The Use of Otolith Biometrics Found in the Stomach of Purple-spotted Bigeye (Priacanthus tayenus Ricardson, 1846) for Food Type Identification of the Makassar Strait, Indonesia

Identification of the type of food of purple-spotted bigeye (Priacanthus tayenus) is very important to analyze the dynamics of the ecosystem and trophic interaction patterns in tropical waters. The main obstacle in the study of feeding patterns is the difficulty of identifying prey species due to soft tissue degradation in the digestive tract. This study aims to analyze the use of otolith biometric parameters in identifying the type of food of purple-spotted bigeye caught in the waters of the Makassar Strait, Indonesia. The samples used were 45 purple-spotted bigeye collected from the fish landing site. Stomach content analysis was conducted with a focus on otolith type as the primary indicator of prey identification. The results were then compared with a reference collection of otolith atlases to identify the otolith type, fish name, and scientific name. Biometric calculations were then performed on intact and paired otoliths. The identification results for otolith type and shape were analyzed descriptively and narratively. The otolith shape parameters studied included form factor (FF), roundness (RO), circularity (C), rectangularity (R), ellipticity (E), aspect ratio (AR). The results showed that the combination of the six parameters was able to distinguish otoliths from various prey species. The prey families that were successfully identified included Mullidae, Ariidae, Apogonidae, Cynoglossidae, Moringuidae, Plotosidae, Synodontidae, Gobiidae, Ambassidae and Leiognathidae. The roundness and circularity variables were the most sensitive indicators in distinguishing species that had similar otolith morphology. These findings prove that biometric analysis of otoliths is an effective method for identifying the type of food of purple-spotted bigeye so that it can improve the accuracy of trophic ecology studies of demersal predators in the Makassar Strait waters.