MORPHOMETRIC RELATIONSHIPS FOR MOUTH DIMENSIONS AND PREDATOR-PREY SIZE RELATIONSHIPS IN EUROPEAN PERCH, PERCA FLUVIATILIS L., 1758 INHABITING LAKE LADIK, SAMSUN, TURKEY

Abstract

This work aimed to define the morphometric relationships between mouth dimensions, and predator-prey size relationship of European perch, Perca fluviatilis in Lake Ladik (Turkey). The total length (TL), vertical mouth opening (M-V), and horizontal mouth opening (M-H) of each specimen were recorded and predator mouth area (MA) was calculated using ellipse model. Also, total length (PTL) and body depth (PBD) of prey fishes were determined. Total length of European perch and total length of prey fish (European perch; common bream, Abramis brama and rudd, Scardinius erythrophthalmus) were positively and linearly related. The prey size (PTL and PBD) increased linearly with predator mouth size (M-V and M-H), however these parameters increased non-linearly with MA. Prey size in European perch is limited by predator mouth size, which is a linear function of European perch body length. Prey total length (PTL) parameter was better indicator than prey body depth (PBD) for predator-prey relationships. The study provided the first information on predator-prey size and mouth morphometric relationships of European perch population in this lake. These relationships can be useful in understanding the interspecific relationship in food web and estimating the upper size limit of prey available consumed by predator fish.