• Journal of Photoscience
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• v.9 no.2
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• pp.269-271
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• 2002

To investigate the visual and extra-ocular photoreception, we cloned the opsin genes in ayu (Plecoglossus allivelis). Amplified fragments encoding exon-4 (-5) of opsin cDNAs were cloned from the retina and brains of ayu, and sequenced. One clone was identified as rod (AYU-Rh), two as green cone (AYU-GI, -G2), one as red cone (A YU-R), two as ultraviolet cone (AYU-UVl, UV2), one as VA (AYU-VA), and one as extra-ocular rod (AYU-ExoRh) opsins. 335 amino acids sequence deduced from the full-length cDNA of AYU-Rh showed high identity with that of other fish. Southern blotting analysis indicated that ayu possess two 'rhodopsin' genes, one is visual rhodopsin and the other is non-visual extra-ocular rhodopsin. In situ hybridization showed that the mRNA of AYU-Rh was localized only in rod cells in the retina. On the other hands, AYU-ExoRh was expressed only in the pineal. We cloned two isoforms (AYU-VAM and -VAL) of VA opsin from ayu. The deduced amino acid sequences of these variants were identical to each other within the first 342 residues, but they showed divergence in the C-terminal sequence. AYU- VAL corresponded to the long isoform found in other fish, and AYU-VAM was identified as a new type of VA opsin variant. Pal-VAM is a new probably functional non-visual photoreceptive molecule in fish.

• Journal of Aquaculture
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• v.12 no.2
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• pp.123-135
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• 1999

In order to investigate the effect of salinity on growth and osmoregulation of the sweetfish, Plecoglossus altivelis, the fish (post-larva, juvenile, adult) reared in seawater were directly transferred into the experimental rearing water of the different salinities (post-larva : $0\textperthousand$, $5\textperthousand$, $10\textperthousand$, $15\textperthousand$, $20\textperthousand$, $30\textperthousand$. juvenile : $0\textperthousand$, $\10textperthousand$, $20\textperthousand$, $30\textperthousand$. adult : $0\textperthousand$, $15\textperthousand$, $35\textperthousand$, respectively). Fish samples were taken in time courses after transfer for blood and body fluid collection. The changes of sodium, potassium concentration and osmolality of the body fluid and plasma, muscle water content, gonadosomatic index (GSI) and hepatosomatic index (HSI) in the experimental fish were observed in time courses. Growth rate of the post-larva in $\5~25\textperthousand$ were faster than in $0\textperthousand$ (P<0.05). Survival rate was very low in $0\textperthousand$ (P<0.05). No fish survived more than 50 days after transferred into $0\textperthousand$. The concentration of sodium, potassium and osmolality in body fluid of the juvenile sweetfish were slightly decreased at 0.25 day after the beginning of the maintainable level of sodium, potassium and osmolality were $36.4\pm6.2 mM/\ell, 47.5\pm0.7 mM/\ell, 366.3\pm19.1 mOsm/kg, respectively. Except potassium concetration, fish in $0\textperthousand$ and $10\textperthousand$ displayed the pattern of hypoosmotic regulation. Growth rate and survival rate of juveniles of $30\textperthousand$ are significantly low than other groups (P＜0.05). The concentration of sodium, potassium and osmolality in plasma of adult sweetfish were slightly decreased at 1 day after the beginning of the maintainable level of sodium, potassium and osmolality were $159.0\pm2.5 mM/\ell, 5.8\pm0.9 mM/\ell, 338.1$\pm13.3 mOsm/kg respectively. Compared with these values, fish in $0\textperthousand$ and $15\textperthousand$ displayed hypoosmotic regultion. Growth and survival rate of adult in $35\textperthousand$ are significantly low than other experimental groups. GSI was the highest in $15\textperthousand$ after 60 days. HSI was the lowest in $35\textperthousand$. With decreased salinities, oxygen consumption was found to be decreased in the other experimental groups compared to the more than $30\textperthousand$.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.32-40
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• 2006

The Ichthyofauna and fish community were studied in the lower course of Imjin River from April 2003 to October 2004. During the survey period 80 species belonging to 23 families were collected. Twenty-five species (31.1%) of them were Korean endemic species. Exotic fishes were Carassius cuvieri, Lepomis macrochirus and Micropterus salmoides, and they complied 1.3% of total catch. The species of Hemibarbus mylodon was identified as natural monument, and acheilognathus signifer, Pseudopungtungia tenuicorpa, Gobiobotia macrocephala and Gobiobotia brevibarba were endangered species. Migration fish were Coilia ectens, Anguilla japonica, Plecoglossus altivelis and Takifugu obscurus. Dominant species were Zacco platypus (St. 1), Microphysogobio yaluensis (St. 2), Hemibarbus labeo (St. 3, 4) and coilia ectens (St. 5). The lower course of Imjin River was more abundance of species, high diversity and richness, and lower dominance index than those of the lower course of Han River.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.4
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• pp.228-232
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• 1970

From the standpoint of fishery science it is an interesting matter to note that the size of Plecoglessus altivelis population on Cheju Island is smaller than that of the Nakdong River located in the southern part of Korea's mainland. Therefore the author carried out a comparative analysis to determine whether the populations differ because of racial or because of environmental conditions. The morphometric characters of the head length and the body length were used for the analysis of covariance and computed by a standard regression method of testing for the homogeneity of the populations. All samples were collected during 1968 and 1969 in the Milyang Stream of the Nakdong River and the Cheonji Stream of Cheju Island. The results of the analysis of the populations based on the significance test are as follows: 1. Since the F value observed was only 1.023 ($n_1=1,\;n_2=42$) the conclusion was reached that the samples could both belong to the same population. 2. In comparison with the deviations of the regression coefficients between the fish of the Nakdong River and Cherinji Stream, the populations were also highly significant suggesting that thelr belong to the same population. 3. The conclusion is that the fish of Cheju Island became a smaller fish in size due to an environmental condition but not due to racial characteristics.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.319-321
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• 2001

Supply of ntrition-balanced feed is very important for growth of fish, especially for growth of early period of fish. Therefore, most of commercial feeds for larval and juvenile fish are relatively expensive due to high level of the several nutrients to satisfy their requirements for growth. Overfeeding larval fish may increase fish production cost because of larvae feeds high price and deteriorate water quality, eventually reduce growth of fish. (omitted)

• Development and Reproduction
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• v.4 no.1
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• pp.79-85
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• 2000

This study was made to optimize the conditions needed to produce two types of gynogenetic diploids in the sweet fish, Plecoglossus altivelis. Firstly, ultraviolet (UV) ray doses between 3,000 erg to 14,000 erg/$\textrm{mm}^2$ were tested to inactivate sperm genetically. Based on the appearance of the haploid syndromes in the embryo, a dose of UV ray 6000~7000 erg was required to inactivate sperm genetically. Then, cold shock treatment at 1~2$^{\circ}C$ for 15~30 min were conducted to retain the 2nd polar body in inseminated egg. The best elapsed time before the start of the cold shock was examined between 5~8 min. The experiments in which began 5 min after insemination at 1~2$^{\circ}C$ during 17.5 min gave 21.2％ survival rate and 89.7% normal eyed embryo rate. The gynogenetic diploid produced by suppression of the first cleavage, a considerably high number of heteroploids appeared and high mortality was observed at the metamorphosis stage, so further investigation is needed. The production of gynogenetic diploids were confirmed by GPI isozyme marker. The heterozygous type in Gpi-1 locus was observed in the meiotic-G2N as a result of gene-centromere recombination during meiosis. The heterozygous type was never observed in mitotic-G2N and showed segregation into two homozygous types at Gpi-1 locus.

• Development and Reproduction
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• v.4 no.2
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• pp.147-152
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• 2000

Four clonal lines of ayu, Plecoglossus altivelis, were produced through gynogenesis, mixed before hatching and reared communally. After 10 months, a randomly taken sample was subjected to a standardized shallow water stressor. Hematocrit, hemoglobin, red blood cells count (RBC) and mean corpuscular volume (MCV) were obtained from stressed and non-stressed fish. DNA fingerprinting was used to confirm the clonal nature of the organisms and to identified the clonal line to which each fish belonged. 1 observed significant differences between clona] lines mostly in the hematocrit and MCV measured under no-stress conditions. Such differences are suggested to represent mainly genetic variance, on account of the common environment provided to all the experimental groups. The stress response ratio was lower than expected, mainly due to some unexpectedly high non-stress values. Heritability values (h$^2$) were medium to high for the no-stress measurements (mean 0.238) and very low or zero for the stressed groups'traits (excepting one high value of 0.484). 1 conclude that the use of communally reared clonal lines represents a good tool for the characterization of the physiological traits, thus allowing for their utilization as genetic selection criteria.

• Korean Journal of Ichthyology
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• v.30 no.3
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• pp.144-154
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• 2018

This study investigated the characteristics of fish communities at the Hangang River in Seoul from Jun 2016 to March 2017. During the survey period, there were 56 species of 17 families collected from 5 survey stations. The species that appeared mainly in the brackish water was Coilia nasus, Leiocassis nitidus, Lateolabrax maculata, Repomucenus olidus, Trachidermus fasciatus, Mugil cephalus, Chelon haematocheilus, Synechogobius hastus, Tridentiger bifasciatus and Takifugu obscurus. The migration fish of Anguilla japonica, C. nasus, Plecoglossus altivelis, Hypomesus nipponensis and T. obscurus appeared in this surveyed area. Korean endemic species were 11 species (17.9%) and accounted for a low rate. There were 6 species (10.7%) exotic species including Cyprinus carpio, Carassius cuvieri, Hypophthalmichthys molitrix, Megalobrama amblycephala, Lepomis macrochirus and Micropterus salmoides. The dominant species by stations were Acheilognathus gracilis (St. 1) and Hemibarbus labeo (St. 2, 3, 4, 5). Regarding the tolerance guild according to water quality, there were 3 (7.1%) sensitive species, 24 (42.9%) intermediate species, and 28 (50.0%) tolerance species. Twenty (35.7%) were insectivore species, 18 (32.1%) were omnivore species, 14 (25.0%) were carnivore species, and 4 (7.1%) were herbivore species, indicating the dominating presence of insectivore and omnivore fish species.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.192-204
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• 2013

Fish community structure and inhabit status of endangered fish species were investigated during April to November 2011 in Baebong Stream, Gangwon do, Korea. The number of fish species inhabiting the upper section (Stations 1~3, 5) was 14 and the stream bottoms were mostly composed of cobbles and boulders (Aa-type). Meanwhile, the number of fish species inhabiting the lower section (Stations 4, 6, 7) was 26 and the stream bottoms were mostly composed of pebbles, cobles and sand (Bb-type). A total of 26 species belonging to ten families were found in the stream during the survey period. The dominant and subdominant species were Rhynchocypris steindachneri (31.1%) and Squalidus multimaculatus (13.3%), respectively, and others such as Pungitius kaibarae (11.0%), Zacco koreanus (7.8%), Misgurnus anguillicaudatus (7.0%), Iksookimia pacifica (5.5%) and Z. platypus (5.3%) were followed in the order. Four species of Squalidus multimaculatus, Z. koreanus, I. pacifica and Liobagrus andersoni were endemic to Korea. And, Lethenteron japonica, L. reissneri, Pungitius sinensis and Cottus hangiongensis were endangered fish species in this stream. Oncorhynchus keta, L. japonica and Tribolodon hakonensis were anadromous species, and Plecoglossus altivelis was an amphidromous species. The similarity index based on species composition and abundance clearly divided the fish community structure of the Baebong Stream into two sections fragmented by a weir installed into the stream. It is necessary to install a fish ways on the weirs for a fish migration and movements.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.718-728
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• 2015

The fish community and inhabiting status of introduced fish were surveyed at nine stations of Gangeungnamdae stream from September 2013 to May 2014. A total of 36 species of fourteen families were collected from the survey stations and among them, Pungitius sinensis was identified as endangered species. There were nine Korean endemic species (25%) including Coreoleuciscus splendidus. Dominant species were Rhynchocypris steindachneri (St. 1), Zacco koreanus (St. 2, 4, 5, 6), Ladislabia taczanowskii (St. 3)), Zacco platypus (St. 7, 8) and Tribolodon hakonensis (St. 9). Of the 11 introduced species fishes in Gangeungnamdae stream, L. taczanowskii, Pungtungia herzi, Coreoleuciscus splendidus, Squalidus gracilis majimae, Pseudogobio esocinus, Rhynchocypris kumgangensis, Z. platypus, Z. koreanus, Koreocobitis rotundicaudata, Liobagrus andersoni and Coreoperca herzi were released from Han river water zone in Korean. Rapidly expanded population and distribution of introduces fishes were Z. platypus, Z. koreanus, P. herzi and S. gracilis majimae, but L. taczanowskii, C. splendidus, R. kumgangensis were not rapidly expanded population. Settlement but very small population fishes were C. herzi and L. andersoni. When reduced 3% fishes of relative abundance with previous data (1973), R. steindachneri, Orthrias toni, Iksookimia pacifica, Plecoglossus altivelis, P. sinensis and Gymnogobius urotaenia, and R. steindachneri was most reduced from 56.1% to 12.9%.