Long-term population trend of northern anchovy (<i>Engraulis mordax</i>) in the California Current system

Abstract Ecosystem function and variability of eastern boundary upwelling systems is linked to the population dynamics of coastal pelagic fish. Developing population dynamics models of coastal pelagic species over many decades has unique challenges, and can benefit from the integration of multiple disparate sources of fisheries and resource survey information. Northern anchovy (Engraulis mordax) are vital trophic links in the food web of the California Current Ecosystem. Previous studies of this anchovy population had relatively narrow temporal ranges or focused on a single data source (e.g. larval abundance data). Here, we combine data sets that have informed previous studies, into one integrated statistical catch-at-age population dynamics model to estimate extended biomass and recruitment trends, providing a comprehensive account of anchovy dynamics from 1965–2021. Our results are consistent with previous biomass estimates but show an earlier peak in the 1970s that coincided with the peak of the US reduction fishery. Our results can facilitate an in-depth analysis of the environmental drivers influencing successful anchovy recruitment, serve to parameterize and evaluate performance of ecological models that mechanistically link the environment and food web to anchovy population dynamics and distribution, and provide the basis for a management strategy evaluation of this anchovy stock.