Stock Structure Analysis of Unicorn leatherjacket, Aluterus monoceros (Linnaeus, 1758) (Tetraodontiformes: Monacanthidae) from Indian Coastal Waters

Abstract

Unicorn leatherjacket, Aluterus monoceros (Linnaeus, 1758), (Teleostei: Monacanthidae) is a marine demersal fish distributed throughout the Indo-Pacific waters and shared commercial landings along the coast of Indian peninsula from east to west. The present study was conducted to understand the stock structure of A. monoceros from Indian marine waters using truss-network and morphometric based multivariate analysis. Fish were randomly collected from major fish landing centres viz., Gujarat and Kerala along the West coast, and Odisha and Tamil Nadu from the East coast of India, torepresent four zones of the Indian Exclusive
Economic Zone (EEZ). A total of 17 landmarks were considered to form 28 truss distances, along with 15 morphometric data, to differentiate potential fish stocks of A. monoceros. Principal component analysis (PCA), linear discriminant analysis (LDA) and
hierarchical clustering based on Euclidean distances of truss measurements were employed to identify stocks along the coastal waters. Univariate ANOVA showed that 22 out of 28 truss distances were significant (p<0.001), while 9 out of 15 morphometric data were significant. The biplot of the first two principal components indicated intermixing of samples from all zones, suggesting absence of discrete stocks. Major body truss measurements of the anterior and caudal peduncle regions contributed significantly to this. LDA functions also showed no evidence of stock separation. The cluster analysis dendrogram depicted that the stocks are distantly located, forming two main clusters among the four fishing locations considered. A uniform management plan is recommended for better harvest of this demersal resource, irrespective of its wide distribution in Indian waters.