Stock structure analysis of the white-spotted spine foot fish (Siganus canaliculatus) along the Indian coast using Truss morphometry

The white-spotted spine foot, Siganus canaliculatus is a reef-associated pelagic fish widely distributed and consumed all along the Indian waters. The purpose of this study was to examine the stock structure of Siganus canaliculatus using truss morphometric data. A total of 434 specimens were collected from four different fish landing centers along the Indian subcontinent, namely Mangalore, Vizhinjam, Mandapam, and Vishakhapatnam. Morphological data including 28 truss distances were measured for each specimen and these data were subjected to analysis using several multivariate methods such as Principal component analysis (PCA), Discriminant function analysis (DF), and Hierarchical cluster analysis (HCA). The PCA results demonstrated that the first two components (PC1 and PC2) accounted for over 52.6% of the total morphometric variance (PC1%-37% and PC2%-14%). PC1 and PC2 represented the posterior abdomen and the caudal peduncle region of the fish, and both components exhibited a positive correlation. The DF analysis identified 15 out of 28 variables as effective discriminators among the different locations. Additionally, the cluster analysis revealed the existence of two distinct stocks within the four samples groups. Specifically, the Vishakapatnam samples formed group I, forming a separate cluster while the remaining three samples were grouped together as group II indicating a common cluster. The result of DF and HCA confirmed the presence of different stocks of Siganus canaliculatus across the Indian coast