Research Article: Otolith shape utilization for the stock identification of Caroun croaker, Johnius carouna (Cuvier, ۱۸۳۰) (Perciformes: Sciaenidae), from the east Vietnam sea

Based on the climate hydrology, ecological biogeography, and land–sea interaction relationships, Vietnamese coastal waters can be separated into three coastal zones. In this study, we analyzed the Johnius carouna (Cuvier, ۱۸۳۰) shape of sagittae from several areas along the Vietnamese coast. The morphometric characters of the otoliths were used to identify stock among the fish of different geographic areas. A multistatistics analysis of otolith shapes was applied to estimate the differences between the three regions. Based on the shape indices, wavelet transform and Elliptic Fourier Descriptors (EFD) have signals for division into three groups of otolith shapes (discriminant analysis for wavelet transform: Wilks=۰.۰۶۵, p<۰.۰۰۱ training misclassification error ۹.۸%; discriminant analysis EFD:  Wilks=۰.۰۵۹, p<۰.۰۰۱ accuracies of the classification equal ۹۳.۷۵%; analysis of variance on shape indices: p<۰.۰۵) of the otoliths for the three locations. This study inferred that two distinct stocks were identified, namely Cat Ba and Tho Chu. The individuals from the central zone (Phu Yen) may be a mixing zone between the north and the south, with two possible populations of Cat Ba and Tho Chu.