• 한국환경농학회지
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• 제42권1호
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• pp.63-70
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• 2023

Golden apple snails (Pomacea canaliculat) (GAS) are widely used for weed control in rice cultivation. However, concerns on the ecological risk of invasive GAS species are increasing. This study aimed to evaluate the overall impacts of GAS on weed control, abundance of aquatic animals and insects, and rice yield, in comparison with that from other biocontrol agents such as loach (Misgurnus mizolepis) and catfish (Silurus asotus), which are alternatives for biological weed control in rice paddy cultivation. Field experiments included five treatments; control, herbicide, GAS, loach, and catfish. During the rice growth, weed appearance and biological abundance were monitored, and at harvest, the rice yield was determined. Weed control efficiency was the highest for GAS treatment (100%), followed by that for herbicide (95.8%), loach (57.5%), and catfish treatments (31.7%). Insect abundance was considerably decreased in GAS treatment due to heavy weed removal, which affects the habitat of aquatic animals and insects. The amount of rice yield (unit: kg 10 a^-1) was in the order of GAS (798.9) > loach (708.1) = herbicide (700.7) > catfish (629.4) > control (496.0). Therefore, considering the weed control efficiency, biological abudance, and rice yield, loach could be a potential alternative for biological weed control in organic rice farming. However, the activity of the biocontrol agents are susceptible to environmental conditions; therefore, further studies under different conditions are essential to confirm these findings.

• 한국어류학회지
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• 제13권1호
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• pp.85-88
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• 2001

메기 Silurus asotus에서 염색체조작을 효과적으로 하기 위하여, 여러 온도 조건에서의 난할율과 제2, 제3 난할 시간의 평균화에 의한 체세포분열 간격지수 (${\tau}_o$)를 조사하였다. 빠른 난 발생과 비동시적 발생은 고온에서 더욱 뚜렷하게 나타났다. 메기의 체세포분열 간격지수는 $22^{\circ}C$에서 $21.5{\pm}1.4$분, $24^{\circ}C$에서 $18.5{\pm}1.2$분 그리고 $26^{\circ}C$에서 $14.0{\pm}2.1$분이었다. 3가지 수온조건과 ${\tau}_o$ 간에는 Y=-1.85X+21.9 ($R^2=0.9868$, Y는 ${\tau}_o$ 그리고 X는 수온)의 직선회귀가 성립되었다.

• 한국발생생물학회지:발생과생식
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• 제22권1호
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• pp.9-18
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• 2018

This study was conducted to investigate the skeletal development of bullhead torrent catfish, Liobagrus obesus larvae and to utilize them as basic data for the taxonomic study of Liobagrus larvae. Skeletal development was observed by being divided into cranium, visceral skeleton, shoulder girdle bone, pelvic girdle bone and vertebra. On the first day after hatching, the pre-larvae had an average total length of 7.92 mm, and a line-shaped parasphenoid ossified in the cranium. In the jaw bone, the dentary supporting the lower jaw and the maxillary supporting the upper jaw were ossified. In the anterior abdominal vertebrae of the vertebra, seven centrums began to ossify and five neural spines ossified simultaneously. On the 3 day after hatching, pre-larvae had an average total length of 8.95 mm, and the prefrontal ossified in cranium. The number of abdominal vertebrae was increased to 14, and three parapophysis developed from the front side. On the 24th day after hatching, post-larvae had an average total length of 15.2 mm and the epural bone ossified in coccyx. The parhypural bone was ossified, and ossification of coccyx and pelvic girdle bone was completed. On the 30th day after hatching, the average total length of the juvenile was 17.8 mm, and the ossification of cranium and visceral skeleton was all completed while the preorbital and three suborbitals were ossified in the orbital region of the cranium.

• 한국수산과학회지
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• 제45권2호
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• pp.139-145
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• 2012

Two feeding trials were conducted to evaluate the effects of experimental extruded pellets (EEPs) and commercial EPs (CEPs) on Far Eastern catfish $Silurus$ $asotus$ in pilot- (experiment I) and commercial-scale (experiment II) tanks. Four diets were prepared: three EEPs (EEP1, EEP2 and EEP3) that contained different amounts of tuna fish meal, soybean meal, and squid liver oil, and one CEP diet. In experiment I, three replicate groups of juveniles were fed one of the four EPs in pilot-scale tanks for 19 weeks. The weight gains (WGs) of fish fed EEP1 and CEP were significantly higher than those of fish fed EEP2 or EEP3. The highest feed efficiency (FE) was observed in fish fed the CEP diet ($P$<0.05), and the FE of fish fed EEP1 and EEP3 were significantly higher than that with EEP2 ($P$<0.05). In experiment II, juveniles were fed one of four EPs in commercial-scale tanks for 19 weeks. WG and FE values of fish fed EEP1 and CEP were higher than those of fish fed EEP2 and EEP3. The results of this study indicate that the dietary formulation used in EEP1 could be used as a practical feed for Far Eastern catfish.

• 환경생물
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• 제38권2호
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• pp.315-322
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• 2020

메기(Silurus asotus)의 기아 시 생존율, 생식소 중량지수(gonadosomatic index; GSI), 간 중량지수(hepatosomatic index; HSI) 및 장 중량지수(intestinosomatic index; ISI)와 신장세포, 장 상피세포 및 간세포의 조직학적 변화를 조사하였다. 생존율은 섭이군이 92.2±0.47%, 기아군이 74.4±2.59%를 보였으며, GSI, HSI 및 ISI는 기아군에서 가장 낮은 값을 나타내었다(p<0.05). 신장세포 핵의 높이, 장 상피세포 핵의 높이, 간세포 핵의 크기 및 간세포의 크기는 섭이군에서 가장 높은 값을 보였으며(p<0.05), 신장세포핵의 높이, 장 상피세포 핵의 높이 및 간세포 핵의 크기는 기아군에서 가장 낮은 값을 보였다(p>0.05). 멜라닌대식세포(melano-macrophages; MMs)는 기아 동안 신장에서 증가함을 관찰하였다. 신장의 MMs 증가 및 간세포의 수축현상은 메기의 기아 상태를 식별하는 지표로 이용할 수 있으며, 본 연구의 결과는 메기의 영양 상태 확인을 위한 기초 자료로서 의미가 있을 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제25권3호
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• pp.369-374
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• 2012

A $3{\times}2$ factorial experiment was conducted to determine the effects of dietary protein and lipid levels on the growth and body composition of juvenile far eastern catfish. Six diets were formulated to contain three levels of protein (20%, 30% and 40%) and two levels of lipid (9% and 17%). Triplicate groups of fish (initial body weight of 7.6 g) were hand-fed to apparent satiation for 66 days. Final mean weight was improved with increasing dietary protein and lipid levels, and the highest final mean weight was observed in fish fed the 40/17 (% protein/% lipid) diet. No significant difference was observed in final mean weight for fish fed between 30/17 diet and 40/9 diet. Feed efficiency of fish fed the diets containing over 30% protein levels with 9% and 17% lipid levels were significantly higher than those of fish fed the 20% protein levels. Feed efficiency of fish fed the 30/17 diet was not significantly different from that of fish fed the 40/9 diet or 40/17 diet. Feed efficiency and protein efficiency ratio of fish fed the 20% protein diets with 17% lipid level were significantly higher than those of fish fed 9% lipid diet. Daily feed intake of fish tended to decrease with increasing dietary protein and lipid levels. Moisture content of whole body in fish fed the 9% lipid diets was significantly higher than that of fish fed the 17% lipid diets at the same protein level, but the opposite trends were found for crude lipid content. Significant effects of dietary lipid were observed for most fatty acids, according to their relative values in the diets. The results of this study suggest that the protein requirement for maximum growth of juvenile far eastern catfish may be higher than 40%, and an increase of dietary lipid level from 9% to 17% can improve growth and feed utilization.

• 한국수산과학회지
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• 제14권1호
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• pp.32-36
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• 1981

1979년 8월 태국에서 Clarias batrachus 자어 100미를 도입하여 그 중 10미를 제주대학양식학과양어실험실에서 친어까지 사육하였다. 성장은 자어에서 29일후 체장 5cm 전후 체중 1.43g으로 성장하였고, 260일후에는 약 206g으로 성장하였다. 1980년 10월 11일 3미의 암컷에 Chorionic gona-dotrophin $1\sim2\;IU$ 씩 주사하여, 그 중 1미가 10월14일에 산난하여 약 1,500개의 수정난을 얻었고 22시간 후 완전히 부화하여 그후 먹이를 갈 먹고 자란 건강한 자어 약 1,300미를 얻었다.

• 한국수산과학회지
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• 제36권5호
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• pp.480-485
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• 2003

Morphology of the spermatozoa from the testes of the catfish (Pseudobagrus brevicorpus) was studied by transmission and scanning electron microscopy. The spermatozoa of P. brevicorpus are approximately $82.25\pm0.06\;{\mu}m$ in length and relatively simple cells composed of a spherical head, a short midpiece and a tail as in most teleost fish, The nucleus measuring about $2.00\pm0.02\;{\mu}m$ in length is depressed with a deep nuclear fossa of about $1.05\pm0.03\;{\mu}m$ in length three fifths of the nuclear length. The nuclear fossa contains the proximal and distal centrioles. The two centrioles are oriented approximately $150^{\circ}$ to each other. The mitochondria are arranged in two layers and their number is 12 or more. They are separated from the axoneme by the cytoplasmic canal. The axoneme is the 9+2 microtubular pattern and has inner but no outer dynein arms as in other bagrids. The axonemal fins were the closed to axonemal doublet 3 and 8. The axonemal fins and lost outer dynein arm are shared in Bagridae and the deep nuclear fossa is shared in Siluriformes. The axonemal fins observed in Bagridae and Amblycipitidae of Siluriformes might be the apomorphic character in Ostariophysi.

• 수산경영론집
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• 제52권3호
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• pp.39-55
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• 2021

The purpose of this paper is to confirm the trend of inland water fish farming in North Korea and to suggest a plan for inter-Korean cooperation. North Korea's inland water fish farming laid the foundation for production in the 1950s and 1960s, and production facilities were expanded until 1980. In the midst of the severe economic crisis in the 1990s, North Korea paid attention to inland water fish farming as an alternative to food production. The military took the lead in expanding the aquaculture industry and catfish farming was encouraged. In the Kim Jong-un era, North Korea's inland fish farming continues the tradition of catfish farming and promotes a policy of expanding inland cage farming. This study comprehensively reviewed recent inter-Korean relations, North Korea's food crisis and acceptability, and UN sanctions. As a result, inland water fish farming is the most promising field for inter-Korean cooperation in the field of fisheries. In the initial stage of inter-Korean cooperation in the field of inland water fish farming, humanitarian aid projects such as feed and seed support can be promoted. In the stage of expanding inter-Korean cooperation, knowledge sharing program and materials and facilities support projects can be promoted. Development cooperation and direct private investment are possible at the full-scale stage.

• 한국수산과학회지
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• 제40권3호
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• pp.141-146
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• 2007

We investigated the reproductive cycle of the striped eel catfish Plotosus lineatus. Specimens were sampled in the coastal waters of Sungsan and Jocheon, east of Jeju, Korea, from September 2001 to August 2002. The gonadosomatic index (GSI) in females and males were reached a maximum in June $(14.18{\pm}10.38)$ and July $(0.35{\pm}0.12)$, respectively. Based on histological observations and GSI variation, the reproductive cycle was classified into the following successive stages: in females, growing (September-April), mature (April-June), spawning (June-July), and degenerative and recovery (July-September) and in males, growing (August-December), mature (September-May), spent (April-July), and degenerative and recovery (June-August). The total length at 100% maturity exceeded 15 cm and the fecundity ranged from 525 to 1176 eggs. The fecundity was correlated positively with total length and body weight. Histological observations of the gonads suggest that this species is a spring-summer spawner with group-synchronous type oocyte development.