Growth of Barents Sea capelin (Mallotus villosus) in relation to zooplankton abundance

Abstract

Because capelin feed on zooplankton, the availability of the latter may be a limiting factor for capelin growth in at least some areas and at certain times. It was therefore hypothesized that a relationship exists between capelin growth and zooplankton biomass either in the same year or in the previous autumn. Capelin growth in a given year was more closely correlated with the estimate of zooplankton abundance in the previous autumn than with that in the present autumn. Growth of the youngest capelin was well correlated with abundance of the smallest zooplankton, whereas growth of older capelin was more closely correlated with abundance of the larger zooplankton forms. Various water masses were defined on the basis of hydrographic conditions, and significant differences in the zooplankton content among the water masses were detected. An inverse relationship between zooplankton abundance and capelin biomass was found, indicating that grazing by capelin has a negative effect on zooplankton abundance.