• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.41-48
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• 2015

Juvenile banded catfish(Pseudobagurus fulvidraco, mean length $10.4{\pm}0.37cm$ and mean weight $14.5{\pm}0.46g$) were exposed to several nitrite(${NO_2}^-$) concentrations for 96h at pH levels of $6.18{\pm}0.54$, $6.5{\pm}0.30$ and $7.07{\pm}0.22$. The result showed that cumulative mortalities of fish to ${NO_2}^-$ levels of 12.4, 19.8, 33.9 and 53.6 mg/L at pH levels of $6.18{\pm}0.54$ were 20, 25, 40 and 85%, respectively. At pH $6.5{\pm}0.54$, mortalities to ${NO_2}^-$ 22.4, 36.4, 45.3 and 63.2 mg/L were 25, 35, 50 and 100%, respectively. At pH $7.07{\pm}0.22$, mortalities to ${NO_2}^-$ 25.5, 45.7, 56.3 and 66.4 mg/L were 0, 55, 70 and 100%, respectively. The 96h-$LC_{50}$(median lethal concentration, $LC_{50}$) of fish to several ${NO_2}^-$ concentrations at pH levels of $6.18{\pm}0.54$, $6.5{\pm}0.30$ and $7.07{\pm}0.22$ were assessed in these experiments. 96h-$LC_{50}$ at pH levels of $6.18{\pm}0.54$, $6.5{\pm}0.30$ and $7.07{\pm}0.22$ were 32.68, 40.49 and 45.85 mg/L, respectively. It indicated that acute toxicity of ${NO_2}^-$ to juvenile banded catfish increased with low levels of pH and lengthening of exposure time to ${NO_2}^-$. In particular, smaller fish(mean weight $14.5{\pm}0.46g$) were more sensitive to ${NO_2}^-$ than larger fish(mean weight $81.7{\pm}1.42g$; not published). The 96h-$LC_{50}$ of juvenile banded catfish to ${NO_2}^-$ would be primary guideline for water quality management in the intensive culture system such as RAS and BFT.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.74-75
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• 2003

This study was conducted to investigate the effects of several additives(macroalgae, wasabi, and herb) in formulated diets on the growth, body composition, blood chemistry and non-specific immune response of juvenile flounder. Three replicates of juveniles (average weight 8.4 g) in flow-through aquarium system were fed one of six isonitrogenous (45%) and isolipidic (8%) diets containing 5 and 10% Undaria powder, 2% wasabi leaf, 2% wasabi stem, and 0.5% herb (Obosan) for 8 weeks. Survival was not affected by the different dietary additives (P>0.05). The highest weight gain and feed efficiency offish fed the diet containing 0.5% herb were significantly higher than those of fish fed the diets containing 10% Undaria powder (P<0.05). No significant differences were found in contents of moisture, crude protein, lipid and ash of whole body (P>0.05). Fish fed the diet containing 10% Undaria powder showed the highest moisture and the lowest crude lipid contents in the liver. Although hematological parameters (red blood cell, hematocrit and hemoglobin) and serum constituents (glucose, total cholesterol and glutamic-oxaloacetic transaminase) contents of fish varied between treatments, no specific trend was observed throughout feeding periods. Lysozyme activity in the serum and nitroblue tetrazolium reduction of macrophage in the head kidney from fish fed the diets containing herb was significantly higher than those of fish fed the control diet. The results of this study suggest that herb as an additive in this formulated diet may improve growth and non-specific immune response of juvenile flounder.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.3
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• pp.461-467
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• 2011

This experiment was conducted to determine the each level of a newly developed squid liver powder (SLP) as a dietary protein source replacing fish meal (FM) in juvenile flounder. A diet excluding SLP (FM diet) and a commercial diet were two control diets. Six experimental diets were formulated to replace FM with three types of SLP at 5 and 10% level, respectively (SLP-A5, SLP-A10, SLP-B5, SLP-B10, SLP-C5, SLP-C10). Prior to the start of a feeding trial, fish were fed the commercial diet for 1 week to adjust to the experimental conditions. Fish with average weight of $22.8{\pm}0.40g$ ($mean{\pm}SD$), were randomly distributed to each aquarium as groups of 20 fish and fed the experimental diets in triplicate at satiation for 8 weeks. After 8 weeks, weight gain and specific growth rate of fish fed SLP-C10 was lower than those of fish fed FM diet and SLP-B5. Meanwhile, no significant difference was observed in WG and SGR among fish fed diets excluding SLP-C10. Feed efficiency (FE) and protein efficiency ratio (PER) of fish fed each level of three types of SLP were not different from those of fish fed FM diet. However, fish fed SLP-C5 and SLP-C10 has lower FE and PER than those of fish fed a commercial diet, SLP-A5 and SLP-B5. Therefore, these results indicate clearly that dietary SLP-B could be a good protein source to develop inexpensive commercial diet in juvenile flounder.

• Development and Reproduction
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• v.22 no.1
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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.

• Journal of Korean Academy of Nursing
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• v.30 no.1
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• pp.148-159
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• 2000

The purpose of this study was to test the theoretical model designed to explain juvenile delinquency by media violence. Data were collected through questionnaire survey over a period of 3 months. Subjects served for this study consisted of 537 adolescents including 217 delinquent adolescents and 320 student adolescents in Korea, sampled from Korean student population and delinquent adolescent population confined in juvenile correctional institutions, using proportional stratified random sampling method. In this study, exogeneous variable was family dynamic environment and endogeneous variables were character of adolescent including need satisfaction/ frustration, sociability, antisocial personality tendency, complaints of psychosomatic symptoms and depressive trend, juvenile delinquent behavior and media violence themes including the extent of interest in and exposure and modelling impulsiveness and modelling to media violence themes. A total of 18 instruments were used to operationalized concepts in this model. A validation study indicated that internal consistencies for the 18 instruments which the researcher used were reliable. The one month test-retest correlation for these instruments ranged from 0.54 to 0.88. Statistical methods employed were descriptive statistics and covariance structural modelling. In summarized conclusion, it was found that media violence served as the most contributor to juvenile delinquency by direct effect of 0.64(t=10.18). That is, as the adolescents have to be the higher extent of interest in and exposure and modelling impulsiveness and modelling to media violence themes, they will show the more frequency of delinquent behavior. The single most powerful contributor by total effect of 0.73(t=7.90) (direct effect=0.19, indirect effect=0.54) to the development of delinquent behavior identified in this study was a construct defining family dynamic environment. That is, as the adolescents had to be more unstable family dynamic environment, they became more frustrated to their psychological need, and revealed the more maladaptive personality pattern, consequently they behaved the higher misconducts such as juvenile delinquency through media violence.

• Development and Reproduction
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• v.24 no.1
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• pp.63-70
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• 2020

This study aimed to investigate early life of Coreoperca herzi living in Han River and compare morphological differences between different groups during the development in order to provide basic data for relevant taxonomic research. On average, one female individual spawned 541 to 861 eggs (average 701) at once. After 259 hours, the tail broke out of the egg membrane and hatching began. Immediately after hatching, the larvae were average 7.81±0.10 mm (n=5) in total length. 60 days the juvenile was average 35.9±1.30 mm (n=5) in total length. The white spots spread to the rest of the body, rending the same pattern as that on the body of their broodstock fish.

• Development and Reproduction
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• v.21 no.1
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• pp.63-69
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• 2017

On the 15 days after hatching, the larvae was 4.24-5.10 mm (mean $4.66{\pm}2.18mm$) in total length, and the fins of the membrane started to develop into a fan shape and the melanophore was deposited upper the alimentary canal of the abdomen and on the bladder. At 35 days after hatching, the post-larvae formed a branch-shaped melanophore on the head part with a total length of 6.98-12.5 (mean $9.35{\pm}1.71$) mm, formed on the upper and lower parts of the caudal part, formed on the upper and lower parts of the caudal part, and deposited under the head part and abdomen. At 40 days after hatching, the juvenile was 11.3-18.1 (mean $14.9{\pm}1.53$) mm in total length.

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.475-476
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• 2004

• Review of Korea Contents Association
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• v.17 no.3
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• pp.26-32
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• 2019

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.500-504
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• 2013

A total of 24 juvenile specimens of Thunnus tonggol (5.45~7.26mm in total length) of the Sombridae were collected from the southeast sea of Jeju Island during 26~30 July, 2013. Twenty-four specimens identified T. tonggol have melanophores distributed on the 1st dorsal-fin rays, the dorsal of head and vetral side. Three individulas were identified using mitochondrial DNA cytochrome oxidase submit 1 (CO1) sequences (452 base pairs). All were identified as T. tonggol, their mtCO1 sequences being consistent with those of Thunnus tonggol (d=0.000), followed by Thunnus albacares (d=0.002) and Thunnus obesus (d=0.007).