A Novel Method Utilizing Otolith Outline Analysis for Identifying Fish Species

Fish species can be identified based on the analysis of otolith morphological indices. Common methods used to determine populations or identify species based on otolith morphology analysis include Basic Dimension Parameters (BDP), Shape Indices (ShI), and Elliptic Fourier Descriptors (EFD) indices through various statistical techniques. In this paper, we introduce a novel method to distinguish between otolith morphological groups to identify differences among five commercially important fish species in Vietnam—Sillago sihama, Siganus canaliculatus, Selaroides leptolepis, Johnius carouna, and Otolithes ruber—based on 188 left otolith samples. This method involves the automated calculation of distances from the otolith center to 100 points along its contour, implemented through a Python-based image processing pipeline. This is the first comparison between three otolith morphology analysis methods, including two conventional methods and a new method. The results of this study demonstrated that the center-to-contour distance index is effective for classifying otolith morphology with the aim of identifying fish species. Additionally, the study results reaffirm that otolith morphological analysis is an effective tool for identifying fish species and distinguishing otolith morphological differences among the five species.