Density-Dependent Growth of Silver Hakes

Abstract

Abstract The growth rate of the silver hake Merluccius bilinearis in the northern Georges Bank-Gulf of Maine stock appears to be highly density-dependent after fish reach the size at which they become piscivorous. The correlation between mean weight of age-2 through -5 fish and three estimates of relative stock density (catch per unit effort CPUE from commercial vessels, and virtual population analysis VPA of biomass and abundance) for the period 1962–1979 was analyzed by regression and Spearman rank correlation analyses. Mean weight at age was significantly and inversely correlated with estimates of stock density for all ages, although correlation coefficients were markedly lower for age-2 fish than for older age-groups. The lower correlation for age-2 fish may be due to reduced feeding competition with the adult stock, because silver hakes feed almost entirely upon invertebrates until becoming piscivorous after reaching 20–30-cm fork lengths between ages 1 and 2. Mean weight of age-2 fish was not correl...