Food of an introduced population of pikeperch, Stizostedion lucioperca L., in Lake Egirdir, Turkey

. Pikeperch, Stizostedion lucioperca L., introduced into Lake Egirdir, in south-western Turkey, in 1955 grew well and formed the basis of an export fishery. Recently their size has declined and there are now so few of filletable size that the fishery has reverted to supplying purely local needs. Only 2 of the original 11 fish species are still found in the lake and this study examined the possibility that the decline in size of the pikeperch might be related to diet. It was found that invertebrates remained the main food of pikeperch in this lake till they reached a much larger size than elsewhere and that cannibalism was much higher than had previously been reported. The indications were therefore that there was a lack of forage fish.