Sediment selection in juvenile plaice and its behavioural basis

In the laboratory juvenile plaice Pleuronectes platessa (13-114 mm) were co nsistently found on the finest of four sediments after 24 h both in the lig ht and the dark. Preference when assessed both by the fish's final position and by the amount of time it spent on each sediment agreed on 72%, of occa sions. Size did not affect preference, which was determined principally by a fish's ability to bury in a sediment. Burial reduces activity and thereby increases the time that fish spend on sediments in which they can bury. Ac tivity level, which is dependent on light intensity and endogenous factors, therefore determines the degree of selectivity shown. Swimming duration an d resting by the largest fish (71-114 mm) did not differ among sediments. F ield experiments produced results similar to those obtained in the laborato ry. (C) 2000 The Fisheries Society of the British Isles.