Tidal, diel and longer term changes in the distribution of fishes on a Scottish sandy beach

Abstract

Fishes were sampled by seine and beam trawl over tidal and diel cycles on a sandy beach on the west coast of Scotland in J u n e and August Species composition of the catches of the 2 gear types differed. There was a signif~cant pos~tive relationsh~p between depth (0 to 5 m ) and species richness but a few specles were restricted to depths of < S m Although s~gnif~cantly more species and individuals were caught at night and at low tide there was no evidence for the existence of d~stinct 'day ' and 'night' communities. D~fferences between catches at hlgh and low water were caused by the movement of a few species into the ~ntertidal zone on the rising tide. Diel differences In abundance were pnnc~pally d u e to an inshore migration of several species of gadoids at dusk and movement offshore at dawn. Longer term changes in abundance and distr~bution were attributed to predation and movement ~n t o deeper water