Variation in morphometric characteristics between cultured and wild striped snakehead (Channa striata) populations in the Mekong Delta

Abstract

Fish in captive conditions can change their morphology differently from their origin in the wild. Thus, morphological characteristics are commonly used for population identification. In this study, morphometric differences among six cultured and wild populations of striped snakehead (Channa striata) in the Mekong Delta were evaluated. Cultured fish were collected from three hatcheries in Hau Giang, An Giang, and Dong Thap provinces, where snakehead farming is commonly practiced. Wild fish were sampled nearby three conservation areas in Long An, Ca Mau, and Hau Giang provinces. Twenty-two morphometric measurements were converted into ratios to standard length or head length (indices) or adjusted for body size effects by using Elliot et al. (1995) approach. Univariate analyses showed that morphometric characteristics of snakehead were significantly different among six populations (P<0.01). In fact, wild snakehead fish exhibited higher morphological diversity within and among populations compared with the cultured ones. Principal component analyses based on two treated data types consistently indicated that head size and caudal peduncle height were important traits to distinguish wild and cultured populations, regardless of sampling localities. Wild snakehead had longer but smaller head and narrower caudal peduncle than the cultured ones. The morphometric indices-based approach resulted in higher proportions of correct individual assignment (90.7%) than that based on body size-adjusted measurements (79.6%), partly due to body size effects.