OPTIMAL FORAGING AND HABITAT SHIFT IN PERCH (PERCA-FLUVIATILIS) IN A RESOURCE GRADIENT

Tested whether a simple optimal foraging model could predict 1) the diet breadth of perch and 2) when perch should shift from feeding in the pelagic habitat to the benthic habitat. The smallest size class of pelagic prey used by perch corresponded with what was predicted by the basic prey model, but the mean prey size in the diet of perch was larger than that predicted by the model. For benthic prey, diet breadth was poorly predicted, reflecting the problem of extrapolating laboratory-estimated encounter rates and handling times to more complex habitats in the field. -from Authors