• Fisheries and Aquatic Sciences
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• 제18권3호
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• pp.325-332
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• 2015

An active stimulating method for juvenile fishes to drive escaping from mesh of the codend was examined by shaking canvas in the bottom trawl followed by shrimp beam trawl. Field fishing trials by a bottom trawl were carried out between the Geomoondo and Jejudo in west of South sea, Korea by conver-net methods to examine the effect on the reduction of juvenile fish as a discard catch by generating a shaking movement of the codend using two pieces of asymmetrical semi-circular canvas. The mean period of the shaking motion with the round canvas was 10-15 s, and the range of amplitude as a vertical depth change was up to 0.4-0.6 m when towing speed 3.4-4.3 k't as estimated by peak event analysis. The escape rate of juvenile fish in conver-net by total juvenile bycatch (codend and cover-net) in 14 trials increased from 20% in a steady codend to 34% using a shaking codend in the bottom trawl, while the marketing catch or total bycatch was similar between steady and shaking cod ends. There was no difference in the body size of the fish and species composition between the steady and shaking cod ends. Above results demonstrate a new method for bycatch reduction actually up to 18% using an active stimulating device, although further experiments are needed to increase an effective shaking motion of the codend in amplitude and period for more bycatch reduction.

• 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.

• 해양환경안전학회지
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• 제19권5호
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• pp.459-466
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• 2013

본 연구에서는 충남 연안에서 연안조망의 어획 특성을 파악하기 위하여, 2008년 3월부터 2009년 2월까지 매월 2~4회 연안조망을 사용하여 어획조사를 실시하였다. 조사 해역은 동경 125도 50분~126도 05분, 북위 36도 15분~36도 25분의 해역이었고, 총 19목 63과 96종이 채집되었다. 그 중 어류가 54종, 갑각류가 27종, 복족류 및 이매패류가 9종, 그리고 두족류가 6종이었다. 생체량은 어류가 51.4 %로 가장 많았으며, 갑각류는 34.2 %를 차지하였다. 꽃새우는 7월~11월에 출현량이 많았고, 12월부터 5월까지는 적은 양이 출현하였다. 연안조망의 목표종인 꽃새우는 전체 어획물의 2.1 %로 낮은 채집 비율로 출현하였으며, 꽃새우 이외 어종의 부수적 어획물의 양적 비율이 높아, 꽃새우 어획이 부수어획으로 어획되는 종들의 수산자원에 미치는 영향이 클 것으로 판단된다.

• 한국수산과학회지
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• 제36권4호
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• pp.378-388
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• 2003

Seasonal variations in abundance and species composition of fish assemblage around Narodo were examined. Fish samples were monthly collected by a beam trawl from December 2000 to November 2001. A total of 62 fish species representing 37 families were collected. Of these, Thryssa kammalensis, T. hamiltoni, Chaeturichthys hexanema, Johnius grypotus, Leiognathus nuchalis, Cynoglossus robustus and Setipinna taty were dominant species comprising $82\%$ of the total number of individuals. Species diversity indices ranged from 1.2 to 2.2 showing the highest values from September to November 2001. The fish assemblage was divided into three different groups by cluster analysis of the fourteen dominant species. The main residence species were J. grypotus, L. nuchalis, C. hexanema, C. robustus, Setipinna tenuifilis, T. kammalensis and Ctenotrypauchen microcephalus. Of the temporal species T. hamiltoni, Liparis tanakai and Erisphex pottii were collected In spring, and Muraenesox cinereus and Trichiurus lepturus were in summer and autumn. Principal component analysis revealed that seasonal variation in the fish assemblage was attributed to the abundance of temporal species due to seasonal variation of environmental factors such as water temperature and ecological pattern (polagic/demersal) of fish species.

• 수산해양기술연구
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• 제45권4호
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• pp.223-233
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• 2009

It has been considered that fishing areas for shrimp beam trawl have been in ruin because Korean local governments have permitted trawling into the areas limited by the fisheries local regulations from 1994. Physical and biological effects of the trawling were investigated in the study. Physical effects were investigated by optical methods such as trawling tracking by side scan sonar and comparing the gear both before and after trawling. Biological aspects were investigated by grab sampling of benthic animals, concentration of trace metals in sediment and a flux evaluation of ${NH_4}^+,\;{PO_4}^-,\;and\;SiO_2$ by coring. The fishing activity had physical impacts on the seabed but these recovered naturally in less than fourty days naturally, which increased the benthic biodiversity, increases the trace metal concentration of and nutrient flux into the seawater, especially phosphate and silicate. This method and these results can help in further studies looking for disturbances by fishing.

• 수산해양기술연구
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• 제49권4호
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• pp.419-431
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• 2013

It was turned out by the beam trawl survey in 2009 that flora of three phylum 16 species and fauna of eight taxa 68 families 97 species were inhabited in the Seomjin River estuary and western coastal waters of Namhae island. Winter season showed the most various appearance of species with 63 species and markedly several kinds of algae species, while summer season showed the lowest number of species with 44 species. However, the indices of species diversity and evenness were highest in summer, and vice versa in winter. Major dominant species were Crangon hakodatei, Leiognathus nuchalis, Asterias amurensis, Thryssa kammalensis, Luidia quinaria, Amblychaeturichthys hexanema, Oratosquilla oratoria, Charybdis bimaculata, Cynoglossus joyneri, Pennahia agentata. The 10 dominant species occupied at 81.4% of catch in number and 49.0% of catch in weight. There were seasonal fluctuations and differences by station in the Seomjin River estuary and western coastal waters of Namhae island, which brought to the difference of length structures, that is, bigger-sized individuals of major dominant species at station A (near to river estuary) than station C (near to ocean). Species compositions by season and by station were separated to two groups. Winter season showed a separated species composition from other seasons and station A exhibited a different species composition from other stations, which was located at near to the Seomjin River estuary.

• 한국수산과학회지
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• 제43권1호
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• pp.69-77
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• 2010

We examined shrimp and bycatch species composition in the shrimp beam trawl fishery off Wan-do, Korea(in the major or fishing ground)from December 2004 to November 2005. We observed a total of 103, 072 individuals in 96 taxa. By densities of individuals, 96.97% were shrimps, 1.20% decapods, 1.10% fish, 0.30% cephalopods and 0.43% other species. By catch weight, 57.29% were shrimps, 26.33% fish, 6.82% decapods, 4.64% cephalopods and 4.92% other species. In spring, the dominant bycatch species by biomass were Okamejei kenojei, Lophiomus setigerus, and Charybdis bimaculata. In summer, the dominant species were Charybdis bimaculata, Muraenesox cinereus, and Paralichlhys olivaceus. In autumn, dominants were Okamejei kenojei, Conger myriasler, and Sefipinna tenuifilis, and in winter they were Okamjei kenojei, Chaeturichthys stigmatias, and Sillago japonica. Bycatch species composition and individual species abundances differed significantly among seasons, probably indicating that variations were related to the life history characteristics of bycatch species. The diversity index was highest in October (2.797) and lowest in July (1.012). The July dominance index (0.569) was much higher than in other months; evenness was highest in September (0.856) and lowest in July (0.374). During the study period, the bycatch-to-shrimp ratio of this fishery varied from 0.063 in February 2005 to 11.031 in May 2005, with a mean of 3.363 These temporal variations may be linked 10 variations in reproductive behaviors and migration patterns of the marine animals sampled.

• 수산해양교육연구
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• 제28권1호
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• pp.211-220
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• 2016

Species composition of aquatic organism in the marine ranching area of Gunsan, Korea were investigated using shrimp beam trawl from May to December in 2010. A total of 91 species, $98,127ind./km^2$ and $877.6kg/km^2$ of aquatic organism were collected. Among them, species were included 60 species in Pisces, 21 in Crustacea and 10 in Mollusca. The individual dominant species, occupying over 10% of total individuals, were Latreutes anoplonyx($47,327ind/km^2$, 48.23%), Crangon hakodatei($11,578ind./km^2$, 11.80%) and Trachysalambria curvirostris($10,237ind./km^2$, 10.40%). And the biomass dominant species, occupying over 9% of total biomass, were Paralichthys olivaceus($135kg/km^2$, 15.4%), Okamejei kenojei($98.2kg/km^2$, 11.2%) and Portunus tribuberculatus($84.8kg/km^2$, 9.6%). From the cluster and MDS analysis based on Bray-Curtis similarity matrix of fourth root transformed data of number of species and individuals per unit area collected more than two times during this survey by each month and station was divided into three different groups. Group A showed seasonal similarity of characteristic of distribution in August and November, Group B in December and Group C in May.

• 수산해양기술연구
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• 제50권3호
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• pp.351-360
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• 2014

The experiments were carried out to decide the selective fishing gear of the shrimp beam trawl fishery. The model nets were made of General type, Double-level type and Grid type. The model experiments were carried out to test opening efficiency and towing tension. The experimental tanks were the flume tank [$8.0L{\times}2.8W{\times}1.4H(m)$] and the towing tank [$85L{\times}10W{\times}3.5H(m)$] in National Fisheries Research and Development Institute. The full scale experiments were carried out to compare the selectivity of General type net, Double-level type net and Grid type net in the southern sea of korea. The vertical opening (net height) of the model nets can be expressed as a function of the towing velocity as the straight line. The towing tension of the model nets can be expressed as a function of the towing velocity as the parabola. The shrimp catching rates of upper cod end in Boryeong and tongyeong were 78%, 9% respectively, but the rates of lower cod end were 23%, 91% respectively. The number bycatch rates of General type and Grid type were 23%, 11% respectively, and the weight bycatch rates were 34%, 31% respectively. A selective shrimp beam trawl net is Grid type in korea coastal sea.

• 수산해양기술연구
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• 제50권4호
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• pp.455-466
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• 2014

Seasonal variations in species composition of catches were explored using seasonal samples caught by shrimp beam trawl in the Geum river estuary in 2011. During the study period, total catches were collected 91 species as fish 47 species, crustacean 28 species, mollusca 4 species, gastropoda 5 species, shellfish 3 species and others 4 species. The dominant species were Exopalaemon carinicauda, Eriocheir leptognathus, Palaemon gravieri, Mugil cephalus, Acanthogobius hasta, Cynoglossus joyneri, Pennahia argentata and Coilia nasus. The amount of species in spring and summer was higher than in autumn. The diversity index (H') was 0.43~0.96, evenness index (EI) was 0.14~0.25, and richness index (RI) was 1.54~4.25. Using cluster analysis 91 species were divided into 4 groups. Group I appeared mainly in spring and summer. Group II appeared only in summer. Group III appeared in winter and spring, and Group IV in spring and autumn.