Otolith shape as a tool for representing different growth in young and adult yellowfin tuna (Thunnus albacares, Bonnaterre, 1788)

Abstract

The stock status of yellowfin tuna (Thunnus albacares) (YFT) in the Indian Ocean is currently concluded overfished and is subject to overfishing. The information about the YFT population structure is fundamental for effective fisheries management and conservation. The otolith shape as a tool for estimating population structure is the cheapest technique compared to other methods, such as genetic, parasite, and otolith chemistry, especially for analyzing the large samples. This study investigates the use of otolith shapes to determine the yellowfin stock from two different locations. Data collection was carried out at two locations, namely Kedonganan and Benoa, throughout 2018. Total samples collected from the two study sites were 314 otoliths, but only 147 whole otoliths could be analyzed. Image analysis was performed using ANOVA-like permutation (n=1000 to determine whether the individual can be reclassified to their sample origin. The subsequent analysis is the variations in the shape of the otolith with multivariate statistical methods using cluster analysis with Canonical Analysis of Principal Coordinates. The result shows that the YFT otolith Benoa is significantly different from the YFT otolith Kedonganan with the P-value = 0.0015.