• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.229-232
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• 2022

Recently, production of offshore fisheries in Korea has been decreasing. Since production of offshore fisheries in 2016 fell below 1 million tons for the first time in 44 years, it has not recovered and has been decreasing. In order to cope with such a decrease in fishery resources, the TAC (total allowable catch) system is implemented internationally for fisheries resource management. Since 1999, South Korea has introduced the TAC system to perform resource management. In this paper, we propose an artificial intelligence-based fish classification and weight estimation system that can be used to investigate fishery resources of land observers essential for the implementation of the TAC system. The system consists of an app and a cloud server that automatically measures the body size and height of fish and takes photos using a terminal equipped with a lidar sensor. In the cloud server, fish classification is performed using a CNN-based efficientnet model and the weight of fish is predicted using automatically measured body length and body height information. Using this system, it is possible to improve the existing method in which the land observer manually writes after measuring the tape measure and weight in the stomach market.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.4
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• pp.282-288
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• 2008

Feeding ecology of the white-spotted conger eel Conger myriaster in the Southern Sea of Korea was examined. Specimens were caught monthly from January 2004 to December 2006. Primary prey items of C. myriaster included fish, shrimp, and crabs. C. myriaster exhibited a nocturnal feeding strategy and preyed upon a wide range of pelagic fish groups(e.g., Engraulis japonicus, Glossanodon semifasciatus, and Maurolicus muelleri). This species was also an opportunistic feeder that exploited the available prey in each area(i.e., fish in the A area and shrimp in the B area). The composition of the diet of C. myriaster exhibited seasonal fluctuations that were related to food availability during each season. The observed ontogenetic shifts in diet were relatively clear, despite substantial overlap between the 10 cm and 20 cm groups of C. myriaster.

• Ocean and Polar Research
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• v.23 no.3
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• pp.279-284
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• 2001

The natural high productivity of temperate coastal waters in Korea can be used in advantage to reduce the feed costs for the cage-cultured marine carnivorous fish species. By using the night-lights methods an alternative of supplementary feeding strategy can be offered to the cage farmers and maintain sound environmental conditions that could enhance maximum sustainable yields. The aim of this study was to investigate the effects of night-lights which shown positive results on feeding and growth in sea cage cultured rockfish, Sebastes schlegeli. The study showed that for the water around overhead illuminated sea cage, higher zooplankton density was observed at night than during the daytime. Increased amounts of for-age, evidenced by stomach content analyses were observed in the early evening, but decreased amounts were observed in the morning and afternoon. That is, feeding activities of the fish were most intensive from midnight to dawn. In a three month feeding experiment, the results showed that night-lighted groups were superior to groups with the highest feeding efficient. This study suggested that the evidence that night-lights superimposed on only day-lights enhance growth of rockfish in sea cages during summer and winter, with timing of exposure affecting growth of juvenile fish. The capability to control the feeding behavior of marine life via manipulation and external stimuli could considerably benefit the advancement of sea cage aquaculture in coastal areas.

• Journal of Aquaculture
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• v.17 no.1
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• pp.24-29
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• 2004

The high mortality of cultured turbot, Scophthalmus maximus was occurred from Gochang in June, 2003. Infect fish with iridovirus showed a lower feed intake and lethargic. These fish exhibited pale body color, extended abdominal and exophthalmus. Histopathological studies showed basophilic enlarged cells from kidney, spleen, gill, heart, muscle, stomach, intestine, liver and pancreas of these fish. In PCR amplification with red sea bream iridovirus (RSIV) specific primer set of a DNA fragment of 286 bp was obtained from infect turbot with the virus. The strain showed the high homologies with RSIV, LBIV (largemouth bass iridovirus), GSIV (giant seaperch iridovirus) and SBIV (sea bass iridovirus).

• The Korean Journal of Ecology
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• v.2 no.1
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• pp.9-14
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• 1978

The study was made to expand the knowledge of the ecology of Cobitis koreensis which is very common in the upper and middle part of rivers in western part of Korea. A number of C. koreensis are found in the creek of Jeonju-cheon located at Segjang-ri, Wanju-gun, Jeonrabug-do Province. The area studied has pebble bottoms. The flow velocity of the river ranges from 20cm to 40cm per second under normal conditions. The sex ratio of male to female was 1:1.34 and the female was 10~25mm larger than the male in total length. Length-frequencies in this population indicate that 20~40 mm fish group is underyearling, 40~60mm is a yearling, and 60~85mm is two-year-old. And the fish longer than 90mm in total length is regarded as being over three-year-old. Based on the ratio of gonadal weight to body weight, spawning in this species began in April and expanded well into June with water temperature 20~26。C, and the individuals became sexually mature over the two-year-old. The number of the eggs was counted from ten matured female fishes. The mean number of eggs in seven 72.6~81.4mm fishes was 908 (595-1, 229) and that of the rest three 86.0~89.0mm was 1, 674 (1, 337-2, 023). The contents of stomach in the other fifteen specimens captured in September 1977 were investigated. While the younger fed almost on the algae, the foods in the adult were largely aquatic insects.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.4
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• pp.372-378
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• 2012

The feeding habits of Hoplobrotula armata were studied using 269 specimens collected in the coastal waters of Geomun-do, Korea. The size of the specimens ranged from 5.6-56.8 cm in total length (TL). H. armata is a canivore that consumes mainly teleosts and decapods (shrimp, crabs and hermit crabs). Its diet also includes gammarid amphipods, cephalopods, polychaetes and copepods. Smaller individuals (<20 cm TL) fed mainly on fish, shrimp and crabs. The proportion of shrimp and crabs decreased as body size increased, whereas the consumption of fish gradually increased. Fish accounted for almost the entire stomach contents of individuals (larger than 40 cm TL).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.35-41
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• 2006

The feeding habits of Spanish mackerel (Scomberomorus niphonius) were studied based on the examination of stomach contents of 445 specimens collected from January to December 2004, in the Southern Sea of Korea. The size of Spanish mackerel ranged from 26.1 to 105.4 cm in fork length (FL). Spanish mackerel was a piscivorous fish which mainly consumed teleost fishes such as chub mackerel (Scomber japonicus) and anchovy (Engraulis japonicus). Its diet also included small quantities of shrimps, stomatopods, cephalopods, crabs, polychaetes, amphipods, cumaceans and copepods. Smaller individuals (<60 cm FL) consumed small fishes such as Engraulis japonicus and crustaceans. The portion of these prey items decreased with increasing fish size, and this decrease was paralleled with increased consumption of lager fishes such as Scomber japonicus and Cololabis saira. The prey size increased with the increase of fish size.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.2
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• pp.421-429
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• 2014

We investigated the feeding ecology of juvenile chum salmon (Oncorhynchus keta) during the critical early life stage prey selectivity of juvenile chum salmon during early marine migration in Korean waters at spring 2011. Salmon juveniles and zooplanktons were collected to draw with $20m{\times}5m$ gill net and $300{\mu}m$ mesh zooplankton net at each station on 11th-13th April n 2011. Collected zooplanktons were classified to 5 Phylum, 6 Class, 9 Order 17 Species in this study. Almost 76.4-100% species were classified to Phylum Arthropoda, dominant species was a species out of Hyperia galba of Order Amphipoda, Acartia spp and Paracalanus parvus of Order Calanoida. Collected salmon juveniles were grew up to average 4.7-5.4 cm fork length and average 1.0-1.5 g wet weight in whole station. Fish stomach content (mg/salmon) was heaver to 97.4, 82.4 and 63.2 mg wet weight/salmon in ST 2, 3, 4 than 20.4, 18.9 mg/salmon of ST 1, 5, because there are fish (sand eel, Hypoptychus dybowskii) and Krill (Euphausia) as prey in salmon stomach in ST 2, 3, 4. And ST 2, 3, 4 and 5 were dominated by Amphipoda as Hyperia galba, Themisto japonica and Gammarus sp., but ST 1 was dominated by copepod, because of absence of Amphipoda in the station. Therefore small Amphipoda as Hyperia galba was good prey for just released salmon juvenile in nature.

• Journal of fish pathology
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• v.14 no.1
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• pp.16-20
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• 2001

The pathogenicity of the extracted WSBV from the hepatopancreas, the lymphoid organ, the stomach and the heart of infected shrimps was examined after artificial infection in shrimps(Penaeus chinensis). In terms of the infection route, the strength of the pathogenicity of WSBV was in the order of intramuscular, oral and dipping method. The influence of rearing water temperature on the pathogenicity of WSBV was the strongest in the order of $30^{\circ}C$, $25^{\circ}C$, $20^{\circ}C$, and $15^{\circ}C$. The isolated WSBV from the diseased shrimps showed very high pathogenicity regardless of their sizes, even though there was difference in time to reach 100% mortality. Degenerated cells characterized by hypertrophied nuclei were found in various tissues such as the lymphoid organ, the hematopoietic tissue and the epidermis in the stomach.

• Korean Journal of Ichthyology
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• v.7 no.2
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• pp.160-170
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• 1995

The authors investigated feeding habit of river sculpin(C. poecilopus) were conducted at the Chiak streams from April 1993 to March 1994. The feeding habit of C. poecilopus was mainly acquatic insects, such as Ephemeroptera, Odonata, Plecoptera, Trichoptera, Coleoptera, Diptera, and Nematoda, teleost fishes, fish egg and terrestrial insects. Terrestrial insects in the stomach contents were found mainly in autumn, and teleost fish(Moroco oxycephalus) was in summer. Aquatic insects(Ephemeroptera, Trichoptera and Diptera) constituted the bulk of food items ingested during each season. The prey selection indices for Ephemeroptera were positively selected in summer, and negatively selected in autumn and winter, Tricoptera and Diptera were positively selected in autumn and winter, and negatively selected in summer. Additionally, analysis for stomach contents of guarding males suggests that the parental males eat their own eggs during egg guarding(filial-cannibalism).