• Journal of Aquaculture
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• v.8 no.4
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• pp.271-283
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• 1995

Blue tilapia, Oreochromis aureus (Steindachner) swim-up fry were fed a ration containing 0, 1, 10, or 60 ppm $17\alpha-Methyltestosterone$ (MT) for 30 days (sex reversal period). Fish that had been fed 0 ppm MT-treated feed during the sex reversal period were subsequently fed rations containing either 0 ppm MT, 10 ppm MT, or 60 ppm MT for the next 39 days (post sex reversal period) : fish that had been fed 60 ppm MT-treated feed during the sex reversal period were subsequently fed rations containing either 0 ppm MT, 10 ppm MT, or 60 ppm MT during the post sex reversal period. One group was fed 1 ppm MT-treated feed, while another group was fed 10 ppm MT-treated feed during both periods. The following growing season (10 months later), the residual effects of MT on weight gain, body composition, and gonosomatic indices (GSI) were evaluated. MT had no residual effect on growth of either sex. Groups that ate MT-treated feed were significantly (P<0.05) larger than those that received no MT during the sex reversal period, because females in the latter group lowered average weight gain. MT had a positive residual effect on body fat content in males, but had a negative effect on body moisture content. MT had a positive residual effect on body moisture content in females. MT had a significant negative effect on male and female GSI at the end of the post sex reversal period. MT consumption during the sex reversal period had a significant negative residual effect on male GSI. MT fed after sexual development (post sex reversal period) did not have a residual effect on male or female CSI.

• Journal of Nutrition and Health
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• v.18 no.4
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• pp.259-271
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• 1985

The purpose of this study was to develop supplementary foods for infants and young children in order to improve their nutritional status. Three formulas composed of rice, soybeans, fish, dry skim milk and sesame in varying proportions were studied. The three formulas, $RS_{1}S_{2}$, $RFS_{1}S_{2}$, and $RMS_{1}S_{2}$, were consisted of Rice(R), Soybean$(S_{1})$, Sesame$(S_{2})$ (60 : 35 : 5) , Rice, Fish(F), Soybean, Sesame (60 : 10 : 25 : 5) , and Rice, Dry Skin Milk (M), Soybean, Sesame (60 : 10 : 25 : 5), respectively. A proximate analysis and amino acid determination were made on the developed formulas. In the animal assay, growth rate, PER and FER were evaluated and biochemical analyses were also carried out. A storage test and the cost evaluation were also conducted. The summarized results are as follows : 1) The proximate composition of the three formulas were 7.3-7.4% of moisture, 15.9-21.5% of crude protein, 7.8-9.6% of crude fat and 2.5-2.8% ash. 2) The result of amino acid analysis showed that the 1st limiting amino acids of $RS_{1}S_{2}$ and $RFS_{1}S_{2}$ were lysine (amino acid score, 76.6) and threonine (amino acid score, 93.3), and that of $RMS_{1}S_{2}$ and the commercially prepared formula were sulfur containing amino acids (amino acid score, 82.0 and 54.4). When the contents of the amino acids of the three formulas were compared with mother's milk and cow's milk, the balance of the amino acid of each formula was superior to mother's milk but inferior to cow's milk. 3) In the animal assay, the growth rate of all groups increased gradually during the experimental period. 4) The C- PER, which was corrected on the basis of the casein PER of 2.5 was 2.99, 3.38 and 3.10 in the $RS_{1}S_{2}$, $RFS_{1}S_{2}$ and $RMS_{1}S_{2}$ respectively. The C- PER of $RFS_{1}S_{2}$ and $RMS_{1}S_{2}$ were Significantly (P<.05) higher than that of the casein. 5) The FER of the casein, $RS_{1}S_{2}$, $RFS_{1}S_{2}$, and $RMS_{1}S_{2}$ were 0.37, 0.39, 0.43 and 0.39, respectively. The FER of $RFS_{1}S_{2}$ and $RMS_{1}S_{2}$ were also significantly (P<.05) higher than that of the casein. 6) The concentrations of hematocrit, hemoglobin, total protein and albumin in the serum of the rats of all groups were not significantly different among groups. 7) The storage stability test showed that the total plate count (TPC), the coliforms count and the bacterial spore count in the ingredients were quiet low. However, after 30 and 60 days storage, the count in $RFS_{1}S_{2}$ increased and were higher at room temperature than refrigerated temperature. 8) In the cost evaluation, the cost of the developed formulas was \1,826-2,626 / kg. This was less than that of the commercially prepared formula (\3,300-4,073 / kg) and that of the imported formula (\4,250-8,720 / kg).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.4
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• pp.233-238
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• 1978

Rainbow trout were reared in a stainless steel aquarium from Nov. 11, 1977 to June 12, 1978, and the following results were obtained : 1. The volume of water was about $400\iota$ in a aquarium measuring $1m\;(Length)\times1m\;(Width)\times67cm(Height)$ and water depth 40 cm. Water was supplied for about 16 hours daily at a rate $3\iota/min$ and was drained through the conical settling part in the middle of the aquarium bottom. Filter tank was about $23cm(W)\times23cm(L)\times40cm(D)$ and contained pebbles 30 cm in depth. Water recirculation rate was at)out $1,030\iota/hr$, or 2.6 turn-over per hour. 2. During the first period (77 days), the trout grew from 88.3g to 229g in average, the total weight attaining 30.7kg. The food coefficient was 1.249, average daily increment 243.3g, average daily growth rate 1.245%, and the mortality was 2 smallest fish weighing 53 g, owing to unknown reason. During the second period (135 days), the trout grew from 239g to 555g in average, the total weight attaining 57.2 kg. The food coefficient was 1.447, average daily increment 279.8g, average daily growth rate $0.65\%$ and the mortality was 31 fish weighing 11,255 g, owing partly to miss-handling and partly to disease. 3. The feed consisting of fully domestic materials was prepared in this laboratory, and the feed conversion was not inferior to high protein commercial feed available in foreign countries. 4. The result of whole period for 212 days was 56.5 kg in gross increment, and based on this result, when $1\iota/min$ full day inflowing water available, the net production will become 28.25 kg. So, if a 5000kg production is planned, $180\iota/min$ or about $10.8m^3/hr$ be reauired, and the production in value frill become 15million won at local price at the expense of about 5.3 million won. From the result of this experiment, rainbow trout is feasible for commercial production in Korea with relatively small amount of well water and simplified water recirculation system.

• Journal of Aquaculture
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• v.4 no.2
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• pp.73-84
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• 1991

Underground sea water is widely utilized for land based aquaculture in Cheju province, Korea nowadays. Salinity of this water($20{\~}30$ ppt) is slightly lower than natural sea water but because of its good water quality and temperature which is maintained at $16{\~}18^{\circ}C$ all year-round, many fish farmers are using this water for finfish culture. To evaluate the possibility of utilizing underground sea water for the seed production of the flounder, Paralichthys olivaeceus, hatching rate of fertilized eggs, survival rate of hatched larvae, and growth rate of the juveniles were tested with various salinity levels ranged from 14.1 ppt to 40.2 ppt. The salinity ranges which showed over $70{\%}$ survival rate for fertilized eggs to hatchout were 33.7 ppt${\~}$40.2 ppt, for hatched larvae to 2-day-old were 20.6 ppt${\~}$40.2 ppt, from 10-day-old to 12-day-old were 27.2 ppt${\~}$40.2 ppt, and from 45-day-old to 47-day-old were 20.6 ppt${\~}$40.2 ppt. Two hundred day old fingerlings showed no mortality when exposured to 7.6 ppt${\~}$40.2 ppt for 2 days. All fish died within 3 days when 45-day-old juveniles were transferred directly from normal sea water to 14.1 ppt sea water. However, they were all survived when transferred first to 20.6 ppt for 3 days then to 14.1 ppt sea water. The highest growth rates of fingerlings reared at 4 different salinities (33.7, 27.0, 31.0, or 15 ppt) were obtained at the 27 ppt group followed by 33.7, 21.0, 15 ppt respectively. The relationship between the days of rearing (X) and the total length of the fingerlings were as follows. $33.7\%$ group : Y=8.8109 + 0.1104X(r=0.999) $27.0{\%}$ group : Y=8.6797 + 0.1208X(r=0.997) $21.0{\%}$ group : Y=8.4081 + 0.1052X(r=0.990) $15.0{\%}$ group : Y=8.4309+ 0.0995X(r=0.990)

• Korean Journal of Environmental Biology
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• v.23 no.3 s.59
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• pp.293-303
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• 2005

Japanese medaka, Oryzias latipes is widely distributed in the North East Asia including Korea, Japan and east China, and commonly used for freshwater toxicity tests and cytotoxicological studies worldwide. In this study, a series of experiments were conducted to identify the potential of the fish as a standard test species for saltwater toxicity evaluation such as marine receiving waters, ocean-dumped materials and sediment pore waters etc. Hatching, growth and mortality rates of the fish were estimated with the wide ranges of salinity from freshwater to seawater (35 psu). Direct exposure of the fertilized eggs in freshwater to the wide ranges of salinity (from 0 to 35 psu) without pre- acclimation to the saltwater revealed no significant differences in hatching rates by salinities (p =0.24). On the other hand, medaka larvae hatched in freshwater and exposed to saltwater directly showed high mortality at > 25 psu treatment groups (p < 0.0001). However, there was no significant difference in mortality of medaka larvae hatched in 13.8 and 14.2 psu at the wide ranges of salinities ($0\~35$ psu). Growth rates of medaka larvae hatched in the above two salinities showed no differences in body length either from 0 to 35 psu treatment groups (p =0.64 for 13.8 psu group and p=0.32 for 14.2 psu group). The number of gill chloride cell in medaka larvae sharply increased when the larvae were exposed to high salinity. Reference tests with zinc chloride revealed 96h $LC_{50}=8.84(7.19\~10.87)mg\;L^{-1}$ using 7~10 day old medaka larvae. These were comparable or better sensitivity in comparison with the other standard test species such as North American sheepshead minnow Cyprinodon variegatus. Based on the results of these experiments, hatching rates and larvalmortality of medaka must be good toxicity parameters for seawater bioassay and the species seems to be a good standard species for both the freshwater and seawater toxicity test.

• Journal of Aquaculture
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• v.11 no.4
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• pp.449-455
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• 1998

The small size food organism(under the size 150${\mu}m$) is needed as food for early stage of marine fish larvae of small mouse (e.g the group of grouper). This study was investigated to develop a method for copepod Apocyclops sp. culture in combination with the rotifer B. rachionus for stable culture of copepod species and harvest of various size food organisms. The culture conditions as temperature, salinity, culture volume, photo period, culture preiod and observation interval were 25${\circ}C$, 22ppt, 40ml, all dark except to observation time, 16 days and every two day during the experimental period, respectively. The Tetraselmis suecica was used as the food for the two testing orgtanisms. After every two day counting, theses two organisms were transferred to fresh culture tanks with Tetraselmis suecica of $7{\times}10^5$cells/ml. In the mixed culture of B. rotundiformis and A. sp., growth of rotifer was suppressed by mixed culture with A. sp. whereas the growth of copepod Apocyclops was promoted in the mixed culture with rotifer B. rotundiformis (the maximum density was 22 individuals/ml through the 16 culture days). Moreover, the number of copepod nauplius were promoted about 2 times in the mixed culture compared to the numbers in single species culture. With this combination culture, the havested two food organisms of variable sizes. This size variation of food organisms was useful tools for larval rearing of small mouse marine fish larvae and next step food organism size of post hatched larvae.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.165-170
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• 2013

In this study, physico-chemical properties and environmental fate were investigated and ecotoxicity tests using fish, daphnia and algae were conducted for an initial ecological risk assessment of 1,2-Benzisothiazol-3-one. Due to low volatility of the test substance under environmental conditions, it is likely to distributed in soil and water environment. The compound has low adsorption in the soil, with low bioconcentration potential. Acute toxicity results showed that 96 h-$LC_{50}$ for Oryzias laties was 4.7 mg/L (measured) and 48h-$EC_{50}$ for Daphnia magna was 3.3 mg/L (measured). In a growth inhibition test with Pseudokirchneriella subcapitata, 72 h-$EC_{50}$ was 0.456 mg/L (growth rate, nominal) and 0.262 mg/L (yield, nominal). Using the acute toxicity value of algae, predicted no-effect concentration (PNEC) in the aquatic environment was determined to be 2.62 ${\mu}g/L$ using an factor of 100. According to globally harmonized system (GHS), the compound was categorized as aquatic acute 1 for algae, while it was categorized as aquatic acute 2 for fish and daphnia. This screening assessment suggests that the test substance may pose ecological risks in the aquatic environment.

• Journal of Aquaculture
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• v.17 no.4
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• pp.275-281
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• 2004

The present study was conducted to evaluate dietary requirements for essential fatty acids (EFAs) such as linoleic acid (LA, l8:2n-6), -lenolenic acid (LNA, 18:3n-3), or docosahexaenoic acid (DHA, 22:6n-3), eicosapentaenoic acid (EPA, 20:5n-3) and arachidonic acid (ARA, 20:4n-6) in juvenile eel Anguilla japonica cultured in a recirculating system for 16 weeks. The experimental diets contained 50% crude protein, 10% crude lipid and 3800 kcal/kg energy.Brown fish meal and blood meal were used as the main protein sources, while coconut oil, com oil and linseed oil were used as the lipid source to yield target fatty acids ratios. At the end of the trial, the effects of essential fatty acids supplementation on weight gain (WG), specific growth rate (SGR), feeding efficiency (FE), proximate composition andwhole body fatty acids contents were examined. WG, SGR, and FEof eels fed diet D2, D3, was significantly higher (P<0.05) than those of fish fed the other diets. Whole body HUFA concentration of eels fed D 1 was significantly lower (P<0.05) than those fed the other diets. HUFA/SFA (saturated fatty acids) ratio of whole body in eels fed diets D2, D3 and D6 were significantly higher than that of eels fed diet D1 (P<0.05).DHA/EPA ratio of whole body in eels fed diet D7was significantly higher than those fed the other diets; and eels fed diet D5 showed the lowest DHA/EPA ratio among all the dietary treatments (P<0.05).Based on the experimental results, we concluded that LNA (n-3) and LA (n-6) were necessary for optimum growth of juvenile eel, and the dietary requirement of LNA and LA were 0.35∼0.5% and 0.5∼0.65%, respectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.2
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• pp.19-30
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• 2019

Objective of this study was to develop an organic fertilizer utilizing domestic livestock horn meal and to investigate the application effect of rice and eggplant. The possibility of utilization of livestock horn meal as an organic resource to replace imported expeller cake fertilizer was examined. In order to select domestic organic resources with high nitrogen content, 8 kinds of organic matter such as chicken manure, fish meal, soybean meal, sesame meal, perilla meal, blood meal, livestock horn meal, and beer sludge were analyzed and organic resources with high nitrogen content were selected. In addition, the conditions for the production of organic fertilizers that can be used in organic agriculture were established by mixing of the rice husk biochar and the rice bran as the supplements with the raw materials for mixing ratios. The content of total nitrogen (T-N) in the livestock horn meal was 12.0 %, which was the next low in 13.5 % blood meal. The content of total nitrogen was 5.9 ~ 7.9 % in fish meal and oil cakes. Total nitrogen content of non-antibiotic chicken manure for organic farming was 3 % and nitrogen content in beer sludge was 3.5 %. Organic fertilizer was produced by using biochar, rice bran as a main ingredient of non-antibiotic chicken manure, livestock horn meal and beer sludge. Compared to nitrogen content (4.0 to 4.2 %) of imported expeller cake fertilizer (ECF), the nitrogen content of organic fertilizer utilizing domestic livestock horn meal is as high as 7.5 %. The developed organic fertilizer is met as Zn 400 mg/kg, Cu 120 mg/kg the quality of organic agricultural materials such as or less. To investigate the effect of fertilizer application on the crops, prototypes of developed organic fertilizer were used for the experiment under selected conditions. As a result of application the developed organic livestock horn meal fertilizer (LHMF) for cultivation of the rice and eggplant, the application quantity of the developed organic LHMF 100 % was decreased by 40 % compared to that of the mixed expeller cake fertilizer (MECF). The application of LHMF, which refers to the application rate corresponding to the nitrogen fertilization recommended by the soil test, was reduced by 40% compared to the application rate of MECF, but the same results were obtained in crop growth and yield. The selection of a new high concentration nitrogen source utilizing domestic organic resources and the development of organic fertilizer is the starting point of the research for substitution of imported ECF using domestic local resources at the present time that the spread of eco-friendly agriculture is becoming increasingly important. If it is expanded in the future, it is expected to contribute to the stable production of eco-friendly agricultural products.

• Journal of fish pathology
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• v.36 no.2
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• pp.263-275
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• 2023

Chum salmon (Oncorhynchus keta) is a species which returns to Korea for spawning and was produced as seed production at the Fisheries Resources Agency located in Uljin-gun, Gyeongsangbuk-do to preserve the species. However, farmed chum salmon showed symptoms of bacterial infection. Therefore, in this study, bacteria were isolated to identify the causative agent from chum salmon in October 2021. The isolated bacteria were identified based on the sequences of 16S rDNA, rpoD (RNA polymerase sigma factor σ⁷⁰), and vapA (A-layer) genes. Also, salinity-growth curve, biochemical characterization, antibiotic susceptibility test, and pathogenicity analysis were performed in four strains. As a result, four isolated strains were identified as Aeromonas salmonicida subsp. salmonicida. Additionally, the bacterial strains showed a decrease in growth as the salt concentration increased in the medium. All of the isolated strains exhibited γ-hemolysis, and the same biochemical properties. In the antimicrobial susceptibility test, all strains showed an inhibition zone of 40 to 44 mm for oxolinic acid, flumequine, and florfenicol. Pathogenic factors were assessed by RT-PCR at the mRNA level, and found that the four strains expresses the outer membrane ring of T3SS (ascV), inner membrane ring of T3SS (ascC), vapA, enterotoxin (act), and lipase (lip) genes which are well known to significantly contribute to the pathogenicity of A. salmonicida. The results of this study can be used as basic data to prevent A. salmonicida subsp. salmonicida occurring in sea-chum salmon in the future.