• Parasites, Hosts and Diseases
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• 제54권3호
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• pp.363-368
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• 2016

We describe here the mass death of predatory carp, Chanodichthys erythropterus, in Korea induced by plerocercoid larvae of Ligula intestinalis as a result of host manipulation. The carcasses of fish with ligulid larvae were first found in the river-edge areas of Chilgok-bo in Nakdong-gang (River), Korea at early February 2016. This ecological phenomena also occurred in the adjacent areas of 3 dams of Nakdong-gang, i.e., Gangjeong-bo, Dalseong-bo, and Hapcheon-Changnyeong-bo. Total 1,173 fish carcasses were collected from the 4 regions. To examine the cause of death, we captured 10 wondering carp in the river-edge areas of Hapcheon-Changnyeong-bo with a landing net. They were 24.0-28.5 cm in length and 147-257 g in weight, and had 2-11 plerocercoid larvae in the abdominal cavity. Their digestive organs were slender and empty, and reproductive organs were not observed at all. The plerocercoid larvae occupied almost all spaces of the abdominal cavity under the air bladders. The proportion of larvae per fish was 14.6-32.1% of body weight. The larvae were ivory-white, 21.5-63.0 cm long, and 6.0-13.8 g in weight. We suggest that the preference for the river-edge in infected fish during winter is a modified behavioral response by host manipulation of the tapeworm larvae. The life cycle of this tapeworm seems to be successfully continued as the infected fish can be easily eaten by avian definitive hosts.

• 한국수산과학회지
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• 제45권1호
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• pp.50-55
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• 2012

We compared the nutritional requirements of whole larvae of the black seabream Acanthopagrus schlegeli, sweet fish Plecoglossus altivelis, olive flounder Paralichthys olivaeus and rock fish Sebastes schlegeli. The larvae were 20, 30, 14 and 5 DAH (or spawning) of black seabream, sweet fish, olive flounder and rock fish, respectively. Specific ${\alpha}$-amylase activity (mU/mg protein) was highest (8,324.9 mU/mg protein) in rock fish larvae (P<0.05). Specific trypsin-like protease activity was highest (11,330.1 mU/mg protein) in black seabream larvae (P<0.05), which also exhibited the highest activity, 685.5 mU/mg dry weight (P<0.05). The specific activities per mg protein and mg dry weight of black seabream were the highest (187.4 mU/mg protein and 11.3 mU/mg dry weight, respectively) (P<0.05). A/P, P/L and A/L ratios of rock fish were 1.47, 90.3 and 133.1, respectively (P<0.05). We present here basic larval digestive enzymatic nutritional requirement data.

• Fisheries and Aquatic Sciences
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• 제14권1호
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• pp.55-61
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• 2011

Fish larvae were collected monthly with an ichthyoplankton net from 18 stations (including four stations located in eelgrass beds) in Gamak Bay and Yeoja Bay, southern Korea, in 2007. In total, 33 species of fish larvae were collected, of which Engraulis japonicus (48.5%), Tridentiger trigonocephalus (21.5%), and Omobranchus elegans (9.2%) were dominant. Dominant species varied seasonally: Hexagrammos otakii during December and January, Pholis nebulosa during January and March, Acanthogobius flavimanus in April, T. trigonocephalus in May, E. japonicus during June, July, September, and November, and Sillago japonica in August. Dominant species also differed between sites inside and outside the bays. Leiognathus nuchalis, O. elegans, and T. trigonocephalus were more abundant inside, while H. otakii was more abundant outside. From cluster analysis, three groups were identified according to sampling months (January-April, May-September, and October-December) and two groups according to station (inside and outside bays). The occurrence of small larvae of almost all major fish species indicated that the bays were used as spawning and nursery grounds. An exception was Lateolabrax japonicus, whose specimens were relatively large (>19 mm TL), suggesting that this fish may spawn offshore, with its juveniles approaching the bays with growth.

• 한국양식학회지
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• 제19권3호
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• pp.178-182
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• 2006

이 연구에서는 해산어 초기 자어 사육 과정에서 자어가 섭이하는 로티퍼의 새로운 관찰 및 계수방법을 제시한다. 지금까지는 해산어 자어를 사육하면서 언제부터 로티퍼를 먹이로 이용 가능한지? 그리고 일령이 경과함에 따라 어느 정도 양의 로티퍼를 섭이하는지? 정확하게 분석할 수는 없었다. 왜냐하면 자어가 섭이한 로티퍼(몸통)는 소화기관내에서 소화되어 연구자가 관찰할 수 없었기 때문이다. 그러나 이 연구에서는 이러한 문제점을 해결할 수 있는 새로운 관찰 방법으로서 로티퍼의 저작기(trophi)를 이용하는 방법을 제시한다. 로티퍼는 각 개체마다 한개의 저작기를 가지며 이 저작기는 해산어 자어의 소화기관내에서도 소화되지 않고 그 형태를 유지한다. 따라서 이 연구 결과에 의하면 자어의 소화기관내의 저작기를 관찰하여 계수하는 방법(RTCM; Rotifer Trophi Counting Method)을 이용하여 로티퍼를 최초로 섭이하는 일령은 물론 자어의 일령이 경과함에 따른 포식 로티퍼 개체수를 정확하게 분석할 수 있다.

• 대한수의학회지
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• 제47권2호
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• pp.191-195
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• 2007

This study reveals the unusual case reported for the first time on the selective non digestion of yellow mealworm (Tenebrio molitor) larvae by arowana fish. In January 2005, an Asian arowana (Scleropages formosus) (red variety), from Daesang Tropical Fish Corporation, Seoul, Korea, mortality was observed due to unknown cause. No putative causal factors were suggested by bacteriological and parasitological examinations. Internal examination of the dissected stomach showed some undigested debris with mandible parts of mealworms attached to the mucosal lining of stomach wall. Feeding experiment of yellow mealworm (Tenebrio molitor) was conducted on the silver arowana (Osteoglossum bicirrhosum). Result showed that on the test group, fish released vomitous material containing undigested mandibles of mealworm was observed on the 24th day of the feeding experiment. Histopathological examination of the cross section of the stomach wall layers of the test groups, showed detached parts of the mucosal layer and gastric pits around the damaged area with intact mucularis tissues. While the control group fed with mealworm larvae without head part showed intact stomach wall layers consisting of gastric pit, mucosa and mucularis tissues. Fish on both treatments survived until the termination of experiment. The removal of mealworm larvae head before feeding probably help or aid in the fast digestion of these insect larvae.

• 한국수산과학회지
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• 제55권2호
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• pp.146-153
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• 2022

The vertical distribution and abundance of icthyoplankton in the southern waters of Jeju Island during June 2020 were investigated. Fish eggs and larvae were identified using the mitochondrial DNA cytochrome c oxidase subunit I (mtDNA COI) and the 16S rRNA gene. During this period, fish eggs of 23 taxa belonging to 21 families and larvae of 27 taxa belonging to 25 families were collected. Fish eggs were located mostly from the surface to 30 m depth of the water column. Larvae were located from the surface to 80 m depth of the water column. Vertical distributions of fish eggs and larvae were influenced by oceanography conditions such as temperature, salinity, and thermocline depth. No discernible difference in mean thermocline depth was observed between day and night.

• 한국어류학회지
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• 제18권2호
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• pp.129-140
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• 2006

제주도 서부 해역에서 어류 난 자치어의 계절별 출현현황을 조사하기 위해 2004년 9월부터 2005년 8월까지 총 5회에 걸쳐 각 계절별로 난 자치어를 채집하였다. 조사기간 동안 난과 자치어는 모두 여름철인 8월에 가장 많이 출현하고 있었다. 본 연구해역에서 조사기간 동안 출현한 전체 자치어는 총 10목 26과 51속 59종으로 이들 중 농어목 어류가 15과 41종으로 가장 많이 출현하였고, 다음으로 쏨뱅이목 2과 7종, 큰가시고기목 2과 2종의 순으로 출현하고 있었다. 계절별 자치어 출현현황에 있어서 출현종수는 8월에 25종으로 가장 많이 출현한 반면에 5월에 6종으로 가장 적은 출현종수를 나타내고 있었다. 계절별 자치어 출현량에 있어서 고수온기인 여름철에는 주로 멸치, 고등어류와 같은 회유성 어종들이 풍부하게 출현하여 우점을 이루고 있는 반면에 저수온기인 겨울철에는 쏨뱅이, 볼락과 같은 정착성 어종들이 우점을 이루고 있었다.

• 한국수산과학회지
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• 제36권5호
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• pp.486-494
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• 2003

Distribution of ichthyoplanktons and its relation to environmental factors (temperature, salinity, $chlorophyll\;\alpha$) around the Youngsan River Estuary of Mokpo, southwest coast of Korea were investigated based on the samples collected bimonthly from February to December, 2001. Unidentified fish eggs were most abundant $1,345\;eggs/100m^3$ in August, while eggs of Engraulis japonicus were most abundant $63\;eggs/100m^3$ in June. A total of forty species of fish larvae and juveniles belonging to the twenty families under six orders were caught, with six gobiids, four icefishes, four croakers and three herrings being represented. Fish larvae and juveniles peaked $17,757\;inds./100m^3$ in August, which consisted of $91.02\%$ of gobiids, $3.69\%$ of gunnels and $3.67\%$ of icefishes, and they were most abundant $7,467\;Inds./100m^3$ at St. 7. Cluster analysis based on the individuals of fish larvae and juveniles showed that six months were classified into two groups at the dissimilarity 70, the first was composed of June and August and the second was February and December and April and October were not clustered with any other months. In August when species diversity index was the highest, eight stations were classified into two groups at the dissimilarity 70, the first was composed of St. 1, 3, 4, 5 and 8 and the second was St. 6, 7 and 2. As a result from correspondence analysis, there is no effect of the environmental factors with a density of fish eggs and larvae, but correlation could be found between a density of fish eggs and $chlorophyll\;\alpha.$

• 한국환경보건학회지
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• 제26권2호
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• pp.67-69
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• 2000

Yellow tails (Seriola quinqueradiata) were purchased from the Jakalchi fish market located in Busna and examined for anisakid larvae. The collected larvae were classified by their morphologicaltypes. Of the 16 yellow tails exmained, seven (43.8%) were infected with the larvae. Among 90 larvae, 81 were collected from the omentum and 9 from the muscle. Anisakids were classified into five larval types, anisakis type I (56 larvae in number, 62.2%), Contracaecum type A (8, 8.9%) and type D (7, 7.8%) and Contracaecum type C (19, 21.1%). The present study revealed that Anisakis type I was the most common among the five larval types in the yellow tails caught in the South sea of Korea peninsula.

• 한국양식학회지
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• 제12권4호
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• pp.309-315
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• 1999

In order to understand the initial feeding time of larvae red marbled rockfish, Sebastiscus tertius changes of mouth size were investigated. Also, the fecundity of different size of red marbled rockfish broodstocks was measured. The broodstocks of red marbled rockfish, S. terius of $32.3\pm6.52 cm$ and larger than 45cm in total length spawned 296,648 and 600,000 larvae, respectively. About 50% was normal healthy larvae among the spawned ones. Mouth sizes calculated by the angle mouth opening and upper jaw length for newly spawned red marbled rockfish larvae were 0.263, 0.197 and 0.132 mm at D, 0.75D and 0.5D, respectively, when the upper jaw length was 0.186mm. Thereafter, 20 days old larvae showed 0.822, 0.617 and 0.411 mm in calculated mouth length at D, 0.75D and rockfish larvae grows, their upper jaw length gradually increased. 2 days old red marbled rockfish larvae possibly stated to feed rotifers and lasted their feeding for the another 35days, relatively long periods compared with other larvae fish. And 25 days old larvae possibly fed the newly hatched Artemia nauplii and lasted their feeding for the another 20 days, like other larvae fish. The proper supplying time of artificial feeds for the red marbled rockfish larvae seemed to be around 10 days after spawning.