Sagittal otolith shape used in the identification of fishes of the genus Serranus

Abstract

Shape descriptors of saccular otoliths (sagittae) obtained by image analysis were investigated for the identification of three species of genus Serranus inhabiting the Canary Islands. The main of the paper was applied shape descriptors that could explain better the otolith shape differences found among these species. Some descriptors (EllipProffitt, CircProffitt, EllipVoss, TriVoss, ConvexCM1, ConvexCM2, Intrusiveness, Protrusiveness, ConvexJ, EllipLMedS, EllipMom, TriMom, Rectil, RectRobust, SqFFT, SymmL and SymmF) were used for the first time in a biological application as fish taxonomy. The variables were standardized with respect to otolith–fish length and the otolith weight added in the analysis. The standardization of otolith shape variable provided better results with respect to otolith length (82.7% of agreement) versus fish length (72.8%). ConvexR0, Ecc and Protrusiveness were the main shape variables that explain the inter-species variability. However, when the otolith weight was added in the analysis the discrimination was better with respect to fish length (86.4%), being the variable more significant.