Size-related shifts in the habitat associations of young-of-the-year winter flounder (Pseudopleuronectes americanus): field observations and laboratory experiments with sediments and prey

Field surveys and laboratory studies were used to determine the role of sub strata in habitat selection by young-of-the year winter flounder. A synopti c field survey of winter flounder and sediments in the Navesink River-Sandy Hook Bay estuarine system in New Jersey demonstrated that winter flounder distribution was related to sediment grain size. Analysis using a generaliz ed additive model indicated that the probability of capturing 10-49 mm SL w inter flounder was high on sediments with a mean grain diameter of less tha n or equal to 0.5 mm, while fish 50-95 mm were least likely to be collected on fine sediments and most commonly on sediments with a grain-size near 1. 0 mm. In the laboratory, sediment preferences and the burying ability of wi nter flounder (15-69 mm SL) were tested by exposing fish in 10-mm size grou ps to a choice of azoic sediments of different sediment grain sizes. Smalle r individuals ( < 40 mm SL) preferred fine-grained sediments while larger i ndividuals ( <greater than or equal to> 40 mm SL) preferred coarse-grained sediments. Burying ability increased with size and all flounders avoided se diments that prevented burial. Subsequent laboratory experiments revealed t hat the presence of live prey (Mya arenaria) can over-ride sediment choice by winter flounder (50-68 mm SL) indicating the complexity of interrelated factors in habitat choice. (C) Published by Elsevier Science B.V.