• 수산해양기술연구
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• 제52권1호
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• pp.72-77
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• 2016

We examined monthly changes in the rate of fishes by-caught by gape net with wings and their immature ratio in the coast of Yeosu and Jindo Island, Korea. A minus correlation between bycatch rate, the ratio of fishes except for anchovy, Engraulis japonicus, to all fishes collected by gape net with wings, and individuals of the collected anchovy was significantly observed, implying that as the anchovy catch decreased and the bycatch rate increased. Immature ratios by the dominant bycatch species during the study is the following; Leiognathus nuchalis was 72.7~99.0%, Sphyraena pinguis was 84.0%, Sardinella zunasi was 90.0%, others (Leptocephalus, Trichiurus lepturus, Ammodytes personatus, Sphyraena pinguis, Trachurus japonicas, Mugil cephalus and Erisphex pottii) were 100.0%. In order to decrease the high bycatch rates of immature fishes in spring and autumn, our study suggested increasing of codend mesh size and developing suitable bycatch reduction devices in a gape net with wings.

• 수산해양기술연구
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• 제57권1호
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• pp.25-33
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• 2021

Species composition and variation of catches in the coastal waters of Sinsan of Jeju Island were determined using samples collected by a set net from May 2014 to October 2015. During the survey period, a total of 55 species (51 species, 35 families and 11 orders in fishes, 4 species, 2 families and 2 orders in cephalopods) were occurred, and Perciformes (28 species) were dominant fishes in this area. In the number of individuals and biomass, the small pelagic fishes such as Trachurus japonicus and Scomber japonicus were occurred abundantly, and both species accounted for 95.9% of the total catch by a fishing logbook of a set net. In the results of length-frequency distribution of small pelagic fishes caught by a set net in Sinsan, T. japonicus showed a range from 3.5-19.1 cm (average 8.8 cm) and S. japonicus showed a range from 7.0-25.6 cm (average 16.8 cm). In addition, these were mostly immature fishes.

• 한국어류학회지
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• 제31권3호
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• pp.141-149
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• 2019

본 연구는 동해 중부 연안에 출현하는 명태(Gadus chalcogrammus)의 산란기, 체장-체중 관계(weight-length relationships, WLRs), 비만도(condition factor)를 조사하였다. 생식소숙도지수(gonadosomatic index, GSI))의 월변화를 통하여 추정한 명태의 산란기는 12월에서 3월이었다. 전반적인 체장-체중 관계식의 지수값 b는 2.806이었고, 2.778 (암컷)에서 2.980 (미성숙 그룹)의 범위를 나타냈다. b값은 암수 사이에서 유사하였으나, 미성숙 그룹과 비산란기 동안 성숙 그룹 또는 산란기 보다 유의하게 높은 값을 나타냈다. 비만도는 미성숙 그룹에서 성숙 그룹보다 유의하게 높았으나, 산란기와 비산란기, 암컷과 수컷 사이에서는 유의한 차이가 없었다.

• 한국어류학회지
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• 제23권2호
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• pp.135-144
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• 2011

거제도 구조라 사질 연안과 거제만 치어와 미성어의 종조성을 조사하기 위하여 구조라에서 2005년 3월부터 2006년 2월까지, 거제만에서 2006년 6월부터 2007년 5월까지 매월 1회 소형 빔트롤 (beam trawl)을 이용하여 채집하였다. 구조라 사질 연안에서 조사 기간 동안 채집된 어류는 총 6목 14과 20총, 224개체, 534.9 g 이었다. 주요 어종으로는 날개망둑, 황매퉁이, 돌팍망둑, 바닥문절, 날돛양태, 별넙치 등이 많이 채집되었으며, 이들 6종은 총 개체수의 83.9%를 차지하였다. 생체량에 있어서는 전체 생체량의 47.1%를 차지하였다. 거제만에서 채집된 어류는 총 4목 8과 14종, 1,406개체, 1,899.7 g 이었다. 주요 어종으로는 줄망둑, 양태, 점망둑, 문절망둑, 꾹저구, 풀망둑 등이 많이 채집되었으며, 이들 6종은 총 개체수의 97.7%를 차지하였다. 생체량에 있어서는 전체 생체량의 96%를 차지하였다. 구조라와 거제만에서 출현종수와 개체수는 비교적 고수온 시기에 증가하였고, 수온의 하강에 따라 급격히 감소하였다. 거제만은 조사를 시작한 6월 이후 증가하든 양상을 보여 출현종수는 9월, 개체수는 8월에 최대를 기록하였다. 구조라의 출현종수와 개체수는 불규칙한 양상을 보였는데 특히 11월에 개체수와 생체량이 가장 높았다.

• 한국어류학회지
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• 제29권2호
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• pp.117-123
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• 2017

본 연구는 서해 중부 연안에 출현하는 쥐노래미 (Hexagrammos otakii)의 위내용물 분석을 통하여, 위내용물 조성과 성장 및 계절별 식성변화를 분석하였다. 쥐노래미의 전장 (total length, TL)은 5.6 cm에서 32.4 cm의 범위였다. 쥐노래미는 단각류 (amphipods), 새우류 (carid shrimps), 어류 (teleosts)를 주로 섭식하였고, 그 외 다양한 저서 갑각류와 무척추동물을 소량 섭식하였다. 새우류와 어류는 미성어 (immature)와 성어 (mature)의 위내용물에서 공통적으로 우점하였다. 단각류와 갯지렁이류 (polychaetes)는 그 다음으로 우점하였는데, 단각류는 작은 크기의 어류에서, 갯지렁이류는 큰 크기의 어류에서 그 비율이 더 높았다. DISTLM (distance-based linear modelling) 결과, 쥐노래미의 위내용물은 전장, 계절, 수온에 따라 유의하게 변하였지만, 성숙도와는 관련이 없었다.

• 수산해양교육연구
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• 제27권1호
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• pp.308-318
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• 2015

In order to improve the competitiveness of Korean large purse seine fishery, the purpose of this study is to find out the problems and present the improvement of the production structure of Korean large purse seine fishery by comparing to the production structure of Norwegian purse seine fishery. Norwegian purse seine fishery has been operating labor and energy-saving systems through a single wire operation and avoiding fishing competition through the introduction of IVQ system with different types of fishing vessel and obtaining benefits from Leading fishery management integrated with fish pumps and cooling water systems. In contrast, our country has a large purse seine fishery issues such as high cost and low efficiency of production structures, the volatility of mackerel resources, the lack of leading fishery management after catching fishes, the reduction of fishing ground in accordance with the North East Asia EEZ system. To solve these problems, initiatives to improve the structure of our large purse seine fishery are as follows: First, Implementing the promotion of the effective immature fishes management and establishing Korea-China-Japan resource management system. Second, the promotion of reduction of fleet size, the review of possible single fishing operation, leading out to strengthen its competitiveness by switching to energy-efficient production systems through enhanced efforts at fisheries catches steps. Third, it is necessary to realize corporate through the diversification of business areas and the large-scale commercialization of production structure.

• Fisheries and Aquatic Sciences
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• 제26권4호
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• pp.256-267
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• 2023

The suitability of any fish species for successful aquaculture requires basic information on its reproduction and growth. This study investigated some facets of the reproductive biology of Synodontis shall (Mochokidae) from River Siluko in Nigeria. Fish samples were collected forth-nightly for a duration of fourteen (14) months-March 2015 to April, 2016 with the assistance of artisanal fishermen. Fishes were identified using taxonomic guides and standard techniques were used for determination of sex ratio, gonad maturation and fecundity. Linear regression method was used to define the correlation between fecundity and fish length, body weight and ovary weight. Results showed that sex ratio did not indicate a significant divergence (p > 0.05) from the 1 male to 1 female distribution ratio (1:1.41). Gonad morphology revealed paired gonads. Testes and ovaries were classified into four maturity stages: immature, resting, ripening and ripe. Gonadosomatic index ranged from 0.04 to 5.68 (males) and 0.03 to 20.19 (females). Absolute fecundity ranged from 1,014 to 4,520 eggs (mean = 2,592 eggs) and did not correlate significantly (p > 0.05) to ovary weight. This study has contributed to existing data on the biology of freshwater fish species in Nigeria and provided valuable information for fishery management tools in the conservation and utilization of this valuable freshwater fish species.

• 수산해양기술연구
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• 제51권1호
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• pp.42-49
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• 2015

According to the catch condition of Scomberomorus niphonius in autumn season affected greatly, the catch price for the set net fishery. Catch production and the selling price were relatively even except 2009 showing a great big blooming jellyfish of Nemopliema nomurai in 2008~2011. The fishing cost of the set net fishery in Yeosu has increased gradually by the decrease of catch production and unexpected environmental change like as jelly fish blooming. The increase of fishing cost diminished net income and caused a negative impact in profitability. The lowest Fisheries ratio of gross profit to gross costs the set net fishery were appeared 60.2% in 2010, respectively. Bycatch was highest in 2008 and lowest in 2009. In general, the bycatch was occurred from May to July every year and when Scomber japonicus was most dominant in the catch price by bycatch had a advantage in the profit side. However, the catch increase of immature small fishes by the bycatch, which will bring about the decrease of fisheries resources. Finally, the present state in set net fisheries will act as a defect on the long-term management of fisheries resources.

• 생태와환경
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• 제40권2호
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• pp.337-345
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• 2007

2004년부터 2005년에 걸쳐 옥정호 육봉형 은어(Plecoglossus altivelis)의 성장에 따른 식성 및 섭식기관의 변화를 조사하였다. 호소에 서식하는 체장 $25{\sim}40$ mm의 후기자어는 요각류, 물벼룩류 및 윤충류를 주로 섭식하였고, 체장 $50{\sim}60$ mm의 치어는 파리목의 깔다구류, 요각류 및 물벼룩류를 주로 섭식하였다. 반면에 추령천에 소상한 $60{\sim}70$ mm의 치어는 동물성 먹이와 조류를 같이 섭식하였으며, 70mm 이상의 미성어는 Synedra, Cymbella, Navicula 및 Pinnularia와 같은 부착 조류를 주로 섭식하였다. 또한 성장 및 먹이생물과 관련하여 이(teeth)와 위 (stomach)의 형태도 바뀌었다.

• 한국어병학회지
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• 제30권2호
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• pp.97-105
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• 2017

Parasitic leeches could directly (through causing poor growth, anemia and wound in the fish) and indirectly (by predisposition of the fish to secondary bacterial and fungal infections) affects their hosts. In the present study, fishes that were attacked by leeches in natural and experimental environment were studied. Pathologic samples were obtained from damages at the site of leech bite, as well as kidney and liver of the fish. Histopathological examination revealed numerous lesions at the site of leech bite including tissue demolition, detachment at the site of leech bite in the epidermis of epithelial tissue in the skin, destructed nucleus in epithelial cells of the skin plus necrosis in the damaged skin and weak inflammatory penetration to acute necrotic damages along with piercing dermis layer. Pathologic lesions in the kidney included some changes such as proliferation by increasing glomerular cells and membrane cells in capillary vein of the kidney, blood cell necrosis in kidney with infiltration of white blood cells mainly mononuclear and less polymorphonuclear which are the symptoms of anemia due to blood feeding and sucking by leeches. There was also a chronic kidney infection probably originated from another part of body such as skin. Moreover, leeches caused hemorrhagic anemia due to blood consumption of the hosts, which led to observation of immature red blood cells. Also results showed that diseases induced by leeched in fish could be acute or chronic, which depends on size of fish, species of leech and severity of infection.