Population Genetic Structure of Ornate Threadfin Bream (Nemipterus hexodon) in Thailand.

Verakiat Verakiat Supmee,Pradit Pradit Sangthong,Apirak Apirak Songrak,Juthamas Juthamas Suppapan

doi:10.21315/tlsr2021.32.1.4

Abstract

Ornate threadfin bream (Nemipterus hexodon) is an economically important fishery species in Southeast Asia. In Thailand, N. hexodon decreased dramatically due to overexploitation for commercial purposes. To construct an effective sustainable management plan, genetic information is necessary. Thus, in our study, the population genetic structure and demographic history of N. hexodon were investigated using 419 bp of the mitochondrial DNA sequence in cytochrome oxidase subunit I gene (mtDNA COI). A total of 142 samples was collected from nine localities in the Gulf of Thailand (Chonburi, Samut Songkhram, Surat Thani, Nakhon Si Thammarat, Songkhla), and the Andaman Sea (Satun, Trang, Krabi, Phang Nga). Fourteen polymorphic sites defined 18 haplotypes, revealing a high haplotype diversity and low nucleotide diversity among nine localities. The analysis of molecular variance (AMOVA) analysis, pairwise FST, and minimum spanning network result revealed that the genetic structure of N. hexodon was separated into two populations: the Gulf of Thailand and the Andaman Sea population. The genetic structure of N. hexodon can be explained by a disruption of gene flow from the geographic barrier and the Pleistocene isolation of the marine basin hypothesis. Neutrality tests, Bayesian skyline analysis, mismatch distribution, and the estimated values of population growth suggested that N. hexodon had experienced a population expansion. The genetic information would certainly help us gain insight into the population genetic structure of N. hexodon living on the coast of Thailand.

Highlights

Ornate threadfin bream (Nemipterus hexodon) is a demersal fish, widely distributed in the Indian Ocean to the Pacific Ocean
From the genetic structure result in the study, we suggested that the implication to the management of the N. hexodon population in the Gulf of Thailand and the Andaman Sea should be managed as distinct units because each population carries a unique genetic structure
Our study showed that the population genetic structure of N. hexodon living along the Thailand coast was separated into two populations: the Gulf of Thailand and the Andaman Sea

Summary

Introduction

Ornate threadfin bream (Nemipterus hexodon) is a demersal fish, widely distributed in the Indian Ocean to the Pacific Ocean. It is a principal catch species in the trawl fishing in Southeast Asia (Russell et al 2016; Stobutzki et al 2006). The meat of N. hexodon has a white colour and it has better gelling than the redfleshed fish (Hastuti et al 2017). In Thailand, this species is widely used for surimi production (Nalinanon et al 2011). 52,000 tons/year of N. hexodon is consumed. The annual economic value is approximately 1,560 million baht. There was an apparent increase in the exploitation rate of N. hexodon from 2011 to 2013, and the amount of N. hexodon reduced sharply from 2014 to 2015 owing to overexploitation for commercial purposes (Fishery Statistics Analysis and Research Group 2017)

Methods

Results

Discussion

Conclusion