Spatial Genetic Structure and Diversity of Large Yellow Croaker (Larimichthys crocea) from the Southern Yellow Sea and North-Central East China Sea: Implications for Conservation and Stock Enhancement

As a wild resource, the large yellow croaker Larimichthys crocea has been seriously threatened since the mid-1980s. Owing to the implementation of protection measures, such as the establishment of a protection zone, fishing prohibitions, restocking programs and successful mariculture, its resources have gradually recovered year by year. Limited by the low spatial resolution and incomplete spatial coverage of sampling stations, the spatial genetic structure and diversity of large yellow croakers from the southern Yellow Sea and north-central East China Sea remains unclear. In order to evaluate the genetic diversity status of this wild stock, 22 wild sites were collected from the southern Yellow Sea and north-central East China Sea and analyzed by investigating genetic variability and its population structure using mitochondrial COI sequence in this study. Among the 662 sequences, a total of 71 different haplotypes were defined. The haplotype diversity (h) and nucleotide diversity (pi) values were 0.644 similar to 1.000 and 0.00220 similar to 0.00473 respectively. The highest h and pi occurred in the southern Yellow Sea (YS). AMOVA analysis showed no genetic differentiation among those 22 sites after Bonferroni correction. By comparing with previous studies, the croaker has maintained relatively steady genetic diversity in recent years. Our result also suggested that the croakers in the South Yellow Sea and north-central East China Sea belonged to the same group. Thus, they can be released as a management unit without regard for heterogenicity among those in the sea area. The YS populations can serve as parents for released fish fries in the South Yellow Sea and north-central East China Sea.