Stock Discrimination of Northern Pike Esox lucius L., 1758 Inhabiting Lakes Simenlik and Ladik (Samsun-Turkey) Using Otolith Biometry and Shape Analysis

Abstract

This study was carried out to investigate the relationships between total length and otolith dimensions and to detect the otolith shape index values of Northern pike (Esox lucius) which has high economic value, sampled from Ladik and Simenlik Lakes. A total of 140 specimens (Lake Ladik: 82 individuals, Lake Simenlik: 58 individuals) were sampled. Otolith height, length, perimeter, and area were determined by Imaging Software. Nonlinear and linear models were applied to estimate the relationships between the otolith measurements and total length. Form factor, circularity, roundness, rectangularity, aspect ratio, and ellipticity were used for otolith shape analyses. It was found that the relationship between the total length-otolith length was found to have the highest r2 value (Lake Ladik r2=0.949, Lake Simenlik r2=0.914) among the total length-otolith morphometrics at both localities. Otolith shape indices were calculated by using otolith measurements. As a result of comparing shape indices, it was found that there was a significant difference in two localities using roundness, ellipticity, and aspect ratio (P <0.05). The results indicated otolith shape indices could be used as a suitable tool to discriminate Northern pike populations.