• 한국어류학회지
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• 제9권1호
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• pp.22-29
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• 1997

1994년 1월부터 1994년 12월까지 광양만 대도주변 잘피밭에서 채집된 베도라치의 식성을 조사하였다. 베도라치는 잘피의 잎에 부착하여 서식하는 단각류(카프렐라류 및 옆새우류)를 주로 섭이하였으며, 그 외, 새우류, 등각류, 요각류, 갯지렁이류, 주걱벌레붙이류 등을 소량 섭이하였다. 베도라치는 성장함에 따라 섭이된 먹이생물의 조성 및 크기의 변동이 뚜렷하였다. 체장이 작은 크기군에서는 요각류를 주로 섭이하였으며, 체장이 증가하면서 단각류를 주로 섭이하였다. 대체적으로 계절에 관계없이 단각류인 옆새우류와 카프렐라류가 주로 섭이되었으나, 그들의 섭이 비율은 계절에 따라 변하였다. 가을에는 옆새우류가 휠씬 많이 섭이되었으며, 다른 계절에는 카프렐류가 더 많이 섭이되었다.

• 한국어류학회지
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• 제18권3호
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• pp.216-222
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• 2006

2004년 1월부터 12월까지 부산 주변해역에서 채집된 참돔의 식성을 조사하였다. 참돔의 체장분포는 8.5~44.6 cm SL의 범위였다. 참돔의 주요 먹이생물은 집게류 (Anomura), 단각류 (Amphipoda), 게류 (Brachyura), 새우류 (Caridea), 갯지렁이류 (Polychaeta), 극피동물 (Echinodermata), 어류(Pisces) 등 매우 다양했다. 그 외, 복족류(Gastropoda), 이매패류(Bivalvia), 갯가재류(Stomatopoda), 두족류(Cephalopoda) 자포동물(Cnidaria), 등각류(Isopoda) 등도 소량 섭이하였다. 참돔은 성장함에 따라 먹이생물 조성에 있어 변화를 보였는데, 체장 8~15 cm SL에서 새우류의 점유율이 높았으며, 15~25 cm SL에서는 집게류와 갯지렁이류의 점유율이 높았다. 그리고 25 cm SL 이상에서는 극피동물류와 어류의 점유율이 높게 나타났다.

• 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.

• 수산해양기술연구
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• 제55권1호
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• pp.20-28
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• 2019

The feeding habits of Pacific bluefin tuna, Thunnus orientalis were analyzed using samples by large purse seine fishery in Korean waters from 2012 to 2017. The number of samples was 1,274 and the fork-length (FL) ranged from 34.6 to 218.0 cm. According to %IRI, the Important main prey items of immature individuals (below 91.4 cm in FL) were Pisces, Cephalopoda and Euphausiacea and those of mature individuals were Cephalopoda and Pisces. T. orientalis showed ontogenetic changes in prey item that Pisces was dominated in size class of 30-89 cm (FL), Cephalopoda in 90-179 cm (FL), and Pisces above 180 cm. As for seasonal changes in prey item, Cephalopoda was dominant in spring and Pisces was dominant in summer, autumn and winter. %F, %N, %W and %IRI cluster analysis divided area into three groups: Group A was dominated by Pisces; Group B was dominated by Cephalopoda, and Group C was dominated by Euphausiacea.

• Fisheries and Aquatic Sciences
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• 제22권1호
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• pp.4.1-4.10
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• 2019

Russian sturgeon (Acipenser gueldenstaedtii) is commercially important in Korea because its caviar is highly prized. Although the early ontogeny of the species has been described, behavioral modifications in response to various light intensities or diel photoperiodicity patterns have not been studied extensively. The objective of the present study was to examine the behavioral characteristics of hatchery-produced A. gueldenstaedtii prelarvae over a diel photoperiodic cycle. During a diel light cycle comprising 16 h of daylight (450 lx), 4 h of dim light (10 lx), and 4 h of darkness (< 1 lx), newly hatched A. gueldenstaedtii prelarvae exhibited negative phototaxis in daylight (day 0-day 2), and this early behavior was not significantly affected by changes of light intensities. Rheotactic and non-rheotactic aggregation into schools was typical between days 3 and 6. Under the diel light cycle conditions described, rheotaxis was not influenced by environmental light intensity as much as non-rheotactic schooling behavior. Post-schooling behavior, which progressed from day 7 to day 8, did not change significantly during the diel light cycle. The data from the present study could be of practical value in developing a visual guide for assessing the fitness and quality of Russian sturgeon prelarvae under diel light cycle conditions in hatcheries.

• 한국수산과학회지
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• 제54권1호
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• pp.64-72
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• 2021

The feeding habits of the Japanese jack mackerel Trachurus japonicus were studied in the Southern Sea of the Republic of Korea. To assess the effects of season, sampling was conducted in February (winter), May (spring), and August (summer), 2020. The total length of each fish was measured in 1 cm intervals. Diet composition showed the highest species diversity during winter. Diet composition changed from copepods to euphausiids as the total length of jack mackerel increased, except during winter. The most important seasonal prey were copepods in winter and summer and euphausiids in spring. Species diversity of the zooplankton community structure was highest in winter. Among the zooplankton communities, copepods were dominant in all seasons. Species with a high electivity index in all seasons were relatively large zooplankton of ≥2 mm. Jack mackerel had ontogenetic diet change, exhibited diet selectivity depending on size, and its feeding habits were affected by the zooplankton community structure.

• Fisheries and Aquatic Sciences
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• 제26권3호
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• pp.169-180
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• 2023

Oreochromis niloticus is the most ecologically and economically important fish in tropical and sub-tropical aquatic systems. Recently, due to sever anthropogenic stressors, hydrological variations and infestations of invasive alien species in Ethiopian water bodies, fish community structure and ecosystem of Lake Tana is changing alarmingly. So far, there is paucity of information on the morphometric relations and diet composition of O. niloticus in Lake Tana, gulf of Gorgora. A total of 309 fish samples were collected and their total length (TL), standard length (SL) and total weight (TW) were measured to determine morphometric relations; and gut contents were examined to identify most important food item in the diet of the fish. Results indicated that, the relation between TL and SL was significant (p < 0.001) and linear (SL = 0.942TL-2.41) while the relation between TL and TW was curvilinear (TW = 0.014 TL^2.8) indicating allometric growth. Among the total guts scrutinized, 53 (17.3%) of them were empty and the remaining 256 (82.7%) were non-empty. Phytoplankton constituted the largest bulk and occurred in 77% of the guts examined and volumetrically accounted 44.3%. Detritus and zooplankton had an intermediate importance by occurring 60.2% and 63.3% of all guts scrutinized and constituted about 25.6% and 15.5% of the total volume respectively. Contributions of macrophytes, insects, nematodes and unidentified food items were relatively low in their importance. Ontogenetic dietary shift was observed in the diet indicating an omnivorous feeding habit of the adult fish.

• Asian-Australasian Journal of Animal Sciences
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• 제29권5호
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• pp.615-623
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• 2016

Angiopoietin-like protein 4 (ANGPTL4) is involved in a variety of functions, including lipoprotein metabolism and angiogenesis. To reveal the role of ANGPTL4 in fat metabolism of sheep, ovine ANGPTL4 mRNA expression was analyzed in seven adipose tissues from two breeds with distinct tail types. Forty-eight animals with the gender ratio of 1:1 for both Guangling Large Tailed (GLT) and Small Tailed Han (STH) sheep were slaughtered at 2, 4, 6, 8, 10, and 12 months of age, respectively. Adipose tissues were collected from greater and lesser omental, subcutaneous, retroperitoneal, perirenal, mesenteric, and tail fats. Ontogenetic mRNA expression of ANGPTL4 in these adipose tissues from GTL and STH was studied by quantitative real time polymerase chain reaction. The results showed that ANGPTL4 mRNA expressed in all adipose tissues studied with the highest in subcutaneous and the lowest in mesenteric fat depots. Months of age, tissue and breed are the main factors that significantly influence the mRNA expression. These results provide new insights into ovine ANGPTL4 gene expression and clues for its function mechanism.

• Asian-Australasian Journal of Animal Sciences
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• 제7권1호
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• pp.75-81
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• 1994

To elucidate the relationship between steroidogenesis and sex differentiation in the duck, plasma, testicular and ovarian testosterone, estradiol-$17{\beta}$ and progesterone concentration in male and female embryo of day 11 to 27 (just before hatching) of incubation and in 1- to 7-day-old male and female duckling were investigated by radioimmunoassays. Plasma estradiol-$17{\beta}$ concentration in female embryos declined from very high at days 11 and 15 of incubation and remained at low levels after hatching. Male plasma estradiol-$17{\beta}$ concentration were always lower than those of the female throughout this period. Plasma testosterone and progesterone concentrations in both sexes were low during the embryonic stage, but then increased to peaks 3 days and 1 day after hatching, respectively. Estradiol-$17{\beta}$ contents were much higher in the left ovary than the right ovary or testes throughout the experimental period. The estradiol-$17{\beta}$ content of the left ovary was very high at day 15 of incubation, and decreased gradually thereafter. Both in right ovary and testes, estradiol-$17{\beta}$ contents were always low. Testosterone and progesterone contents in the left ovary were low from day 11 to 23 of incubation, and reached a peak 1 day after hatching. Progesterone content in the right ovary and testes were low levels over time period examined. Testosterone and progesterone contents were much higher in the left ovary than the right ovary and testes. The present results clearly demonstrate that the capacity of the embryonic left ovary of duck to synthesize estradiol-$17{\beta}$ and testosterone is much higher than that of the embryonic testis. It is suggested that estrogen secreted from the embryonic ovary earlier than day 15 of incubation has an important role in female sexual differentiation in the duck, and the sex of the avian species is basically male with homozygous sex chromosome (ZZ).

• 한국어류학회지
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• 제32권2호
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• pp.97-102
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• 2020

거제시 구조라 및 망치 연안에서 우점하여 출현한 까나리(Ammodytes japonicus) 자어는 조사기간인 2019년 1월과 2월 동안 총 208개체가 채집되었고 척생장의 범위는 1.46~8.00 mm였다. 까나리 자어의 주먹이생물은 요각류가 가장 우점하였고, 그 중 긴노요각목 요각류를 가장 많이 섭식하였으며, 검물벼룩목 요각류를 그 다음으로 많이 섭식하였다. 요각류 외에도 어류 난, 패충류, 갑각류 유생도 섭식하였으나 그 양은 많지 않았다. 까나리 자어의 성장에 따른 먹이생물 변화양상을 알아보기 위해 3개의 크기군으로 나누어 분석한 결과(≤2 mm, 3~4 mm, ≥5 mm, Notochord length), 성장함에 따라 긴 노요각목 요각류의 섭식비율은 점차 증가하고 검물벼룩목 요각류는 감소하였으며, 평균 먹이생물의 개체수와 부피 모두 증가하는 경향이 나타났다.