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1.
The South Carolina Department of Natural Resources began a stock enhancement research program for red drum, Sciaenops ocellatus, as a possible management strategy for augmenting the availability of juveniles for recreational harvest in South Carolina estuaries. Between 1999 and 2011, approximately 6 million juveniles and 260 million larvae were stocked into the Charleston Harbor (CH) estuary, and proportions of stocked fish were found through standardized sampling as high as 49.6% within a subadult year‐class and up to 12% within the spatially separate spawning population. This study evaluated the genetic influences of stocking on the spawning population, using microsatellite loci, and examined any changes in genetic diversity metrics over the course of the stock enhancement program. Percent contribution of stocked fish among subadult and adult collections was compared against measures of genetic diversity. No statistically significant correlations were found among genetic diversity metrics, suggesting that responsible stocking of red drum as small juveniles has not altered the genetic diversity of adults spawning offshore the CH. Life‐history characteristics likely play a large role in mitigating changes in genetic diversity, despite high contributions of stocked fish in some years, because red drum exhibit a long adult life span and benefit from overlapping generations.  相似文献   

2.
Rock carp Procypris rabaudi is a vulnerable endemic fish in the upper Yangtze River. Hatchery release has been carried out as a major stock enhancement strategy for this species. Ten microsatellite loci were chosen to compare genetic variation between one wild population and two hatchery groups to evaluate the potential impacts of hatchery release on the genetic structure of the wild population. Two different models indicated strong evidence of recent bottlenecks in all groups. The hatchery groups were lower in the mean number of alleles per locus, allelic richness, and allelic diversity compared with the wild population. The 80% membership coefficient indicated that 14% of the wild fish could be assigned as hybrids of wild and hatchery fish. Our results suggested that hatchery release will further reduce the natural genetic diversity in the wild population, change the genetic structure of the rock carp population, and may not benefit restoration of this vulnerable fish species.  相似文献   

3.
In order to provide baseline information for the genetic resources, genetic variation in wild and cultured Pinctada fucata martensii from southern Korea and Japan was studied using nucleotide sequence analysis of 379 base pairs (bp) in the mitochondrial cytochrome oxidase subunit I gene (COI). The study included three hatchery stocks from Korea (Tongyeong) and Japan (Mie and Tsushima) and one wild stock from Korea (Geoje). A total of 3 haplotypes were identified in hatchery stocks of 78 individuals, of which 63 individuals shared 1 haplotype. Overall, nucleotide diversity (π) was low, ranging from 0.000 to 0.002, and haplotype diversity (h) ranged from 0.000 to 0.541. Considerably low haplotype and nucleotide diversities in hatchery stock indicated that low effective population size and consecutive selective breeding of P. fucata martensii could be responsible for the reduction in genetic variation. The wild stock exhibited low haplotype diversity (0.507 ± 0.039) with two shared haplotypes. The results of the present study with first record of wild pearl oyster in Korea support the possibility that the transplanted pearl oyster for overwintering experiments could have survived in winter. In order to enhance and/or maintain genetic diversity in the hatchery stock, further research should be directed toward genetic monitoring and evaluation of the hatchery and wild pearl oysters.  相似文献   

4.
Erosion of the native genetic resources of brown trout in Spain   总被引：2，自引：2，他引：0  
Abstract– We analyzed the introduction of hatchery-reared trout in the Riutort Creek, a small stream in the eastern Spanish Pyrennees. We used gene correlation matrices between individuals to analyze the fish coancestry in the Riutort Creek samples and in the hatchery stock. Hatchery fish disturbed the single ancestry in the native population of the creek, and were clearly detected with principal coordinate analysis of the gene correlation matrix. The amount of introgression produced by successful introductions was estimated from the principal coordinate analysis projections of the matrix of FST values between the putative native Riutort Creek population, the hatchery stock and the introgressed population. In only two years the amount of introgression rose to 10%, indicating that 5% of the native ancestry is lost each year as a result of the stocking program. Based on these results, we review the present understandings on the genetic impact of hatchery fish on indigenous Spanish brown trout populations. The stocking of these populations involves a non-native broodstock widespread through the Spanish hatcheries, but successful stockings appear to be limited to wild populations subjected to occasional releases in protected or unfished areas. Surprisingly, extensive stocking in fished areas result in a more limited genetic impact on the recipient native population.  相似文献   

5.
Supportive breeding of Atlantic salmon (Salmo salar) is commonly employed to maintain numbers of fish where the species has become locally endangered. Increasingly, one of the main aims of population management is the preservation of natural genetic diversity. If the stocks employed in supportive breeding exhibit reduced variation they can alter the natural pattern of genetic variation observed in wild populations. In northern Spain, wild adult salmon are caught every year from local rivers and artificially crossed in order to create supportive stocks. The offspring are hatchery reared until the juvenile stage, then released into the same river where their parents were caught. In the current study, our findings demonstrate that although adult broodstock exhibit a pattern of variation similar to the wild populations, variability at microsatellite loci was drastically reduced in the juveniles released into one of three rivers analyzed. The contribution of broodstock to this juvenile stock was examined by pedigree analysis. A restricted number of females contributing to the hatchery stock was identified as the main cause of loss in genetic variation, possibly due to overmaturity of some multi-sea-winter females. We suggest that better monitoring and control of parental contribution will help in solving the problem of loss of genetic diversity in hatchery populations.  相似文献   

6.
Rainbow trout, Oncorhynchus mykiss (Walbaum), were first introduced into Australia over 100 years ago, and forms the basis of important recreational inland fisheries and an aquaculture industry in south‐eastern Australia. This paper investigates the genetic variation within and between samples of Australian rainbow trout using allozyme electrophoresis. The levels of genetic diversity within Australia do not show marked differences from those observed in hatchery and wild populations from throughout North America, New Zealand and South Africa, but there is evidence for the loss of some rare alleles during translocation from California to Australia via New Zealand. No appreciable difference in genetic diversity was apparent between hatchery and self‐sustaining wild populations of rainbow trout from mainland Australia. However, significant differences in allelic frequencies were observed, with consistent genetic differences between Victorian and New South Wales samples most likely reflecting state‐based hatchery and stocking policies.  相似文献   

7.
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8.
ABSTRACT:   The genetic diversity of wild and hatchery-released Pacific herring Clupea pallasii collected from three brackish lakes and two bays in Honshu and Hokkaido, Japan was examined with five microsatellite loci. All loci showed high genetic variability with expected heterozygosities ranging from 0.815 to 0.945. Significant differences in genotypic and allelic distributions were detected among all locations except for between the two bays in Honshu Island. Pairwise population analysis based on the F ST values showed close genetic relationships among the locations in Hokkaido Island, and the hierarchical analyses of molecular variance showed significant genetic difference between the two islands. Those results suggest the existence of subpopulations due to natal homing. In addition, stocked fish showed as much genetic diversity as the wild fish. The pairwise population analyses also showed close relationships between the hatchery fish and the wild fish in respective stocking areas, showing that no effects of stocking programs on genetic diversity of wild populations were detected.  相似文献   

9.
This research, which is part of a larger study designed to assess the feasibility of winter flounder, Pseudopleuronectes americanus, stock enhancement in New Hampshire, identifies hatchery feeds that optimize feeding‐related performance of fish once released in the wild. Fish reared on post‐nauplii of brine shrimp, Artemia sp., white worms, Enchytraeus albidus, common burrower amphipods, Leptocheirus plumulosus, and formulated pellets were evaluated post‐release from in situ cages using survival, growth rate, feeding onset and incidence, stomach fullness, diet composition, and nucleic acid‐based condition as indicators of hatchery diet suitability. Amphipod‐reared fish had the highest mean stomach content index of all feed types, including wild fish. Wild and worm‐reared fish exhibited the most similar survival, overall stomach fullness, and diet composition profiles over time. Amphipod‐reared fish ranked highest in overall performance; however, if wild fish performance is viewed as the ideal for a stocked fish, worm‐reared fish performed optimally. This study describes hatchery feeding strategies that may ease the transition of flatfish released into the wild for stock enhancement.  相似文献   

10.
Stocking is an important management tool for enhancing fisheries resources, but its actual contribution to fisheries resources is controversial, taking into consideration both the positive and negative effects. This study compared density and biomass of hatchery (otolith thermal marked) and wild masu salmon parr between stocked and unstocked rivers to evaluate the contribution of stocking with hatchery‐reared fish. Density and biomass of all fish did not differ between stocked and unstocked rivers. Moreover, density and biomass of wild fish in the stocked rivers were lower than those of the unstocked rivers. Density and biomass of hatchery fish in a non‐natural reproducing river were similar with those of all fish in natural reproducing rivers. These results indicate that hatchery stocking does not have positive effects on population density or biomass but replaces wild fish with hatchery fish and that non‐natural reproducing areas are more suitable as stocking sites.  相似文献   

11.
The Japanese flounder Paralichthys olivaceus is a commercially important fish that is stocked extensively from hatchery rearing programs in Japan. To examine the genetic variability of hatchery-raised juveniles of the Japanese flounder that are used for stocking into natural waters, we analyzed a portion of the mitochondrial genome. The mtDNA region extending from the 3'half of the cytochrome b gene to the central domain of the control region was PCR amplified and analyzed using 11 restriction endonucleases. We identified 34 polymorphic cleavage sites out of a total of 61 sites, which resulted in 67 different haplotypes in a total of 265 offspring, examined from eight hatchery stocks. Haplotype diversity of offspring at each of the eight hatcheries ranged from 0.49 ± 0.09 (SE) to 0.94 ± 0.03 (SE). Also, we observed 40 polymorphic sites out of a total of 59 sites, which resulted in a total of 50 haplotypes in 60 wild flounder. Haplotype diversity of the wild population was 0.98 ± 0.01 (SE). The use of subcultured fishes as broodstock appears to be one of the most important causes of reduced genetic diversity in hatchery-raised flounder juvenile. Our results suggest that the use of wild fish for broodstock is an effective way to maintain genetic variability in Japanese flounder offspring.  相似文献   

12.
Gillnets fished in North Carolina, USA, estuaries have high rates of bycatch relative to the target catch of southern flounder, Paralichthys lethostigma Jordan & Gilbert. This study tested whether rectangular‐mesh gillnets would maintain catch rates of southern flounder and reduce fish bycatch relative to conventional diamond‐mesh gillnets in two North Carolina estuaries. In the Neuse River estuary, catch rates of legal southern flounder were not different between the two mesh shapes, but the bycatch of red drum, Sciaenops ocellatus (Linnaeus) and other fish species was reduced with rectangular‐mesh net. In the Newport River estuary, southern flounder and red drum catches were reduced in rectangular‐mesh net, but the decrease was greater for red drum. Catches of sublegal southern flounder were reduced in the rectangular‐mesh net in both estuaries. Reduced catch rates of sublegal southern flounder and bycatch species suggest rectangular mesh may help manage stocks of estuarine fish species in areas where gillnets are used to target flatfishes.  相似文献   

13.
Sea trout, Salmo trutta L., populations in the Slupia River basin have been affected by mass stocking with smolts and fry. This work is focused on a small‐scale differentiation in sea trout populations from one basin with a strong emphasis on the relationship between wild and hatchery origin fish. A total of 216 sea trout were genotyped at 10 microsatellite loci. Global FST obtained by amova was low at 0.0165. Pairwise FST were significant for all tests except wild and stocked adults. The highest pairwise difference was found between the hatchery sample and Kwacza (FST = 0.038). Analysis of the genetic structure revealed micro‐geographical differentiation with four subpopulations. The quality of the artificial spawning was found not to be adequate with a high risk of adverse effects to the whole population. All future stocking actions in the basin should consider the existing population structures.  相似文献   

14.
An increasing demand for stocking of hatchery-reared ayu, Plecoglossus altivelis, has aroused concerns about their genetic status which has an effect on their post-stocking performance and the conservation of native biodiversity. Instead of costly analysis, fluctuating asymmetry (FA) was examined to test its suitability as an indirect measure of genetic diversity. Two bilateral traits, pectoral and pelvic fin rays, were targeted, and two wild and four hatchery populations of ayu were sampled for comparison. Frequency of FA in soft-rays was not similar between specimens in both pelvic and pectoral fins. The wild populations did not show FA incidences lower than the hatchery populations, suggesting a considerable degree of environmental stress operating in the wild populations. Comparison between the hatchery populations showed overall increasing FA incidence with the decrease in genetic diversity, although the correlation was not complete in detail. In conclusion, FA can be used as a convenient tool to compare genetic status, but quantified evaluation is rather limited to monitoring changes in the genetic variation within a hatchery population.  相似文献   

15.
Hatchery release is one of the most popular management tools in fisheries, forestry and wild life management, while its negative impacts on wild populations are a global concern. Research and monitoring of its impacts are generally lacking, and the usefulness of hatchery release for fisheries and conservation objectives is unclear. Here, I evaluated positive and negative impacts of worldwide marine stock enhancement and sea ranching programmes in a systematic review associated with meta‐analyses with the goal of reducing bias of the review. Vast numbers of individuals of more than 180 species are released into the wild each year, but most studies are at experimental stages to assess its potential, and empirical studies are sparse for evaluating the impact on fishery production. Most cases are economically unprofitable except for a few successful cases or unevaluated. The effects of releasing juveniles can be dwarfed by the magnitude of natural recruitment when the spawning stock produces much larger recruitment than released juveniles. Density‐dependent growth caused by competition of food can be substantial, and growth rates of hatchery and wild fish and other competitive species can simultaneously be reduced when stocking exceeded the carrying capacity. Relative reproductive success can vary depending on the species, seed quality and environmental factors. Empirical studies show evidence of substantial gene flow from hatcheries, but fitness reduction in stocked populations has not been reported. The results represent the current state of worldwide marine stock enhancement and sea ranching activity and provide key information for growing fields of artificial propagation and conservation.  相似文献   

16.
Genetic discrimination using DNA fingerprinting is rapidly developing for cultured stock and wild fish populations. Microsatellites and AFLPs are being widely used in aquaculture to assign fish or processed fish products, to their claimed origin, paternity or strain. In the present study, 147 AFLP and 4 microsatellite markers were used as genetic tags in gilthead seabream, Sparus auratus. Specimens from two different hatchery broodstocks (one of Atlantic and one of Mediterranean origin) and wild fishes from a natural population were fingerprinted. Putative offspring from these broodstocks were computer-generated, and the confidence in the parentage assignment of their genetic profiles to the hatchery broodstock assessed. The virtual offspring were then mixed with specimens from a natural population to simulate an accidental escape from a floating cage. The risk of false paternity inclusion was evaluated to test the ability to identify either Atlantic or Mediterranean hatchery offspring among wild fish. The method proved to be reliable, and could therefore be used to forecast the impact of fish farm escapees.  相似文献   

17.
The level of genetic diversity in a cultured Atlantic salmon (Salmo salar) population from Tasmania, Australia was examined at 11 microsatellite loci and compared with that in its progenitor population from the River Philip in Nova Scotia, Canada. The reference progenitor population consisted of archived scales collected from wild River Philip salmon in 1971 and 1972, not long after salmon from this river were imported into Australia in the mid‐1960s. The Tasmanian hatchery stock had a significant reduction in the mean number of alleles (31–43%) and mean allelic richness (28–39%) across all microsatellite loci compared with the wild Canadian population. Mean heterozygosity levels remained unchanged. Estimates of per‐generation effective population sizes for the Tasmanian population, based on allele frequency temporal variance with the wild progenitor population, ranged from 102–207 individuals and reflected hatchery records.  相似文献   

18.
Abstract To preserve the local genetic patrimony of wild aquatic species, population enhancement should be limited to supportive breeding of native lineages and controlled releases in target areas with depleted population size. This is the case of brown trout, Salmo trutta L., in northern Iberia, a species of high economic and cultural value in the region. Employing a combination of conserved and hypervariable genetic markers, illegal stocking of domestic brown trout in protected areas (National Park, Natural Reserve) within the Cantabric chain was detected. The most likely origin of the domestic individuals was determined by assignment tests to hatchery stocks as a result of past releases conducted downstream and out of the protected areas. Where connectivity exists along a water course, the entire drainage should be considered as a single management unit to preserve the native genetic diversity of upstream protected areas.  相似文献   

19.
Abstract – Investigating the influence of evolutionary forces on the genetic structure and genetic diversity remains a major challenge. Yet, it is of considerable interest for conservation and management of a species. This study investigates the influence of life‐history and landscape features, such as altitude, connectivity and habitat size, on genetic diversity and genetic structure of brown trout (Salmo trutta L.) with stream‐resident, lake‐dwelling and sea‐migrating life‐history in two river systems in northern Sweden. Using regression tree analysis including ecological and landscape characteristics, we show that life history is the most important variable explaining genetic diversity and population differentiation. Sea‐migrating populations show high diversity and low differentiation, and lake‐ and stream‐resident populations show low diversity and high population differentiation, among all samples. No overall genetic correlation with geographical distance was noted; however, among sea‐migrating populations within the River Vindelälven drainage, this pattern was observed. This study illustrates that life‐history and landscape features help to explain genetic structure and genetic variation. The information is important for conservation and management actions, such as fisheries regulations, habitat restorations, stocking of hatchery fish, defining management units and introducing genetic monitoring programmes.  相似文献   

20.
Abstract Stocking has had a considerable effect on wild brown trout, Salmo trutta L., populations throughout Europe. To elucidate this impact and to outline further management strategies, the genetic structure of 25 wild populations and five hatchery stocks from Czech Republic and Slovakia were analysed using mitochondrial (control region) and nuclear DNA (microsatellites, LDH‐C1*) markers. Stocking practices have caused massive hybridisation between the Atlantic and Danube brown trout strains in the central Danube basin and have lead to a loss of among‐population divergence in Slovakia and the eastern part of Czech Republic. Comparison with studies from neighbouring countries revealed substantial differences in haplotype, allele frequencies and genetic diversity across Central Europe. Differences in stocking management and origin of breeding stocks appear to be crucial factors for the spatial variability of the genetic structure of brown trout.  相似文献   

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