• Journal of Fisheries and Marine Sciences Education
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• v.26 no.2
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• pp.421-429
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• 2014

We investigated the feeding ecology of juvenile chum salmon (Oncorhynchus keta) during the critical early life stage prey selectivity of juvenile chum salmon during early marine migration in Korean waters at spring 2011. Salmon juveniles and zooplanktons were collected to draw with $20m{\times}5m$ gill net and $300{\mu}m$ mesh zooplankton net at each station on 11th-13th April n 2011. Collected zooplanktons were classified to 5 Phylum, 6 Class, 9 Order 17 Species in this study. Almost 76.4-100% species were classified to Phylum Arthropoda, dominant species was a species out of Hyperia galba of Order Amphipoda, Acartia spp and Paracalanus parvus of Order Calanoida. Collected salmon juveniles were grew up to average 4.7-5.4 cm fork length and average 1.0-1.5 g wet weight in whole station. Fish stomach content (mg/salmon) was heaver to 97.4, 82.4 and 63.2 mg wet weight/salmon in ST 2, 3, 4 than 20.4, 18.9 mg/salmon of ST 1, 5, because there are fish (sand eel, Hypoptychus dybowskii) and Krill (Euphausia) as prey in salmon stomach in ST 2, 3, 4. And ST 2, 3, 4 and 5 were dominated by Amphipoda as Hyperia galba, Themisto japonica and Gammarus sp., but ST 1 was dominated by copepod, because of absence of Amphipoda in the station. Therefore small Amphipoda as Hyperia galba was good prey for just released salmon juvenile in nature.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.347-354
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• 2011

Aeromonas salmonicida is an important fish pathogen commonly associated with furunculosis in salmonids. Typical A. salmonicida strains have the surface virulence A-layer protein, a major virulence determinant encoded by the vapA gene. In this study, 880 chum salmon Oncorhynchus keta were collected from the east coast of Korea during 2006-2011, including 560 wild adults and 320 artificially hatched fry pools, and the presence of typical A. salmonicida was examined by PCR using the typical A. salmonicida-specific vapA gene primers. The results demonstrated that 34.5% of the samples (304/880 samples) were PCR positive, implying that a typical A. salmonicida infection is highly prevalent among chum salmon in Korea. Twenty typical A. salmonicida isolates were recovered based on their brown pigmentation on Trypticase Soy Agar (TSA) plates, which indicates the existence of the A-layer protein. Further biochemical analyses with the four randomly selected typical A. salmonicida isolates revealed some variations in their amino acid decarboxylation and carbohydrate fermentation activity. A phylogenetic analysis based on the entire vapA gene sequence suggested that the A. salmonicida isolates from chum salmon were clustered with those isolated from Atlantic salmon in Europe. Further study is needed to resolve such an interesting relationship in detail.

• Journal of Environmental Science International
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• v.31 no.10
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• pp.861-868
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• 2022

The Namdae stream in Gangneung-si is one of the rivers where salmon stock is mainly maintained by natural spawning rather than artificial seedlings. There are structures including weir, and fish distribution and movement characteristics can be different by these structures. In this study, we investigated the distribution and behavioral characteristics of salmon by sighting survey within 12 km immediately upstream of the river mouth between October 2021 and February 2022. As a result, salmon distributed within 9 km from rivermouth. There were more salmon in the lower reaches of Doosan weir than in the upper reaches of that. The main spawning ground for salmon was between 7-9 km from rivermouth and around the lower part of Doosan weir. Salmon behaved for spawning in the gravel-bed area and undercut slope of the mainstream, such as mating, digging the riverbed, and competition among males. Salmon moved more slowly in the gravel-bed area than sand-bed area. Doosan weir hinders the spawning migration of salmon by frequent flow changes and terraced fishway. This study provides primary information to understand the ecological changes of salmon by environmental changes in the Namdae stream.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.2
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• pp.61-72
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• 2007

The relationship between North Pacific chum salmon (Oncorhynchus keta) population and climate variability was investigated in the North Pacific ecosystem. Time-series for the Aleutian Low Pressure, Southern Oscillation, Arctic Oscillation, and Pacific Decadal Oscillation (PDO) indices dating back to 1950 are compared with the chum salmon catch using a cross-correlation function (CCF) and cumulative sum (CuSum) of anomalies. The results of CCF and CuSum analyses indicated that there was a major change in climate during the mid 1970s, and that the chum salmon population responded to this climate event with a time-lag. The PDO and chum salmon returns showed a highly significant correlation with a time-lag of 3 years, while the AOI with a time-lag of $6{\sim}7$ years. The favorable environments for fry chum salmon might cause better growth in the coastal areas, but higher growth rate during the early stage does not seem to be related to the improved return rate of spawning adults. Rather, growth in the Okhotsk Sea or the Bering Sea during immature stages has a significant correlation with return rate, which implies the size-related mortality process. The development of a local climate index is necessary to elucidate the effect of climate variability on the marine ecosystem around the Korean Peninsula.

• Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.186-190
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• 2007

We examined the genetic variability of Asian chum salmon (Oncorhynchus keta) populations using nuclear microsatellite (ms) DNA analysis with four polymorphic loci (OKM4, OKM5, OKM7, and OKM8) in 397 individuals from nine populations, including one in Korea, seven in Japan, and one in Russia. The msDNA gene diversity was highest in the Japanese populations, suggesting greater genetic variation in the populations in Japan than in populations in Korea and Russia. The pairwise $F_{ST}$ estimates based on our msDNA data showed that the Korean population was genetically different from the Japanese and Russian populations, and there were higher $F_{ST}$ estimates between Hokkaido and Honshu populations than between other population pairs. A neighbor-joining tree showed that the Korean population was distinct from two other clusters, representing the populations in Honshu and the populations in Hokkaido and Russia. These results suggest that the observed population genetic patterns of Asian chum salmon might be influenced by low or restricted gene flow.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.578-585
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• 2003

The chum salmon (Oncorhynchus keta) is an anadromous fish distributed all around the North Pacific. Artificial production and release of the juveniles are being made by Korea, Japan, Russia, Canada and the United States. It is important to set up some criteria identifying each stock in order to clarify each nation's right of harvest for the chum salmon resource. As an attempt to build such criteria, we analyzed sequences of a microsatellite DNA Ogo5 and the COIII-ND3-ND4L region of the mitochondrial DNA from chum salmons of Korea, Japan, and the United States. Ogo5 has 4 different alleles: allele A, B-1, B-2, and B-3. Allele B-3 is found only in 3 individuals out of 12 Korea salmons. The Japan salmons have the other 3 alleles and the America salmons have only 2 allots, A and B-1. Heterozygosity index (Ho/He) distinguishes the Korea (1.61) and Japan salmons (1.63) from the America ones (1.09). Seventeen different haplotypes are found in the COIII-ND3-ND4L region from 60 individuals,20 from each stock. The gene genealogy of the haplotypes revealed by TCS program shows that the Korea and Japan salmons are genetically closely linked, but that they are clearly distinguished from the America ones. Ten and eleven individuals of the Korea and Japan salmons have an identical haplotype. Nine individuals of the Korea salmons $(45\%),$ however, are separable from the Japan salmons by their own specific nucleotides. This result presents usefulness of the COIII-ND3-ND4L region as a genetic marker for identification of the chum salmon stocks.

• Fisheries and Aquatic Sciences
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• v.3 no.1
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• pp.44-48
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• 2000

In order to utilize chum salmon returned in the east coast of Korea, the changes in the properties of Yeonual-jeot (salted salmon roe) fermented at different temperatures were measured for obtaining the basic data for its commercial production. Moisture content of salted salmon roe was significantly lower than raw salmon roe, while other proximate components were in the reverse. pH was constant for 56 days fermentation at $5^{\circ}C$, but decreased with fermentation Reriod at 10 and $15^{\circ}C$. The contents of amino-nitrogen and VBN were almost in constant at $5^{\circ}C$ up to 28 days of fermentation, but increased very slowly at $10^{\circ}C$ and moderately at $15^{\circ}C$. TBA value, and the numbers of total viable cells and lactic acid bacteria increased over all fermentation periods, more at higher fermentation temperatures.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.94-99
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• 2003

Mitochondrial DNAs has been used frequently as genetic markers for the population genetic studies of salmonid fishes. Samples used in this experiment were chum salmons (Oncorhynchus keta) from Korea. We analyzed variation of mitochondrial NADH dehydrogenase subunit 3 gene (ND3) among 4 individuals of the Korea population. Genomic DNA was extracted from the liver of the chum salmon samples. Then, the ND3 gene was amplified by polymerase chain reaction (PCR) including the 3' region of cytochrome oxidase III gene (COIII) and the 5` region of NADH dehydrogenase subunit 4L gene (ND4L). The size of the PCR product was 752 Up and the sequences showed some genetic variation among those four individuals. Genetic variations were observed in 7 sites as single nucleotide polymorphism (SNP). Within the open reading frame of the ND3 gene which encodes 116 amino acids, 5 nucleotide substitutions were found. Both transitional and transversional changes occurred more frequently with transitional changes. Comparison of these sequences with the others of a Japanese chum salmon in GenBank showed 5 sites of SNPs. This study provided the basic information of SNP in ND3 gene among Korean chum salmons and demonstrated the possible use of the SNP data as a genetic marker.

• Korean Aquaculture
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• v.19 no.1
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• pp.52-57
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• 2007

Chum salmon의 알이 부화하는 동안 물곰팡이의 감염으로부터 보호하기 위해 알을 10 mg/L 염소농도의 하이포아염소산나트륨(NaOCl) 용액에 매일 15분간 수정란에서부터 발안기까지 처리하였다. 감염된 알의 수 및 발안기 알의 수는 부화 23일째 관찰하였다. 전체의 알에서 감염된 알의 비율은 대조구(11.3;59.3%)보다 NaOCl 처리한 실험구(1.8; 33.4%)에서 유의적으로 낮게 나타났다(P<0.01). 전체 알에 대한 발안란의 비율은 대조구(66.1:97.5%)보다 NaOCl처리한 실험구(85.9:98.6%)에서 유의적으로 우수한 경향을 보였다(P<0.01). NaOCl의 항균 활성은 알의 생존율을 향상시킨다. 따라서 NaOCl는 chum salmon의 난에 대한 물곰팡이의 감염에 대하여 아주 유용한 항균물질이라고 판단된다.

• Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.71-77
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• 2000

Rotifers inhabiting Oshipcheon (Samcheog-city), one of the natal streams of chum salmon in the east coast, were studied taxonomically. As a result, 19 species/subspecies were identified, and of which five rotifers are newly recorded from Korea: Cephalodella forficula, Dicranophorus forcipatus, Notommata glyphura, Bryceella tenella, and Habrotrocha collaris. Among these Korean new records, Habrotrocha collaris is also new to Asia.