Abundance and spatial overlap of gobies (Gobiidae) in Lough Hyne, Ireland

Abstract

The densities of gobies (Gobiidae, Pisces) were counted by scuba divers on 13 sublittoral transects in Lough Hyne, southwest Ireland. The characters used for underwater identification are described. Densities ranged up to 6.5 m−2 for Pomatoschistus pictus (Malm), 4.0 m−2 for Gobiusculus flavescens (Fabricius), 0.9 m−2 for Gobius niger L., 0.3 m−2 for G. cruentatus Gmelin, and 0.3 m−2 for Thorogobius ephippiatus (Lowe), while G. paganellus L., G. couchi Miller & El-Tawil and Lesueurigobius friesii Malm were rare on the transects. Gobius cruentatus and T. ephippiatus were largely confined to holes under rocks, while P. pictus and G. niger were most abundant on more open terrain. G. flavescens was hyperbenthic and largely confined to water less than 5 m depth. Significantly less P. pictus, G. flavescens and G. niger were recorded at night, and ‘sleeping’G. flavescens were observed. A working model of the spatial overlap of gobies in Lough Hyne is presented, and the possible roles of diet, predation and temporal activity patterns in interspecific competition are discussed.