Understanding factors influencing Atlantic herring (Clupea harengus) recruitment: From egg deposition to juveniles

Recruitment is a critical component of population dynamics and variability in recruitment underpins large fluctuations in population abundances of commercially valuable marine fishes. Marine pelagic fishes such as Atlantic herring (Clupea harengus) experience relatively high variability in recruitment that is driven by a wide range of biotic and abiotic factors. The relative importance and interaction of each factor for determining recruitment is poorly understood, and consequently, recruitment estimates are one of the largest uncertainties in fisheries management and predictions of future population sizes. Poor recruitment of Atlantic herring has been identified as a major issue and bottleneck for the species; therefore, factors influencing successful recruitment are of great interest to fisheries managers. Here we review studies that have examined the factors influencing survival at the egg stage, early larval stage, late larval stage, and juvenile stage to develop a more comprehensive understanding of the recruitment of Atlantic herring and provide recommendations to guide future research. We identified nine biotic and eight abiotic factors that have been found to substantially impact the recruitment of Atlantic herring, with temperature, prey availability, and predation being the most commonly investigated factors. We conclude it is not one factor that primarily determines recruitment, but rather a collection of many factors that vary temporally and spatially that drive the large variation observed in Atlantic herring recruitment year over year. A holistic approach is required to better understand recruitment and improve fisheries management decisions regarding Atlantic herring.