Population genetics of cobia (Rachycentron canadum) in the Gulf of Thailand and Andaman Sea: fisheries management implications

Abstract

Population genetics has been recognized as a key component of policy development for fisheries and conservation management and aquaculture development. This study aims to evaluate the genetic diversity and population structure of native cobia (Rachycentron canadum) in the Gulf of Thailand and Andaman Sea, establishing the existing population distributions and contributing information to aid in the development of policy, prior to extensive aquaculture development. Microsatellite analysis of natural cobia populations in these two ocean basins shows similar levels of gene diversity at 0.844 and 0.837, respectively. All populations and almost all microsatellite loci studied show significant heterozygote deficiency. Genetic differentiation between local populations is low and mostly not significant (R ST = -0.0109 to 0.0066). The population shows no marked structure over the long geographic barrier of the Thai-Malay peninsula, either when analyzed using pairwise genetic differences or evaluated without predefined populations using STRUCTURE. Additionally, a Mantel test shows no evidence of isolation by distance between the population samples. The significant heterozygote deficiency at most of the loci studied could be explained by the possibility of null alleles. Alternatively, given the behavior of forming small spawning aggregations, seasonal migration, and hitchhiking on large marine animals, the population genetics could be complex. The population of cobia at each location in Thai waters may be inbred, as a result of breeding between relatives, which would reduce heterozygosity relative to Hardy-Weinberg frequencies, while some of these populations could be making long distance migrations followed by admixture between resident and transient groups. This migration would cause population homogeneity in allele frequencies on a larger geographic scale. The results suggest that 123Aquacult Int (2013( ) 21:197-217 DOI 10.1007 fisheries management for this species should be considered at both national and international levels, and until the possibility of local adaptation is fully investigated, policy development should apply the precautionary principle to ensure the preservation of genetic diversity and the sustainability of local and regional fisheries.

Weak genetic differentiation in cobia, Rachycentron canadum from Indian waters as inferred from mitochondrial DNA ATPase 6 and 8 genes

“…Similar findings were also observed in NJ tree analyses. These results are consistent with assumptions made by Phinchongsakuldit et al (2013) that homogeneity of cobia stocks may range across countries (Myanmar, India, Thailand, Malaysia, Indonesia, Singapore, Cambodia, and Vietnam).…”

“…Moreover, a significant genetic differentiation has been detected in the northern coasts of Persian Gulf and Oman sea by means of microsatellite analysis (Salari et al, 2009). However, there are also reports indicating no marked genetic differentiation over the long geographic barrier in the Gulf of Thailand and Andaman Sea (Phinchongsakuldit et al, 2013). It is important to clarify the population structure of cobia for genetic stock structuring of this species which may help in genetic improvement programmes in near future.…”

Monitoring reveals two genetically distinct brown trout populations remaining in stable sympatry over 20 years in tiny mountain lakes

“…Pritchard et al 2000) and increasingly popular (e.g. Lee et al 2010;Martien et al 2012;Phinchongsakuldit et al 2013).…”

Endocarditis associated with blood fluke infections (Digenea: Aporocotylidae: Psettarium cf. anthicum) among aquacultured cobia (Rachycentron canadum) from Nha Trang Bay, Vietnam

“…Large scale aquaculture production of cobia began in Taiwan in the 1970"s; grow-out from wild-caught fingerlings began in 1993-1995; the first captive reproduction occurred in 1994; and the first mass production commenced in 1997 (Liao et al, 2004;Nhu et al, 2011). At least 23 countries now grow cobia (FAO, 2009;2012;Phinchongsakuldit et al, 2013), with total production increasing from 9 tons in 1997 to >30,000 tons in 2007 (FAO, 2009;2012).…”