Retrospective quantification of estuarine feeding activity by coastally caught marine fishes

At the population level, there was evidence for estuarine contributions to muscle tissue in both species (means from 16.37% to 61.28%), though among-individual variability was considerable. δ13C and δ34S model outputs implied different estuarine contributions for the same individual, likely reflecting the slower turnover of δ34S than δ13C. Sole exhibited population level plasticity in their feeding as juveniles, separating into two distinct juvenile sub-populations; but they are less plastic as older fish when they adopt increasingly marine diets. Whiting show individual plasticity as both juveniles and adults, feeding on prey of estuarine and coastal origin.