming year classes and manage the fishery by multiannual catch quotas.