• Ocean and Polar Research
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• v.26 no.3
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• pp.433-438
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• 2004

Stress response to the seawater acclimation in coho salmon (Oncorhynchus kisutch) smolt was investigated. Salt concentration of rearing water was gradually increased for 3 days from freshwater to seawater (30 ppt salt level). The changes of serum concentrations of cortisol as a primary stress indicator, and as secondary indicators, glucose (GLC), lactate (LAC), triglyce.ide (TG), cholesterol (CHOL), sodium ion $(Na^+)$, chloride ion $(Cl^-)$ and enzyme activities (alanine aminotransferase, ALT: aspartate aminotrasferase, AST; lactate dehydrogenase, LDH) were quantified during the acclimation experiment. Among them, cortisol, LAC, TG, CHOL, ALT, AST concentrations showed rapid increase at the first exposure to the 10ppt salt level (day 1), and began to decrease to the constant values after day 2 of adaptation at 20ppt salt level. However, LDH concentration tended to decrease during the whole experimental period. $Na^+\;and\;Cl^-$ showed slight decrease at day 1, and increased to a little bit higher values after day 2 rather than those in freshwater. All the fishes started on taking a food after day 4 of seawater adaptation. From these results, to reduce osmotic shock inducible stress to fish in seawater acclimation, gradual increase of salt levels is recommended.

• Journal of fish pathology
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• v.35 no.2
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• pp.215-223
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• 2022

Disease including parasite, bacteria and virus cause serious mortality to salmonid fish in the aquaculture. In this study, we investigated the current disease status of the rainbow trout (Oncorhynchus mykiss) and coho salmon (Oncorhynchus kisutch) in Yanayang, Pyeongchang, Jeongseon and Yeongwol of Gangwon province in 2021 and performed molecular characterization of those pathogen. For parasites, Ichthyophthirius multifiliis was observed at 2 farms. For bacteria, we identified Aeromonas sobria from kidney of rainbow trout using phylogenetic analysis of gyrB gene. A. salmonicida were isolated from necrosis site of gill cover and fin in coho salmon and necrotic lesion of fin in rainbow trout. Phylogenetic analysis using vap gene indicated that A. salmonicida isolated in this study were clustered with previously reported A. salmonicida subsp. salmonicida isolates. For virus, JRt-Nagano type of infectious haematopoietic necrosis virus was detected in rainbow trout, but infectious pancreatic necrosis virus and Oncorhynchus masou virus were not detected. These results provide useful information for the prevention of disease spread and transmission when cultivating new species such as Atlantic salmon in Korea.

• Journal of fish pathology
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• v.30 no.2
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• pp.79-88
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• 2017

At the present, fish farms are suffering a lot of economic losses due to infectious diseases caused by various pathogens including aeromonad. Aeromonad is ubiquitous bacteria that causes infectious diseases. At least 26 species in the genus Aeromonas have been reported to cause fatal infections not only in salmonid fishes, but also in other freshwater and seawater fishes. Molecular techniques based on nucleic acid sequences of 16S rDNA and housekeeping genes can be used to identify the Aeromonas species. In this study, The genus Aeromonas was isolated from salmonid fishes of sixteen fish farms in Gangwon-Do, Korea and phylogenetically identified based on the sequences of 16S rDNA and housekeeping genes for Aeromonad, i.e. RNA polymerase sigma factor ${\sigma}^{70}$ (rpoD) or DNA gyrase subunit B (gyrB). Consequently, 96 strains were collected from Atlantic salmon (Salmo salar), coho salmon (Oncorhynchus kisutch), masou salmon (Oncorhynchus masou) and rainbow trout (Oncorhynchus mykiss), and 36 isolates were identified as the genus Aeromonas by 16S rDNA analysis. Thirty six Aeromonad isolates were further analysed based on rpoD or gyrB gene sequences and found Aeromonas salmonicida (24 isolates), A. sobria (10 isolates), A. media (1 isolates) and A. popoffii (1 isolates), indicating that A. salmonicida is a main infectious bacteria in Salmonid fishes in Gangwon-Do. It was also proved that the phylogenetic identification of Aeromonas species based on the sequences of housekeeping gene is more precise than the 16S rDNA sequence.

• Korean Journal of Animal Reproduction
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• v.13 no.1
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• pp.49-55
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• 1989

The Results of colchicine and pretreatment time have shown that the cells of Coho Salmon(Oncorhynchus Kisutch) were effectively injected 6 hours prior to the harvest at a final concentration of 10$\mu\textrm{g}$/g body weight. The cell-density from 8,000 cells/㎣ (=8${\times}$106 ml) was found as ideal. The best effect of hypotonic solution in proportion to the cell is 20 : 1 and 50 minutes. The model number of diploid chromosome in this species was 2n=60. The karyotype analysis proved that the diploid complement consisted of 19 pairs of metacentric-, 4 pairs of submetacentric- and 7 paris of acrocentric-chromosomes. The diagrammatic representation proved that the diploid complement consisted of 7 pairs of metacentric-, 2 pairs of submetacentric- and 1 pair of acrocentric-chromosomes.

• Journal of Aquaculture
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• v.3 no.2
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• pp.127-133
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• 1990

Growth Comparisons of two age groups of coho salmon, Oncorhynchus kisutch, underyearling and age one, were made at Chungmu Experimental Fish Culture Station from December 17, 1988 to April 26, 1989. During the first 66 days of experimental period, the fish of underyearling group grew from 167.0 g to 633.1 g in average weight and the feed coefficient (FC) and daily growth rate (DGR) were 1.1 and $2.0\%$, respectively. In the same period, the fish of age one group grew from 396.0 g to 854.6 g in average weight and the FC and DGR were 1.1 and $2.0\%$, respectively. During the second 63 days, the fish of underyearling and age one group grew up to 1171.9 g and 1239.7 g respectively. FCs of these two groups were 1.5 and 2.6, respectively and DGRs were $1.0\%$ and $0.7\%$, respectively. Underyearling fish consumed more feed and performed better FC and DGR than age one fish. FC and DGR sharply decreased as the fish weight increased. Therefore under-yearling fish of this species seems better as seeds for seawater cage culture. For this purpose it is necessary to increase smolting rate in the underyearling group fish within a single season.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.2
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• pp.115-118
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• 2000

The production of cultured coho salmon (Oncorhpchus kisutoh) in Korea has being increased year after year. Smolt being reared in freshwater suffer transferring into seawater and are farmed in cages for fattening. This handling processes including transportation, confinement into cages are unavoidable stress to fish in salmon farming and often end up to mass mortality, This study aimed to investigate the impact of handling process on the stress responses of coho salmon. The indicator of stress was measured by cortisol to be a first response, and for the second response test, glucose, triBlyceride, cholesterol, lactate and electrolyte of $K^+, Na^+, Cl^-$ in serum and the activities of alanine aminotrtnferase (ALT), aspartate aminotransferase(AST) and lactate dehydrogenase (LDH) were analyzed. As a result, the concentration of cortisol, glucose as well as LDH activity were significantly increased, whereas others showed no difference comparing with control group. It obviously demonstrated that handling process made fish stressful.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.2
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• pp.123-130
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• 1995

This study was performed to obtain the basic data on the serum components of several marine fish species commonly cultured in Korea. Blood samples taken from five species of fish were analyzed for various components of serum, total protein (TP), albumin (ALB), triglyceride (TG), cholesterol (CHOL), glucose (GLC), sodium (Na). Potassium (K), chloride (Cl), Phosphorus (P), lipase (LIPA), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The fish used were coho salmon(Oncorhynchus kisutch), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder ( Paralichthys olivaceus) and parrot fish (Oplegnathus fasciatuss) reared at the Chungmu Experimental Fish Culture Satation of KORDI. TP concentration of warm-water species (2.9-5.1 g/dl) was higher than that of cold-water species, and ALB concentration was ranged at the level of 1.2-1.9 g/dl. Coho salmon showed the highest ration of A/G(1.1), and the other species were about 0.5-0.6. The concentrations of TG and CHOL, components of lipids, varied with the different species. The concentration of TG was high, but CHOL concentration was low in olive flounder, while the reversed results were shown by sea bass. The sum of these two components was the highest with 600mg/d1 in olive flounder, and about 400mg/d1 for sea bass and rock fish, and 300mg/d1 for parrot lish and coho salmon. Concentration ot GLC in coho salmon and rock fish ranged from 61 to 76mg/d1 which were about lour times higher than that of flounder. The highest lipase activity was observed in coho salmon, while it was nearly nil in flounder. The reversed tendency was found for TG concentration. Mineral concentrations of Na, Cl and K were 160-204 mmol/l, 137-183mmo1/1 and 0.5-3.1 mmol/l, respectively, but no significant difference between the species was observed. However, the concentrations of P were high in relatively active species such as coho salmon and rockfish. AST activity in all species examined was higher than that of ALT with being highest in coho salmon. The highest ALT activity was found in olive flounder.

• Journal of Aquaculture
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• v.11 no.4
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• pp.547-556
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• 1998

This study was performed to obtain the basic data on the serum constituents of several marine fish spesies commonly cultured in Korea. Blood samples taken from six species of fish were analyzed for various components of serum, total protein (TP), albumin (ALB), triglyceride (TRIG), cholesterol (CHOL), glucose (GLC), lipase (LIPA), amylase (AMYL), aspartate transaminoferase (AST), sodium (Na), potassium (K), chloride (CI) and phosphorus (PHOS). The fish used were coho salmon (Oncorhynchus kisutch), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder (Paralichthys olivaceus), rock fish (Sebastes schlegeli), sea bass (Lateolabrax japonicus), olive flounder (Paralichthys olivaceus), parrot fish (Oplegnathus fasciatus) and jack mackerel (Trachurus jaonicus) reared at the Chungmu Experimental Fish Culture Station of KORDI when the water tempetature was ca. 16.5$^{\circ}C$. There were significant differences in TRIG, CHOL, LIPA and AMYZ among the species analyzed. TRIG concentratin were ranged 178~180mg/dl in jack mackeerel and rock fish, 126~159 mg/dl in olive flounder and sea bass, and 102~114 mg/dl in coho salmon and parrot fish, respectively. Jack mackerel showed the highest levels in CHOL (255mg/dl) and GLC(138mg/dl) among species. LIPA levels were recorded 256 U/dl in coho salmon, 41~42 U/dl in parrot fish and rock fisk, and 5~11 U/dl jack mackerel and sea bass, respectively. AMYL activity of coho salmon was measured as 2, 665 U/dl, and that of jack mackerel was 1,210 U/dl while sea bass showed 60 U/dl and parrot fish, olive flounder and rock fish had at most 5 U/dl. On the other hand, there was no significant difference in the concentration of Na and CI. Na and K were proved that they were negatively correlated in all the species. Generally, among blood components, PHOS and CHOL levels were different depending on environmental temperature of each fish species, especially in olive flounder. Rock fish and parrot fish showed high blood concentration of those components during low temperature period while olive flounder and jack mackerel reached high level during their optimal environmental temperature period. The electrolyte concentration and LIPA activity were high during low water temperature period, in general, but TP and ALB concentrations were high during optimal temperature period. The concentrations of TRIG, CHOL and GLC, those which were used as energy sourses, were different among species by season.