Age and growth, reproduction and diet of a sublittoral population of the rock goby Gobius paganellus (Teleostei, Gobiidae)

Abstract

Basic biological information for a sublittoral population of the rock goby Gobius paganellus Linnaeus, 1758 is presented based on a 2-year study involving 1680 specimens. The length–weight relationship was given by TW = 0.0089 * TL^3.163 (where TW= total weight in g; TL= total length in mm). Age at length data were inferred by modal analysis of the monthly length–frequency distributions. The parameters of the fitted Von Bertalanffy growth equation (with seasonal component, birth date on the 1st of January) were L _∞ = 13.8 cm; K = 0.73 yr⁻¹; t _o = −0.22 yr; C = 0.95; W = 0.07. This growth rate is much higher than that described for northern Europe populations (where K is about 0.3 yr⁻¹) and is probably associated with a shorter life span. Macroscopic examination of the gonads, and analysis of the monthly values of the gonadosomatic index, indicated that reproduction occurs in winter and early spring, with a maximum in February and March, when water temperatures are lowest. Individuals become sexually mature around 6–7 cm TL, a size that can be reached in less than 1 year. By contrast, individuals of this goby in the British Isles mature in their second or third year. Stomach contents were mainly small benthic invertebrates, predominantly crustaceans.