Genetic mixed-stock analysis of short mackerel, Rastrelliger brachysoma, catches in the Gulf of Thailand: Evidence of transboundary migration of the commercially important fish
Introduction
Fishery catch primarily consists of individuals from a species (Cooper, 2006). For marine migratory fishes, individuals in a single catch can come from several populations. The populations can also differently contribute to catches. Intensive fishing may simply lead populations to overexploitation and collapse (Allendorf et al., 2008). A clarifying the contribution of each population to mixed-stock fisheries is an important factor for management, conservation and sustainable exploitation of fisheries stocks (Crozier et al., 2004).
Mixed-stock analysis (MSA) is a method to study the population contribution of migratory fishes (Bolker et al., 2007). Various approaches have been employed, for example, otolith shape analysis (Shepard et al., 2010), scale pattern (Tattam et al., 2011), parasite tags (MacKenzie and Abaunza, 1998), physical tags (Reddin et al., 2012), discriminant analysis (Reddin and Friedland, 1999), carbon and oxygen isotope analysis (Fraile et al., 2014) and genetic markers.
A number of genetic markers have been extensively utilized to study the population contribution, for example, mitochondrial DNA (Dunton et al., 2011; Wirgin et al., 2012), single nucleotide polymorphism (Ackerman et al., 2011; Jeffery et al., 2018) and microsatellites (Araujo et al., 2014; Bradbury et al., 2016; Ensing et al., 2013; Kongseng et al., 2020; Östergren et al., 2016; Swatdipong et al., 2013). The genetic markers have an advantage over other markers because all fish individuals are naturally tagged with genetic information since birth (Pella and Milner, 1987). The genetic markers are increasingly recognized as reliable identification and saving time and cost to study the population contribution in mixed-stock fishery. The MSA has been widely applied for determining the population contribution in commercially important fishes, including salmon (Bradbury et al., 2016; Ensing et al., 2013; Flannery et al., 2010), trout (Mäkinen et al., 2015; Östergren et al., 2016; Swatdipong et al., 2013), herring (Bekkevold et al., 2011; Ruzzante et al., 2006), and short mackerel (Kongseng et al., 2020).
Short mackerel (Rastrelliger brachysoma) is one of the most commercially important marine fishes among Gulf of Thailand countries (GoT countries; Cambodia, Viet Nam, Malaysia and Thailand), particularly Thailand. The short mackerel catches from Thai water raised to the total production of 145,300 tons in 2013 (worth 190 M USD). However since 2015, short mackerel catches in Thai water have been continually decreased and the total production was 25,259 tons in 2017 (worth 44 M USD) (Department of Fisheries, 2019). Overexploitation caused by overfishing capacity with a large number of fishing vessels was believed to be the major cause of sharp decline in short mackerel natural resource. This critical event might lead to the short mackerel resource to collapse in near future. To avoid the collapse, appropriate and efficient management must be practiced to conserve the short mackerel resource, especially populations largely contributing to fishery catches.
Being a migratory fish, the short mackerel migrates between feeding and spawning grounds in tropical waters of the central-west Indo-Pacific region (Collette et al., 2011; Collette and Nauen, 1983). From previous studies, large five spawning grounds in Thai water were monitored; outside the Mae Klong River mouth, Samut Songkhram (Mailai-iad et al., 2006), Mu Ko Chang National Park, Trat (Khrueniam and Chareonsombat, 2012; Songchitsawat, 1989; Songkaew et al., 2015), Hua Hin, Prachuap Khiri Khan, Mu Ko Ang Thong National Park, Surat Thani and Pattani (Chalee et al., 2007; Khongchai et al., 2006; Songkaew et al., 2014). Short mackerel populations from the five spawning grounds in Thailand were used as baseline populations for the MSA in GoT. It was found that the Samut Songkhram and Pattani populations dominantly contributed to catches from the Inner and Eastern GoT, respectively (Kongseng et al., 2020). However, the GoT covers waters of Cambodia, Viet Nam, Malaysia and Thailand (GoT countries). Short mackerel populations also display strong migratory behavior. Thus there is a high possibility that short mackerel may migrate far from their spawning grounds and contribute to fishery catches in neighboring countries. Unfortunately, information of short mackerel spawning grounds in Cambodia, Viet Nam and Malaysia has been limited and short mackerel catches from important fishing grounds in the GoT have not been investigated.
The objective of this study was to evaluate the contribution of short mackerel populations from Thai, Cambodian, Vietnamese and Malaysian waters to the fishery catches in the Inner, Eastern, and upper and lower parts of Central GoT. Genetic information and MSA were based on eleven microsatellite loci. Achieved information is envisioned to assist sub-regional collaboration for fishery management of short mackerel in the GoT.
Section snippets
Sample collection and DNA extraction
The baseline populations (larvae and spawning adults of short mackerel; n = 365) in the GoT consisted of the genotype data of five populations (n = 232), taken from Kongseng et al. (2020), and three populations (n = 133), taken from Swatdipong (2019). The last three baseline populations, as mentioned earlier, were collected from Sihanoukville, Koh Kong and Kampot, Cambodia (n = 50), Phu Quoc and Ha Tien, Viet Nam (n = 50) and Tumpat, Malaysia (n = 33) in 2018. Thus, the spawning grounds
Genetic diversity within baseline populations
All eight baseline populations presented highly significant deviation (P < 0.01) from Hardy–Weinberg equilibrium across loci. The FIS varied from 0.080 to 0.213 with average at 0.157. The HO ranged from 0.389 to 0.561 with the average at 0.504; and HE ranged from 0.492 to 0.675 with average at 0.609. The HO was lower than HE in all baseline populations. The AR, based on 21 diploid individual resamplings, ranged from 4.591 to 6.355 with the average at 5.479. The eight baseline populations were
Discussion
The short mackerel populations in the GoT display significant migratory behavior and some populations have a tendency to use transboundary routes. Previous studies of the short mackerel populations in GoT countries, particularly Thailand, were conducted in small water areas. Differently, this study expands the study area to cover all countries surrounding the GoT which is the major habitat of the short mackerel. Baseline populations used for the study of population structure and mixed-stock
CRediT authorship contribution statement
Sirithorn Kongseng: Formal analysis, Investigation, Project administration, Resources, Writing - original draft. Ratanavaree Phoonsawat: Data curation, Funding acquisition, Writing - review & editing. Worawit Wanchana: Data curation, Funding acquisition, Writing - review & editing. Akarapong Swatdipong: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Supervision, Validation, Writing - review & editing.
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgments
We profoundly thank the Department of Fisheries, Thailand and the Southeast Asian Fisheries Development Center (SEAFDEC) for all short mackerel samples with the information of fishing localities. We thank Miss Khwankamon Wongtha and Miss Kanogwat Wansakul to assist the DNA extraction, microsatellite amplification and genotyping of the samples from Cambodia, Viet Nam and Malaysia. Funding of this study was provided under the Biodiversity-Based Economy Development Office (Public Organization),
References (58)
- et al.
Genetic effects of harvest on wild animal populations
Trends Ecol. Evol. (Amst.)
(2008) - et al.
Genetic mixed stock analysis of an interceptory Atlantic salmon fishery in the Northwest Atlantic
Fish. Res.
(2016) - et al.
Range-wide regional assignment of Atlantic salmon (Salmo salar) using genome wide single-nucleotide polymorphisms
Fish. Res.
(2018) - et al.
Individual assignment and mixed-stock analysis of short mackerel (Rastrelliger brachysoma) in the Inner and Eastern Gulf of Thailand: contrast migratory behavior among the fishery stocks
Fish. Res.
(2020) - et al.
Parasites as biological tags for stock discrimination of marine fish: a guide to procedures and methods
Fish. Res.
(1998) - et al.
A history of identification to continent of origin of Atlantic salmon (Salmo salar L.) at West Greenland, 1969–1997
Fish. Res.
(1999) - et al.
Single-Nucleotide Polymorphisms (SNPs) under diversifying selection provide increased accuracy and precision in mixed-stock analyses of sockeye salmon from the Copper river
Alaska. Trans. Am. Fish. Soc.
(2011) - et al.
Advantages and challenges of genetic stock identification in fish stocks with low genetic resolution
Trans. Am. Fish. Soc.
(2014) - et al.
Genetic mixed-stock analysis of Atlantic herring populations in a mixed feeding area
Mar. Ecol. Prog. Ser.
(2011) - et al.
Incorporating multiple mixed stocks in mixed stock analysis: ‘many-to-many’ analyses
Mol. Ecol.
(2007)