Morphological characteristics of otolith for four fish species in the Edremit Gulf, Aegean Sea, Turkey

Abstract

Otolith morphology is important for species identification, fishery management and stock assessment. In this study, otolith (Sagitta) morphology of four fish species viz. Pomatomus saltatrix, Sarpa salpa, Trachurus trachurus, and Belone belone was investigated. The length (mm), width (mm), area (mm2) and perimeter (mm) measurements of the otoliths were made and four different shape indices, including form factor (FF), aspect ratio (AR), roundness (RD) and circularity (Cİ) were calculated. In addition, relationships between total fish length and otolith morphology were investigated. Measurements of sagittal otoliths of four species were obtained by image analysis using tri-ocular microscope. Based on the results, the morphometric measurements and four examined shape factors of otolith varied among species. Coefficients of correlations (r) between total fish length and otolith morphology and otolith length-otolith morphology were generally highly significant (P<0.05) for studied fishes. The results show that the shape indices were significantly different in analyzed species even they indicated a similar pattern with maximal otolith length. These data provide information for species identification using sagittal otoliths in the fossils and diets of fish predators and also will contribute to the region's sustainable fisheries management.