Genetic Assessment of a Black Rockfish, Sebastes schlegelii, Stock Enhancement Program in Lidao Bay, China Based on Mitochondrial and Nuclear DNA Analysis

Abstract

The black rockfish Sebastes schlegelii is a commercially important fish species for marine fishery stock enhancement in Asia. This work aimed to evaluate the potential genetic impacts of releasing hatchery-reared juvenile black rockfish on wild stock in Lidao Bay, China. A partial sequence of the mitochondrial DNA (mtDNA) control region and 38 microsatellite DNA loci were used to assess the genetic impact. The haplotype diversity parameter (h) and nucleotide diversity parameter (π) in hatcheryreleased stock were 0.902 and 0.00483, respectively. The h values in wild stock before stock enhancement and the mixed stock after enhancement were 0.970 and 0.939 (p = 0.025), respectively, and the π values were 0.00581 and 0.00526 (p = 0.150), respectively. The mean effective number of alleles (Ae) in hatchery-released stock was 4.76, the mean polymorphism information content (PIC) was 0.674, the observed heterozygosity (Ho) was 0.668, and the expected heterozygosity (He) was 0.697. In wild stock before stock enhancement and the mixed stock after enhancement, the Ae, PIC, Ho, and He values were 6.01 and 5.82, 0.698 and 0.716, 0.709 and 0.741, and 0.735 and 0.754, respectively. These results indicated no marked decrease in the hatchery-released stock, although it displayed slightly lower levels of genetic diversity and heterozygosity than the wild stock. And the mixed stock after release exhibited similar genetic diversity to that of the wild stock before release. Accordingly, we propose that stock enhancement may not cause genetic diversity reduction on wild S. schlegelii stock in Lidao Bay over the short term. Whereas, discriminant analysis of principal components (DAPC) analysis identified three major clusters. The fixation index (F ST) and analysis of molecular variance (AMOVA) also clearly showed low level but significant differentiations between the hatchery-released and wild stocks, and the wild stock before enhancement and the mixed stock after enhancement. Consequently, long-term genetic evaluation might be required.

Genetic Stock Identification and Adaptability of Hatchery-Reared Black Rockfish, Sebastes schlegelii, Released Into the North Yellow Sea waters

“…We observed that the S. schlegelii population showed relatively high genetic diversities before and after stock enhancement. Similar results have been reported in the Shandong peninsula, China (Wang et al, 2020). There was no significant difference in Na, Ne-allele and Ho between different stocks but the hatcheryreared stock, RA2019, exhibited a significantly lower Ar value than NA2019, after sequential Bonferroni correction (P < 0.05).…”

“…However, little research had evaluated the impacts on wild S. schlegelii populations. We only found that Wang et al (2020) reported that no marked decrease in the hatchery-released stock, low but significant differentiation between the hatchery-released and wild stocks, as well as the wild stock before enhancement and the mixed stock after enhancement in Lidao bay, Shandong peninsula. Aside from the above enhancement events, there has been no release of S. schlegelii in the Liaodong peninsula before 2019.…”

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

“…In addition to directly increasing the biomass of wild fish stocks, stock enhancement helps local stocks to maintain self-sustainable development [3]. Stock enhancement programs have been widely applied for decades over 300 species, such as flathead grey mullet (Mugil cephalus), silver carp (Hypophthalmichthys molitrix) and Korean rockfish (Sebastes schlegelii) [4][5][6][7]. In China, about 95 billion individuals composed of marine fish, shrimp and scallops were released into coastal regions during 2004-2013 [7].…”

“…Stock enhancement programs have been widely applied for decades over 300 species, such as flathead grey mullet (Mugil cephalus), silver carp (Hypophthalmichthys molitrix) and Korean rockfish (Sebastes schlegelii) [4][5][6][7]. In China, about 95 billion individuals composed of marine fish, shrimp and scallops were released into coastal regions during 2004-2013 [7]. Nevertheless, negative genetic effects of hatchery-released juveniles on natural populations have been reported in some fish species.…”

Southward range extension of the goldeye rockfish, Sebastes thompsoni (Actinopterygii: Scorpaeniformes: Scorpaenidae), to northern Taiwan

“…Members of Sebastes generally occur in cold-temperate and boreal waters (Wourms 1991;Mecklenburg et al 2002;Hyde and Vetter 2007), except for four species residing in the North Atlantic and two species being found in the Southern Hemisphere (Chen 1971;Rocha-Olivares et al 1999;Garabana 2005;Hyde and Vetter 2007). In addition, rockfishes are economically important species, especially in temperate regions (Muto et al 2018;Wang et al 2020). The distributions of rockfishes in the Northern Hemisphere are generally present from northern Japan and the waters of Alaska to California (Robins et al 1980;Wourms 1991).…”