Geographic variations of the mottled skate, Beringraja pulchra (Liu, 1932) (Rajidae) in the Yellow and East seas based on molecular and morphometric data

Abstract

In order to prove the fisheries-related hypothesis of the presence of two local populations of the mottled skate, Beringraja pulchra in the Yellow Sea (Sensu Jo et al., 2011), the geographic variations of 90 individuals (in molecule) and 129 individuals (in morphology) were investigated. The skates were collected from the middle Yellow Sea (Daechungdo), southern Yellow Sea (Heuksando), and the middle East Sea (Ulleungdo) using gill nets, bottom trawls and longlines. Comparing 471 base pairs of mitochondrial DNA cytochrome c oxidase subunit I (mtDNA COI) sequences, only three haplotypes (BR1-BR3) were found. The Daechungdo and Heuksando individuals displayed all three haplotypes, whereas the Ulleungdo individuals displayed a single haplotype (BR3). Pairwise fixation indices (FST) showed that the Daechungdo and Heuksando individuals were not genetically distinguishable (with a value of −0.0344), whereas the Ulleungdo individuals were clearly distinct from both the Daechungdo and Heuksando individuals (with values of 0.6875 and 0.6871, respectively). Similar to the molecular result, a canonical discriminant analysis based on seven morphometric characters showed that the Ulleungdo individuals had positive values on the first axis, whereas those from the other two locations had negative values, slightly differentiating the two populations (East Sea population vs Yellow Sea population). This study is the first to identify two populations of mottled skate in the northwest Pacific.

Upwelling and eddies affect connectivity among local populations of the goldeye rockfish, Sebastes thompsoni (Pisces, Scorpaenoidei)

“…Previous study in the Japanese Archipelago, which was performed preliminarily for 10 individuals in only two regions (East Sea and Pacific coast), respectively, suggest that genetic population structure is likely a single panmictic group like this study, but showed a higher genetic diversity (overall h = 1.0000, π = 0.0345) rather than Korean S. thompsoni (overall h = 0.9998, π = 0.0231; Higuchi & Kato, 2002). This would suggest that stable population levels and extensive gene flow in Japan have fostered the generation and persistence of very high genetic diversity (Grant & Bowen, 1998 Im, Jo, Ji, Myoung, & Kim, 2017). Therefore, during a period of frequent glacial-interglacial cycles, Korean S. thompsoni might have undergone repetitive recolonization events, with the segregation of the southern Korean population in refugia and local extinction of the East Sea population.…”

Population structure of the ocellate spot skate (Okamejei kenojei) inferred from variations in mitochondrial DNA (mtDNA) sequences and from morphological characters of regional populations

“…7) also almost corresponded with the results from the mtCR analysis; our results supported the uniqueness of the regional populations and suggested limits to migration. Such fine-scale population structures in other skate species have already been well documented (e.g., Chevolot et al, 2006;Griffiths et al, 2010Griffiths et al, , 2011Dudgeon et al, 2012;Im et al, 2017;Vargas-Caro et al, 2017) and are considered to have been derived from the constraints of low dispersal because of large benthic egg capsules and the absence of a pelagic larval stage. Vargas-Caro et al (2017) suggested that smaller skates inhabiting coastal areas had well-defined population structures than larger skates inhabiting offshore areas because body size and habitat are related to dispersal potential.…”

“…However, despite the potential population structuring and high economic value of O. kenojei, there have been no studies of genetic structure at the population level for this species-information that is crucial for fisheries management and conservation practices. In some skate species, molecular genetic studies have revealed both population structure and demographic history, as well as the existence of cryptic species based on mitochondrial DNA (mtDNA) sequences (e.g., Valsecchi et al, 2005;Chevolot et al, 2006;Griffiths et al, 2010;Griffiths et al, 2011;Spies et al, 2011;Dudgeon et al, 2012;Frodella et al, 2016;Im et al, 2017;Vargas-Caro et al, 2017). The mtDNA control region (mtCR) has been frequently used to infer population structures within species because of the high levels of nucleotide polymorphism evident in several skate species (Valsecchi et al, 2005).…”

Fifty years of tagging skates (Rajidae): using mark-recapture data to evaluate stock units

“…Identifying biologically discrete fish stocks can be problematic, and holistic and multidisciplinary approaches to provide more accurate definitions of stock structure are especially challenging (Pawson & Jennings, 1996; Begg & Waldman, 1999). Consequently, few multidisciplinary studies have applied a range of approaches to inform on stock units of marine fish (Abaunza et al ., 2008; Im et al ., 2017). Many studies on stock units have been focused on individual methods, such as species distribution and relative abundance (Pawson & Ellis, 2005), molecular genetics (Carvalho & Hauser, 1994), morphometric discrimination (Cadrin, 2000), life-history parameters (Begg et al ., 1999), parasites (McVicar, 1977; Lester, 1990; MacKenzie & Abaunza, 1998; Irigoitia et al ., 2017), contaminant and microchemistry analysis (Campana et al ., 2000) and tagging experiments (Walker et al ., 1997).…”