Resource Status and Effect of Long-Term Stock Enhancement of Large Yellow Croaker in China

Abstract

The large yellow croaker, Larimichthys crocea, was once the most abundant and economically important marine fish in China. Thus far, it has also been the most successful mariculture fish species in China. However, its wild stock severely declined in the 1970s because of overexploitation, and therefore hatchery release has been carried out for stock enhancement since 2000. As a migratory fish, large yellow croaker was divided into three geographical stocks according to ambiguous morphological and biological characteristics in early documents. To investigate the identity of wild large yellow croaker populations and assess the influence of hatchery supplementation on wild populations, a total of 2,785 cultured individuals and 591 wild individuals were collected from 91 hatcheries and six wild populations along the coast of mainland China and analyzed using two mitochondrial genes [cytochrome oxidase I (COI) and cytochrome b (Cyt b)] and one nuclear gene (RyR3). The higher haplotype diversity and moderate nucleotide diversity of wild large yellow croaker indicated that overexploitation, which caused a sharp decrease in biomass, did not lead to a loss of genetic diversity. According to phylogenetic construction and network analysis, the absence of a significant population structure pattern revealed a single panmictic population of wild large yellow croaker with exception of a population collected from the Sansha Bay, which showed high genetic relatedness to the cultured population, suggesting significant genetic effects resulting from stock enhancement. Overall, our study suggests no genetic differentiation in the entire wild population of large yellow croaker, which means that we have great flexibility in mixing and matching farmed and wild populations. However, since the result showed that domestication, the relaxation of purifying selection, increased genetic loads, and maladapted farmed fish will be at a selective disadvantage when cultured juveniles are released in the wild, the effectiveness of stock enhancement and the negative impact of hatchery-wild fish hybridization on the wild population must be carefully evaluated in future.

Temporal Genetic Stability Despite Decades of Overexploitation for Large Yellow Croaker in the East China Sea

“…The results suggested that neither genetic drift nor gene flow from allopatric populations had strongly altered the genetic composition of stocks in the East China Sea over this time-span. Consistent with our results, a recent genetic study with three molecular markers also detected relatively high genetic diversity in wild populations of large yellow croaker, which was comparable to those of othermarine fishes (Yuan et al, 2021). Our result was also consistent with previous results of temporal genetic analysis in Atlantic salmon, Brown trout, North Sea sole and Copper redhorse, which also documented temporal stability of genetic diversity over decades of overexploitation (Hansen et al, 2002;Lippe et al, 2006;Cuveliers et al, 2011;Pinsky et al, 2021).…”

“…Sporadic genetic differentiation among temporal samples might occur due to random genetic drift or technical errors. To a large extent, these results were in accordance with previous studies on populaiton genetic structure of large yellow croaker in which a single panmictic population were suggested across its distribution (Han et al, 2015;Yuan et al, 2021). Our results indicated that the population genetic structure of large yellow croaker was generally spatio-temporal stable and had not been changed substantially due to the fishing pressure.…”

“…Benefiting from success of artificial mariculture since 1985, stock enhancement of large yellow croaker by release of artificial seedlings was extensively conducted in the East China Sea (Wang et al, 2013). Stock enhancement has been one of the conventional strategies for stock recovery and management of large yellow croaker (Yuan et al, 2021). However, previous studies have shown that the ecological and genetic effects of hatchery releases are of real concern because of the potential in facilitating inbreeding depression and reducing the fitness of wild stocks (Grant et al, 2017), such as Atlantic salmon (Hagen et al, 2020), Salvelinus fontinalis (Marie et al, 2010), and Acanthopagrus schlegelii (Shan et al, 2020).…”

Declining Population Sizes and Loss of Genetic Diversity in Commercial Fishes: A Simple Method for a First Diagnostic

“…We selected ten fish species with accumulated sample sizes larger than 30 individuals as representatives of the most abundant fish in Sansha Bay (Supplementary Table S1). One of the species, Larimichthys crocea, is not representative of wild populations but farmed resulting from long-term (since 2002), restocking activities in Sansha Bay after the natural populations were depleted in the 1980s (Liu and Sadovy de Mitcheson, 2008;Liu et al, 2020;Yuan et al, 2021), and it was taken as a negative control (i.e. expected low genetic diversity) in the evaluation of the other fish species.…”

A Study on the Effects of Calcium Lactate on the Gelling Properties of Large Yellow Croaker (Pseudosciaena crocea) Surimi by Low-Field Nuclear Magnetic Resonance and Raman Spectroscopy

“…It is rich in protein and fat as well as essential amino acids and polyunsaturated fatty acids. Large yellow croaker resources are very abundant in China [ 2 ]. In 2020, the seawater aquaculture production of the large yellow croakers had reached 21,353,100 tons in China.…”