• Fisheries and Aquatic Sciences
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• v.11 no.2
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• pp.82-87
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• 2008

Marine fisheries are important natural resources and must be maintained, especially fish species that are important sources of food. Despite the increase in stocking programs to maintain fisheries with artificially raised fish, the genetic impact stocking has on the wild fry population has not been addressed. Genetic variation in rock bream, Oplegnathus fasciatus, within and between wild-caught parents and the $F_1$ generation produced by them in 1 day was assayed using nine highly variable micro satellite markers. The nine micro satellite loci used in this study displayed diverse polymorphisms, and in total, 98 different alleles were observed over all loci. Differences in genetic variability of the $F_1$ offspring compared to their wild-caught parents (brood stock) were observed in terms of allele frequency, gene diversity, and heterozygosity. Although the $F_1$ generation of rock bream was missing 16% of the micro satellite alleles, no significant reduction was found in mean heterozygosity of the $F_1$ population compared to the brood stock. Eight of nine loci showed significant Hardy-Weinberg equilibrium (HWE) deviations in the $F_1$ population, while the brood stock deviated from HWE at three micro satellite loci (KOF85, KOF360 and KOF374). These deviations showed mostly a deficit of heterozygotes. Our results provide evidence for genetic differences in the $F_1$ hatchery offspring compared to their wild-caught parents and reinforce the need for a series of consecutive egg collections to avoid the loss of genetic variability. This also further underscores the importance of monitoring genetic variability of hatchery populations for the conservation of natural rock bream resources.

• Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.16-21
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• 2011

The genetic diversity and population genetic structure of thread-sail filefish, Stephanolepis cirrhifer (Temminck & Schlegel), were examined with a nucleotide sequence analysis of a 495bp fragment of the 5'-end of the cytochrome b gene in 113 fish collected from five populations from the south and east coasts of the Korean Peninsula. Seventeen variable nucleotide sites and 16 haplotypes were defined. The observed haplotypes had a shallow haplotype genealogy and no geographical association. Most of the populations had high haplotype diversity and low nucleotide diversity, and significant negative values for Fu's $F_S$, suggesting rapid, recent population growth from an ancestral population and sudden population expansion. The estimated pairwise fixation indices ($F_{ST}$) indicate that substantial gene flow occurs among these populations. Thread-sail filefish in the South Sea of Korea and East Sea Korean populations forms a single panmictic population. Thus, thread-sail filefish in these areas should be treated as one management unit.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.447-453
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• 2015

We determined the optimal culture conditions for obtaining the maximum number of intestinal bacteria from the olive flounder Paralichthys olivaceus, and studied bacterial diversity using both culture-dependent and culture-independent methods. Using six culture conditions, mean bacterial numbers were greater than $10^6$ per gram of gut mucus, regardless of the medium. However, the bacterial diversity, based on colony morphology, appeared much higher on Marine agar (MA) and Zobell 2216 agar than on other media. We found eight and 17 cultured bacterial phylotypes with 99% minimum similarity in gut mucus grown on MA and tryptic soy agar, respectively. Furthermore, we used genomic DNA extracted from gut mucus to generate 78 random clones, which were grouped into 25 phylotypes. Of these, six were affiliated with Firmicutes, Actinobacteria, and Verrucomicrobia, and were not found using our culture-dependent methods. Consequently, we believe that Marine agar and Zobell 2216 agar are optimal media for culturing diverse intestinal microbes; we also discovered several novel sequences not previously recognized as part of the gut microbiota of olive flounder.

• Journal of Environmental Impact Assessment
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• v.18 no.3
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• pp.151-160
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• 2009

In order to use fundamental data for conservation of species diversity and stream health with dam development, fish investigation in up- and downstream of Pyeonglim Dam was seasonally conducted in 2007~2008. In addition, data of water qualities, investigated for environmental impact assessment, were used to determine a water quality standard level in Pyeonglim Stream, and it revealed that water environment condition was good in the stream. During the study period, a total number of fish caught from the 4 study sites was 5,449 representing 9 families 25 species, and there were 8 Korean endemic species (32.0%) including Rhodeus uyekii, Squalidus gracilis majimae, and Microphysogobio yaluensis. Two species of Zacco temminckii (37.5%) and Zacco platypus (26.3%) were dominant and subdominant in all sites. There were few individuals of the $2^{nd}$-class endangered species (Sand lamprey, Lampetra reissneri) and the introduced species (Bluegill, Lepomis macrochirus), found in the upstream of the dam. and further investigation for conservation of the endangered species and for prevention of the introduced species is needed in future. With fish fauna and multi-metric health assessment model in each sampling attempt, index of biotic integrity(IBI) was evaluated and it resulted mostly in good(26~35) and excellent(36~40) condition in all sites. The results indicate that it is very important to study not only environmental impact assessment with fish composition but also stream health assessment in order to conserve healthy aquatic ecosystem.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.3
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• pp.298-305
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• 2003

Seasonal variation in species composition of fish in the estuary of Saemangeum water in the western coast of Korea was determined using seasonal samples collected by an otter trawl from April 2001 to February 2002. Species compositions did not differ significantly among the 4 stations (p>0.05, Wilcoxon signed-rank test). The cumulative number of species and species diversity (H') approached asymptote after four 30-min trawl hauls. Therefore 30-min trawl samples from each of the four stations were pooled to represent each season. A total of 45 species 2758 individuals and 30,346.8 g of fish were collected during the study period. Of the fish collected Leiognathus nuchalis, Synechogobius hasta, Neosalanx jordani, Konosirus punctatus and Chaeturichthys stigmatias predominated in abundance accounting for $68\%$ of the total number of individuals. Seasonal variation of fish abundance showed a similar trend to those of the other western coastal waters of Korea. The resident species were collected only in spring and autumn. Number of species and biomass were highest in summer due to the catch of many migrating species. In winter catch amount was low, and only 7 species were collected.. Brackish water fishes were more abundant in the study area, and Johnius grypotus and Cynoglossus joyneri were not premominated compared to the other coastal waters. This difference in species compositions may be related to the lower salinity in this estuarine habitat than in the other western coastal waters of Korea.

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.319-327
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• 2015

The present study was carried out to develop biological criteria for aquatic ecosystem health assessment using composition and diversity of collected species. The sampling sites were a total of 67 sites in the Han River (29 sites) and the Nakdong River (38 sites), May and September 2012. During the survey period fish were collected totally 93 species. In each water system, 73 and 61 species were collected in the Han River and the Nakdong River respectively. The current composition of fish species between the Han River and Nakdong River showed similar pattern. The dominant species was Zacco platypus of the Han River, and the Nakdong River was Opsariichthys uncirostris. In particular, ecological characteristics of O. uncirostris frequently appeared in general polluted waters. In conclusion, in the Nakdong River, average value of FAI (Fish Assessment Index) was averaged 41.3, indicating a "poor condition", and the Han River was 53.1, indicating a "poor condition". The aquatic health of the Nakdong River assessed based on FAI was considered to be worse than that of the Han River.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.4
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• pp.288-301
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• 2000

The species composition and seasonal variation of fish assemblage in the coastal water off Gadeok-do, Korea were studied using the monthly trawled samlpes through a year of 1998. During the study period, 110 species of fishes from 57 families were collected. Repomucenus valenciennei, Thryssa kammalensis, Leiognathus nuchalis and Zoarces gilli dominated the fish assemblage throughout the year, and were responsible for $ 57.6{\%}$ and $37.2{\%}$ in the number of individuals and biomass, respectively. Fish species of secondary importance in abundance were Sillago japonica, Apogon lineatus, Pholis fangi, Engraulis japonicus, Thryssa adelae, Pho;is nebulosa, Conger myriaster, Liparis tanakai, Acentrogobius pflaumii, Limanda yokohamae, Chaeturichthys hexanema, Erisphex pottii and Cunoglossus abbreviatus. Higher numbers of species were collected in spring and autumn than in summer and winter. Abundance was high in spring and autumn, and low in summer and winter, Species diversity indices showed that the fish assemblage was more diverse in autumn than any other seasons.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.251-265
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• 2006

To investigate the impingement of fish on the traveling screens, fishes were collected from the traveling screens at Hadong Power Plant through the year of 1999. A total of 84 fish species were collected during the study period. The dominant species were Leiognathus nuchalis, Engraulis japonicus, Trichiurus lepturus and Takifugu niphobles. These four species accounted for 78.2% of the total number of individuals and 52.0% of total biomass collected. The number of fish species, number of individuals, biomass and species diversity indices fluctuated with the seasons. The number of species and biomass were high in April and August, and the number of individuals was high in April and July. However, the number of fish species, number of individuals and biomass of fishes showed low values in winter.

• Korean Journal of Ichthyology
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• v.31 no.3
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• pp.159-164
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• 2019

Species composition and seasonal variation of fish eggs and larvae were investigated from 2017 to 2018. During the study period, the fish eggs were identified as belonging to 6 taxa. The dominant species of fish eggs were Engraulis japonicus, Leiognathus nuchalis, and Konosirus punctatus. These three species accounted for 96% of the total number of individuals collected. The collected larval fishes were identified into 17 taxa, 11 families, and 5 orders. The dominant species of larval fish were Engraulis japonicus, Leiognathus nuchalis, and Konosirus punctatus. These three species accounted for 70% of the total number of individuals collected. The diversity index of the larval fishes was the highest in summer (H'=1.78) and the lowest in winter (H'=1.34). The economically important species in this area were Engraulis japonicus, Konosirus punctatus, Sebastes schlegelii, Cynoglossus joyneri and Stephanolepis cirrhifer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.3
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• pp.243-251
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• 2019

The ichthyoplanktons were sampled by Bongo net to study the distribution of the eggs and larvae in the West coastal waters of Korea during the study period (February, May, August and October of 2017). Collected fish eggs were divided into Engraulis japonicus and unidentified species. The most dominant species, Engraulis japonicus accounted for 79.52% of the total fish egg, which was followed by unidentified species (20.48%). The total of 36 taxa in fish larvae were identified based on morphological and molecular characteristics. Fish larvae were dominant by Gobiidae species. 48.30% of the total catch in abundance, which was followed by Engraulis japonicus (31.86%). These two taxa composed 80.16% of the total collected fish larvae. The seasonal diversity index of species from the collected fish larvae in the West coastal waters in 2017 was 0.625-1.883 and the evenness index was 0.380-0.865. In addition, dominance index was 0.618-0.920 and richness was 0.573-3.189.