Genetic Evaluation of Black Sea Bream (Acanthopagrus schlegelii) Stock Enhancement in the South China Sea Based on Microsatellite DNA Markers

Abstract

This is the first genetic evaluation of hatchery-based stock enhancement of black sea bream (Acanthopagrus schlegelii) in the South China Sea after a two-year monitoring period. In this study, microsatellite DNA markers were used to calculate the contribution rate and analyze genetic changes before and after stock enhancement. Two out of one hundred and sixty nine individuals from three recaptured populations were assigned to broodstock with a contribution rate of 1.18%, revealing that the hatchery-released juvenile fish could survive in the natural environment and had a positive effect on population replenishment in wild black sea bream abundance. However, we found that the release population had the lowest genetic diversity and significant genetic differentiation from other populations. In addition, genetic diversity detected in the recaptured population was lower than that in the wild population, and their genetic differentiation reached a significant level. Our results suggested that releasing cultured black sea bream juveniles with low genetic quality might be genetically harmful for the maintenance of wild genotypes. Therefore, it is necessary to assess the genetic variation of the hatchery population before implementing a stock enhancement and establish a long-term evaluation for monitoring the genetic effect caused by releasing this fish species.

Genetic Structure and Demographic History of Yellow Grouper (Epinephelus awoara) from the Coast of Southeastern Mainland China, Inferred by Mitochondrial, Nuclear and Microsatellite DNA Markers

“…But our results of Hardy-Weinberg equilibrium test is not significant, so we can not confirm the existence of inbreeding or the deficiency of heterozygotes in E. awoara's populations. In some previous studies, we found that marine fish populations off the coast of mainland China generally showed a slight heterozygote deficiency [20,76,77], which might be related to the reduction in effective population size caused by overfishing and the imbalance in the sex ratio [79].…”

“…Microsatellite DNA is an allelic genotype pattern and has a high mutation rate, so it is more suitable for monitoring population structure at present. Our study showed that the average number of alleles (Na) in four populations of E. awoara ranged from 13.4 (BBW) to 20.3 (MB), which was generally higher than that of other marine fishes in the coastal areas of mainland China (Lepturacanthus savala (Na = 10.3~14.0) [75]; Scombridae (Na = 7.455~8.818) [76]; L. polyactis (Na = 10.43~13.71) [20]; Acanthopagrus schlegelii (Na = 5.43~8.00) [77]; Sebastiscus marmoratus (Na = 2~12) [78]), which showed high genetic diversity. We also found that the expected heterozygosity of the four populations was higher than the observed heterozygosity, and the F IS value was positive, showing a deficiency of heterozygotes.…”

The environmental impact and development direction of grass carp, Ctenopharyngodon idella, aquaculture

“…In the fry culture period, 150% of the water was changed, and net drawing and capture were conducted once. Generally, the radius of fry transportation was 500 m (D. S. Li, 1993; J. Li, 2020; J. K. Liu & He, 1992; Wang, 2000).…”

“…To produce 1 kg of grass carp culture, approximately 3 m 3 of water is required, which involves emptying the pond once and emptying ~20%–30% of the pond 6–7 times. The grass carp are fed with green fodder and formula feed was 1:1 (weight ratio), and the feed coefficient of the adult grass carp culture stage was 1.6–1.89 (J. L. Li, 2020; Lin et al, 2006; J. K. Liu & He, 1992; Wang, 2000). The 80:20 modes (i.e., stocking 80% grass carp and 20% bighead carp and silver carp) were used in the adult culture stage (Gui et al, 2019).…”

Microsatellites as Molecular Markers with Applications in Exploitation and Conservation of Aquatic Animal Populations

“…Microsatellite DNA polymorphism evaluation of hatchery-based stock enhancement of black sea bream, Acanthopagrus schlegelii , in the South China Sea revealed the significant genetic differentiation of enhanced populations from native populations and the lower genetic diversity of the recaptured released groups of individuals [ 308 ]. It has been concluded that the release of cultured juveniles with lowered genetic quality is potentially harmful to the conservation of wild genotypes in native populations.…”