• 한국수산과학회지
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• 제56권5호
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• pp.734-740
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• 2023

The effect of feeding frequency on growth performance, body nutrient composition, and hematological parameters of juvenile chum salmon Oncorhynchus keta was investigated. The juveniles (10.9±0.3 g) were fed commercial feed for 30 days with feeding frequencies of 1, 2, 3, 4, or 5 meal (s)/day (n=2 tanks per treatment) in a recirculating aquaculture system (RAS). Fish were fed to satiation at each of the feeding frequencies. At the end of the feeding trial, final body weight, weight gain, and specific growth rate of fish fed 2 meals/day were significantly higher than those of fish fed 1 meal/day(P<0.05); however, no difference was detected among the other feeding frequencies. Daily feed intake significantly increased with increasing feeding frequency, whereas feed and protein utilization efficiencies continuously decreased with increase in the feeding frequency. Among the treatments, fish fed 1 meal/day showed the lowest value in whole-body lipid content and total protein concentration in plasma. Taken together, the optimal feeding frequency for growth performance and feed utilization efficiency in chum salmon juveniles reared in the RAS was determined to be 2 meals/day.

• Ocean and Polar Research
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• 제34권2호
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• pp.165-173
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• 2012

A 26 day experiment was conducted to determine the effects of feeding and starvation on the survival, morphology, and histology in chum salmon (Oncorhynchus keta) fry. We included three experimental groups: starved, fed, and initial. The survival and growth rates were lower in the starved group than in the fed group (P < 0.05). In the starved group, survival began to decline after 16 days, and all fish had died after 26 days. We determined the effects of starvation on the morphometric parameters using the truss and classical dimensions. The dimensions in the head region were larger in the starved group than in the initial and fed groups. In contrast, the truss dimensions of the fed group were larger than those of the initial and starved groups. Starvation reduced the heights of the hepatocyte nuclei and of the intestinal epithelium (P < 0.05). The starved group also showed atrophy of the digestive structures and shrinkage of the foregut and midgut. Starvation led to the degeneration and atrophy of the exocrine pancreas, in which the lumen was markedly diminished and the folds of mucosa were less apparent. The hepatocyte morphology in the starved group was abnormal compared with that of the initial and fed groups, with highly compact, irregularly shrunken nuclei. Melanomacrophages were randomly distributed in the kidneys of the starved group, and their abundance increased rapidly during the experiment. In contrast, neither the initial nor fed group had any melanomacrophages. These results suggest that the nutritional parameters used in this study are useful indices of nutritional status in chum salmon.

• 한국가축번식학회지
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• 제21권3호
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• pp.311-319
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• 1997

This study was carried out to investigate the ultrastructural changes of spermatozoa obtained from 20 of 3-year-old male chum salmon(Oncorhynchus keta) collected and analysed in middle October in 1995. The ultrastructural changes of gonad of fingerlings were examined to describe the sex differentiation of this species. The results obtained in this study were as follows : In spermatozoa, the nucleus is dense and homogeneous. Two spheroidal mitochondria(about 350nm long) are situated in parallel between the nucleus and the axoneme. Spermatozoa mitochondria are assembled into an organized sheath surrounding the outer dense fibres and axoneme of the flagellar midpiece. The sheath flagellum is situated beneath the base of the sperm head. The primordial germ cells of 6.8~7.2${\mu}{\textrm}{m}$ in size, which were buried under fibrous mesenchymal tissue between gut duct and notochord of larva with a total length of 2.4cm at 50 days after hatching. In juvenile of 10.5cm in total length at 70 days after hatching, the gonad was occupied by bundles of oogonia. The dense drumstick bodies(large arrows) are observed in the nuclei of the primordial gonad and surrounding tissue cells of fingerling at 70 days after hatching. The oval Barr bodies(asterisk) are observed in the nuclei of the primordial germ cells under the mitosis(2n). Note the large mitochondria, ribosomes and rough endoplasmic reticulum in the cytoplasm. Accordingly, the fingerlings at 70 days after hatching are identified as the female(xx). In result, the gonadal sex differentiation begins from the 70 days after hatching in chum salmon.

• 한국해양학회지:바다
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• 제12권2호
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• pp.57-60
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• 2007

우리나라에서 연어(Oncorhynchus keta) 에 대한 관심은 1980년대 양양내수면연구소가 설치된 이후에 크게 증가하였다. 그 이후 연어방류사업이 점차 확대되어 최근에는 한반도의 18 개 하천에서 연어가 방류되고 있다. 하지만 아직 연어에 대한 충분한 연구 투자가 선행되지 않아, 연어에 대한 생태학적 이해는 부족한 편이다. 특히 지구환경은 지난 수십 년 동안 급격히 바뀌었고, 연어 개체군의 생물학적 특성도 변화하는 환경의 영향을 받아왔다. 연어 분포의 남방한계선에 있는 우리나라의 연어는 기후 및 해양의 변화에 민감하게 반응할 것이므로, 향후의 환경 변화를 주시해야 할 필요가 있다. 본 특별호에서는 북태평양에서 연어가 차지하는 수산생태학적 위치를 개괄하였고, 현재 우리나라에서 수행 중인 연어 연구의 결과를 요약하였다. 본 특별호가 우리나라 연어 연구의 방향을 제시하는 계기가 되기를 바란다.

• 한국수산과학회지
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• 제29권2호
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• pp.208-229
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• 1996

한국산 연어속에 속하는 연어, 산천어 및 무지개송어 3종의 골격학적 비교 연구를 하였다. 연어속 어류인 연어, 산천어, 무지개송어의 골격을 비교한 결과 두개골과 현수골의 형태나 결합 형태에서 3종간 차이를 나타내었다. 두부 골격중에서는 인설골, 상사골, 부설골, 서골의 형태에서 종간 차이가 뚜렸하였고 계통 분류학적 특징을 잘 나타내었다. 연어의 인설골은 산천어, 무지개 송어에 비하여 가늘고 길며, 끝이 뾰족한 특징을 가졌다. 상사골은 연어가 거의 정삼각형의 모양을 가지고 있으나 산천어나 무지개송어는 가늘고 길며 날개를 가진 형태였다. 본 연구에 나타난 골격 형질 분석 결과 알려져 있는 분류 형질외에 부설골의 형태, 전새개골, 설악골의 형태 및 미추골수 등이 새로운 분류 형질로 나타났으며, 산천어는 연어와 무지개송어의 중간 형질을 가지고 있는 종으로 나타났다.

• Fisheries and Aquatic Sciences
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• 제3권2호
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• pp.88-96
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• 2000

The present study estimated the variation of early survival of chum salmon families with respect to temperature and size after transfer to seawater. Heritability for seawater tolerance of half-sib families was also estimated at 45 days after hatching. Gametes were collected from 6 male and 18 female chum salmon to make 18 paternal half-sib families. Seawater tests were carried out at 3, 7 and $12^{\circ}C$ of $32\%$ seawater and compared with freshwater. Survival was significantly affected by seawater temperature. The highest seawater tolerance was obtained in 45-day old chum salmon at $7^{\circ}C$ seawater and the lowest seawater tolerance was obtained at $3^{\circ}C$. Overall survivals in seawater tolerance at $32\%$ varied among families. There were significant variance in fry survival among females (P=0.0001), and among males (P=0.0001). The heritabilities of survival in seawater in chum salmon were estimated to be 0.32-0.34 for the sire components at 45 days after hatching in 1998.

• Fisheries and Aquatic Sciences
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• 제14권4호
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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.

• 한국수산과학회지
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• 제41권3호
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• pp.182-187
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• 2008

Nine biochemical characteristics of female Oncorhynchus keta subpopulations that migrate to three streams (Namdaechun, Myeongpachun, Oshipchun) in Gangwon, Korea, were evaluated during November 2006: aspartate aminotransferase, alanine aminotransferase, creatine kinase, triglyceride, cholesterol, glucose, hemoglobin, and urea in the blood and RNA/DNA in muscle. The three subpopulations were identical morphologically, but differed in their biochemical characteristics. The RNA/DNA ratio could be useful for distinguishing the subpopulations. RNA/DNA ratios of the Namdaechun and the Myeongpachun and Oshipchun subpopulations were $3.52{\pm}0.7$ and $2.9{\pm}0.7$ and $2.4{\pm}0.8$, respectively. The difference was statistically significant (P<0.05). By contrast, the blood parameters were somewhat ambiguous.

• Fisheries and Aquatic Sciences
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• 제13권3호
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• pp.206-209
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• 2010

Chum salmon (Oncorhynchus keta) meat oil contained high amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) compared to oils extracted from other tissues of the fish. EPA and DHA occupied more than 25% of the total fatty acids in chum salmon meat oil. The main lipid classes in the meat oil were triacylglycerides and phospholipids. The major fatty acids of the molecular species composition of phosphatidylcholine isolated from the meat oil were DHA and EPA. DHA and EPA were the major molecular species in the phosphatidylcholine of chum salmon meat oil, representing 44% and 17%, respectively.

• 한국환경과학회지
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• 제31권10호
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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.