Morphometric multivariate analyses reveal population structuring of Pennahia aneus (Acanthuriformes: Sciaenidae) in Malaysian waters

Pennahia aneus is a commercially important demersal sciaenid fish found in the Indo-Pacific region, yet its population structure in Malaysia remains insufficiently documented. This study aimed to differentiate four populations of P. aneus in Peninsular Malaysia and Borneo using morphometric multivariate analyses. A total of 423 samples were obtained from 22 landing sites across the South China Sea, Celebes Sea, Sulu Sea, and Strait of Malacca. Eleven morphometric characteristics were measured and used for the analyses. Principal component analysis (PCA) revealed minimal variability in body shape and size due to significant overlap among groups. Hierarchical cluster analysis (CA) identified two broad morphological groups: the South China Sea population and the Strait of Malacca-Celebes-Sulu Sea population. This pattern of grouping was reinforced by discriminant function analysis (DFA) and uniform manifold approximation projection (UMAP). The most distinctive morphometric traits for differentiating P. aneus populations were eye depth (ED), snout length (SnL), caudal peduncle depth (CPD), and head length (HL). The classification accuracy for these populations was 71.65%. This study provides the first comprehensive insight into the structured population of P. aneus in Malaysia, offering valuable information for conservation and sustainable resource management. However, molecular validation is necessary to refine the population structure further and strengthen effective management strategies.