Spatial growth variability in marine fish: example from Northeast Pacific groundfish

摘要

Marine fish populations exist in a complex environment, with oceanographic and fisheries factors affecting their dynamics. It has been shown that life history characteristics of marine fish vary in space and time. We examined spatial variability in growth of eight groundfish species in the Northeast Pacific Ocean to identify shared spatial patterns and hypothesize about common mechanisms behind them. Growth parameters were estimated in different areas over the latitudinal range of the species, and several hypotheses were tested as to how these parameters vary along the US west coast. Clear differences in spatial growth variability emerged among the species examined. Shelf species exhibit the highest growth rate between Cape Blanco and Cape Mendocino, which may, in part, be attributed to area-specific upwelling patterns in the California Current ecosystem, when nutrient-rich deep water is brought to the surface south of Cape Blanco and is uniquely distributed throughout this area, providing favourable conditions for primary productivity. Slope species showed a cline in asymptotic size (L-infinity), with L-infinity increasing from south to north. This cline, previously attributed to fishery removals, also fits a specific case of the widely described Bergmann's rule, and we explore specific potential ecological mechanisms behind this relationship.