Lack of genetic differentiation of Kawakawa Euthynnus affinis (Cantor, 1849) in Peninsular Malaysia based on mitochondrial DNA cytochrome oxidase I

Abstract

Kawakawa Euthynnus affinis is a cosmopolitan epipelagic tuna and is regarded as one of the most commercially important tunas in the subtropical and tropical waters of Indo-Pacific region. Regrettably, a lack of information on the stock structure management and conservation of E. affinis populations in Malaysian waters could result in overfishing and perhaps decreasing the stock structure of this marine fish. Thus, for an effective and successful management of the species, an assessment of stock structure based on molecular knowledge is essential. In this current research, genetic differentiation was assessed utilizing sequence analyses of the mitochondrial cytochrome oxidase subunit I (COI) gene. A 632 bp segment of the COI region was sequenced in 114 individuals of E. affinis sampled from two central geographic regions; the Straits of Malacca (M), and the South China Sea (SCS). The results revealed that the genetic distance within and between seven populations of E. affinis from Peninsular Malaysia was extremely low. The overall mean of haplotype diversity (Hd) was 0.6942, while the average nucleotide diversity (π) was 0.0011. The neighbor-joining (NJ) tree revealed that the samples of E. affinis collected from Peninsular Malaysia were clustered into one clade. The outcomes of this study will provide a valuable baseline of knowledge for proper management and conservation of this neritic tuna in Malaysian waters.