Spatial dynamics of anchovy, sardine, and hake pre-recruit stages in the California Current

Abstract

Three genera, Engraulis, Sardinops, and Merlucciu have coincident spawning and juvenile brood areas in most eastern and western boundary currents throughout the world. The CalCOFI survey program has amassed a 50-year data series on location and timing of spawning and the resultant recruitment of anchovy, sardine, and hake in the California Current region. Use of existing Lefkovitch matrix population projection models for these three species allows evaluation of the spatial and temporal scales that govern the biological and physical interactions. We present rate diagrams for hake and construct comparable diagrams for anchovy and sardine in a common, variable environment. Rate diagrams depict the relative importance of demographic (natality and mortality), growth, and kinematic (passive and active movement) processes to a quantity of interest as a function of spatial and temporal scale. Results confirm that the scale of observations will have to be manipulated to expose the importance of any combination of processes for life history stages among these species. Field sampling systems have not yet responded adequately to mesoscale features (50 km) persisting over months.