Environmental controls of fish growth in the southeast Bering Sea

Thesis (M.S.) University of Alaska Fairbanks, 2003Environmental controls of fish growth in the Bering Sea were investigated by examining growth increments and length-at-age. A sea ice-initiated conceptual model of growth that differentiates between food and water temperature controls was proposed. The timing of ice retreat in the region was hypothesized to control food availability by influencing the fate of primary production and inversely affecting prey availability in pelagic and benthic environments. The extent and persistence of ice coverage was hypothesized to influence shelf water temperatures through' cold pool' development. Utility of the conceptual model was assessed through regression and correlation analyses of the growth of two representative pelagic feeding species, walleye pollock and Pacific herring, and two benthic feeders, yellowfin sole and rock sole. The usefulness of herring and rock sole as indicator species of their respective feeding guilds is lessened due to feeding location and diet breadth, respectively. Food availability was shown to be the primary control of fish growth as evidenced by the growth model results of pollock and yellowfin sole and inverse size-at-age time series of these two species. The ecosystem implications of differential fish growth were assessed through investigation of the relationship of growth to condition factor and recruitment