• 생태와환경
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• 제37권1호통권106호
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• pp.130-136
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• 2004

저수지화성향을 띤 낙동강은 수체가 정체되는 시기에 높은 동물플랑크톤 밀도를 보인다. 이 시기의 높은 치어개체군 밀도는 지각류 개체군 밀도의 감소와 윤충류 개체군 밀도의 증가를 유도하는 주요요인으로 제시되었다. 본 연구에서는 실험실실험을 통해 치어의 먹이선호도와 포식이 낙동강 동물플랑크톤 군집에 미치는 영향을 평가하였다. 여러 종류의 치어의 먹이선호도 및 크기가 다른 치어의 먹이선호도를 실험실 수조내에서 평가하는 한편, 대형 수조에서 이들 치어의 포식이 동물플랑크톤군집에 미치는 영향을 모니터링 하였다. 실험에 사용된 세종류의 치어 (Hyporhamphus sajori, Rhinogobius brunneus, Opsariichtys uncirostris) 및 크기가 다른 치어 (O. uncirostris) 모두지각류 Moina micrura에 가장 높은 먹이선호도를 나타냈다. 야외수조에서 실시된 실험에서 치어의 포식은 지각류 M. micrura를 억제하는 한편 윤충류인 Polyarthra spp.의 우점을 유도하였다. 본 실험결과. 치어의 섭식은 낙동강에서 동물플랑크톤 군집구조를 결정하는 중요한 요인으로 사료된다.

• 수산해양기술연구
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• 제55권3호
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• pp.181-189
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• 2019

Discarding juvenile fishes under girth 16 cm nearly equal to inner perimeter of codend mesh size collected by a cover net method in bottom trawl. The body size of the main five species (mackerel, horse mackerel, sea bream, melon seed and black throat seaperch) was measured for their body length, girth, weight, height and width and analyzed size selectivity. Frequency of penetrating fish as retention in a cover net was less than 40% of total number of juvenile discarding fish. The most of body length or girth of five species were significantly different between in the codend and in the cover net. The 50% selection girth in the cover net ranged 8-11 cm were smaller than those in the codend ranged 9-13 cm by the species respectively. The 50% selection body length was significantly related with the ratio of body height (H) by body width (W) both for in the codend or in the cover net while 50% selection girth was not significantly related with H/W. Furthermore 50% selection fish size by fish species between in the codend and in the cover net was not significantly different both in body length or girth. Therefore, the girth selectivity represented possibly as one unique value regarding fish body shape was considered as more useful method for multi-species catch in trawl.

• 한국수산과학회지
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• 제36권4호
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• pp.372-377
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• 2003

Feeding habits of juvenile Liparis tanakai collected from the eelgrass bed in Kwangyang Bay were studied. L. tanakai (2.0-6.0 cm SL) was a carnivore which consumed mainly amphipods (caprellids and gammarids) and caridean shrimps. Its diets also included a large amount of copepods, polychaetes and small fishes. Three distinct ontogenetic feeding groups were noted: (1) the individuals of 2.0-2.5 cm SL preyed heavily on copepods, (2) individuals of 2.5-4.0 cm SL fed mainly on amphipods. (3) individuals over 4.0 cm SL preyed mainly on caridean shrimps and small fishes. The dietary breadth of each size class showed relatively low value, and this means that juvenile L. tanakai depends on only few kinds of food organisms.

• 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.

• 한국수산과학회지
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• 제55권1호
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• pp.23-29
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• 2022

This study was carried out to clarify the egg, larvae and juveniles development of Misgurnus anguillicaudatus, and relationships of M. anguillicaudatus and M. mizolepis, Cobitididae Fishes. The adult fishes were collected in Samsan-cheon, Haenam-gun, Jeollanam-do, Korea and their spawning inducement was carried by ovaprim injections. The egg shape was circular and the size was average 1.12 mm. The eggs were hatched at 61 to 72 h after fertilization. The newly hatched larvae had an average 3.23 mm in total length (TL). At 5 days after hatching, the larvae reached to post larval stage and they were 10.3 mm in TL. At 19 days after hatching, it reached to juvenile stage and was 25.3 mm in TL. The egg size of M. anguillicaudatus was almost same as M. mizolepis but the hatching period of M. anguillicaudatus has taken longer. It was possible for interspecific distinguishability of M. anguillicaudatus and M. mizolepis when their larvae reached to juvenile stage by the development of keel-like ridges.

• 한국물환경학회지
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• 제29권6호
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• pp.746-753
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• 2013

The aim of this study was to evaluate artificial fish shelter, which was known to increase prey survival and expand habitat space to improve species diversity and fish communities in a freshwater ecosystem. The experiment was performed at an outdoor test-bed for three months from 2011 by comparing the responses to adjustments in the volume of the artificial patch (juvenile fish shelter, JFS) in the control and experimental groups. Analysis of the environmental conditions over two periods (Period1 ~ 2) showed minor differences in the physichemical characteristics of water quality, phytoplankton, and zooplankton biomass, thus, allowing comparative analysis of feeding ecology. However, high water temperature conditions in Period1 ($25.6{\pm}2.0^{\circ}C$), affected the predation activity of the piscivorous fishes, Coreoperca herzi (C. herzi, size $89{\pm}4mm$). Survival rates of the prey fishes, Rhynchocypris oxycephalus (R. oxycephalus, size $29{\pm}1mm$), improved as the patch volume increased and were higher than those of the control group by 35.9 ~ 46.7%. Analysis showed that JFS reduced the chances of predator-prey encounter, and thereby minimized prey vulnerability.

• 한국발생생물학회지:발생과생식
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• 제19권1호
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• pp.25-31
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• 2015

We have launched an investigation for Embryonic Development, Larvae and Juvenile Morphology, of Buenos aires tetra in order to build basic data of Characidae and fish seeding production. We brought 50 couples of Characidae from Bizidduck aquarium in Yeosu-si, Jeollanamdo, from Korea on March of 2015. We put them in the tetragonal glass aquarium ($50{\times}50{\times}30cm$). Breeding water temperature was $27.5{\sim}28.5^{\circ}C$ (mean $28.0{\pm}0.05^{\circ}C$) and being maintained. The shape of fertilized egg was round shape, and it was adhesive demersal egg. The egg size was 0.63~0.91 mm (mean $0.74{\pm}0.07mm$, n=20). After getting fertilized egg, the developmental stage was gastrula stage, and embryo covered almost two-thirds of Yolk. Incubation was happened after 16 hours 13 minutes from gastrula stage, and the tail of juvenile came out first with tearing egg capsule. Immediately after the incubation, prelarvae had 3.78~3.88 mm length (mean $3.84{\pm}0.04mm$, n=5), and it had no mouth and anus yet. 34 days after hatching from the incubation, juvenile had 8.63~13.1 mm (mean $10.9{\pm}1.66mm$), and it had similar silver-colored body shape with its mother.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2003년도 춘계 수산관련학회 공동학술대회발표요지집
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• pp.158-159
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• 2003

Although the sub-chronic toxic effects of metal on fishes are well documented, that is mostly in fishes exposed to waterborne metal but few studied have been conducted on the effects of dietary metal (Handy, 1996). The realization that dietary uptake of metal is a major cause of long-term contamination in wild fish has renewed interest in the nutritional and toxicological effects of metal in the food of fishes (Handy, 1996). (omitted)

• 수산해양기술연구
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• 제50권3호
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• pp.334-341
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• 2014

The diet composition of juvenile Korean piscivorous chub, Opsariichthys uncirostris amurensis were studied using 277 specimens collected from January to December 2004 in the surf zone of Nakdong river estuary. The size of Opsariichthys uncirostris amurensis ranged from 2.6 to 9.1 cm in standard length (SL). Opsariichthys uncirostris amurensis was carnivore that consumes mainly amphipods and insects. Its diet also included small quantities of polychaetes, fishes, and algae and plants. Opsariichthys uncirostris amurensis showed ontogenetic diet change. Smaller individuals (< 4 cm SL) mainly consumed amphipods. The portion of these prey items decreased with increasing fish size, and this decrease was paralleled with increased consumption of larger preys such as polychaetes and fishes. Insects were preyed moderated values in all size classes. Opsariichthys uncirostris amurensis diet also showed diel change with consuming more on amphipods and polychaetes during day.

• 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.