• Journal of Aquaculture
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• v.17 no.1
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• pp.69-80
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• 2004

The objective of the present study was to analyze genetic distances, variation and characteristics of individuals in rainbow trout, Oncorhynchus mykis using amplified fragment length polymorphism (AFLP) method as molecular genetic technique, to detect AFLP band patterns as genetic markers, and to compare the efficiency of agarosegel electrophoresis (AGE) and polyacrylamide gel electrophoresis (PAGE), respectively. Using 9 primer combinations, a total of 141 AFLP bands were produced, 108 bands (82.4%) of which were polymorphic in AGE. In PAGE, a total of 288 bands were detected, and 220 bands (76.4%) were polymorphic. The AFLP fingerprints of AGE were different from those of PAGE. Separation of the fragments with low molecular weight and genetic polymorphisms revealed a distinct pattern in the two gel systems. In the present study, the average bandsharing values of the individuals between two populations apart from the geographic sites in Kangwon-do ranged from 0.084 to 0.738 of AGE and PAGE. The bandsharing values between individuals No.9 and No. 10 showed the highest level within population, whereas the bandsharing values between individuals No.5 and No.7 showed the lowest level. As calculated by bandsharing analysis, an average of genetic difference (mean$\pm$SD) of individuals was approximately 0.590$\pm$0.125 in this population. In AGE, the single linkage dendrogram resulted from two primers (M11+H11 and M13+H11), indicating six genetic groupings composed of group 1 (No.9 and 10), group 2 (No. 1, 4, 5, 7, 10, 11, 16 and 17), group 3 (No. 2, 3, 6, 8, 12, 15 and 16), group 4 (No.9, 14 and 17), group 5 (No. 13, 19, 20 and 21) and group 6 (No. 23). In AGE, the genetic distances among individuals of between-population ranged from 0.108 to 0.392. In AGE, the shortest genetic distance (0.108) displaying significant molecular differences was between individuals No.9 and No. 10. Especially, the genetic distance between individuals No. 23 and the remnants among individuals within population was highest (0.392). Additionally, in the cluster analysis using the PAGE data, the single linkage dendrogram resulted from two primers (M12+H13 and M11+H13), indicating seven genetic groupings composed of group 1 (No. 15), group 2 (No. 14), group 3 (No. 11 and 12), group 4 (No.5, 6, 7, 8, 10 and 13), group 5 (No.1, 2, 3 and 4), group 6 (No.9) and group 7 (No. 16). By comparison with the individuals in PAGE, genetic distance between No. 10 and No. 7 showed the shortest value (0.071), also between No. 16 and No. 14 showed the highest value (0.242). As with the PAGE analysis, genetic differences were certainly apparent with 13 of 16 individuals showing greater than 80% AFLP-based similarity to their closest neighbor. The three individuals (No. 14, No. 15 and No. 16) of rainbow trout between two populations apart from the geographic sites in Kangwon-do formed distinct genetic distances as compared with other individuals. These results indicated that AFLP markers of this fish could be used as genetic information such as species identification, genetic relationship or analysis of genome structure, and selection aids for genetic improvement of economically important traits in fish species.

• Journal of Aquaculture
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• v.17 no.1
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• pp.39-45
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• 2004

Three experiments were conducted to determine utilization of Song-Gang(equation omitted) stone as the dietary additive for growth and immune stimulant in juvenile olive flounder. In the feeding trial, four diets were formulated to contain 0, 0.5, 1.0 and 2.0% Song-Gang(equation omitted) stone per kg diet (SGS$_{0}$ , SGS$_{0.5}$, SGS$_{1.0}$ , SGS$_{2.0}$ ). Fish averaging 5.0$\pm$0.04 g (mean$\pm$SD) were fed one of four experimental diets in triplicate groups for 8 weeks. There were no significant differences in weight gain, feed efficiency, protein efficiency ratio, hematosomatic index, condition factor and survival among fish fed all the diets. In chanlenge test, fish were infected by intraperitoneal injection of 0.1 $m\ell$ bacterial suspension with Edwardsielia tarda per fish after the feeding trial. Fish fed SGS$_{0.5}$ diet have a significantly higher cumulative survival rate than did fish fed the other diets (P<0.05). In the anti-mold test, Asprrgiilus niger, Penicillium pinophiltfm, Chaeromium globosum were inoculated with Song-Gang(equation omitted) stone using ASTM G-21 method. The amount of Α. niger, Ρ. pinuphiium. C. globosum didn't increase in Song-Gang(equation omitted) stone for 4 weeks for the test period. Therefore, these results indicate that 0.5% Song-Gang(equation omitted) stone per kg diet could increase immune resistance in juvenile olive flounder and Song-Gang(equation omitted) stone could be used as the anti-mold additive in fish feed.

• Journal of Aquaculture
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• v.5 no.1
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• pp.69-79
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• 1992

The muscle extracts of the ascidian, Halocynthia roretzi cultured for two and three years old on the southern coast near Chungmu and the eastern coast near Pohang of Korea, were analyzed for extractive nitrogen (EN), free amino acids (FAA), combined amino acids (CAA), nucleotides and related compounds (NRC), quaternary ammonium bases and guanidino compounds using specimens collected in February 1989 and in April 1989, and compared for those contents with each other. As for the amount of EN, no remarkable difference was found between two- and three-year-old samples collected at St. 1 in the spring and winter seasons, while at St. 2 in the spring season the two-year-old sample was distinctly lower than the three-year-old one. Taurine, proline, glutamic acid, glycine and alanine were the major FAA in every sample. The amount of taurine, the most prominent FAA, was higher in three-year-old sample than in two-year-old one regardless of sampling station and season. Most of the other major FAA showed a similar tendency to EN at both sampling stations in both seasons. Adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP), inosine 5'-monophosphate (IMP), inosine (Ino) and hypoxanthine (Hyp) were detected in all the samples and ATP, ADP and AMP were the major ingredients. The amounts of total NRC were in parallel with those of EN and total FAA. As for the contents of betaines, two- and three-year-old samples collected in the winter season exhibited a great discrepancy each other, the former being clearly lower than the latter, but no remarkable difference was observed between two samples of two groups in the spring season. In proximate composition of the muscles, the two-year-old sample was considerably higher in moisture content and lower in protein and glycogen contents than the three-year-old one at St. 2 in the spring season. The large discrepancies observed between two- and three-year-old samples from St. 2 seems to be attributable to the difference in size of samples rather than to the difference in age.

• Journal of Aquaculture
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• v.11 no.2
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• pp.193-201
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• 1998

This study was carried out to investigate the enviromental quality and the growth of transplanted pen shell, Atrinna pectinata japonica. Followings are the results of growth of transplanted pen shell with respect to the shell size groups from the natural habitat (Usando) in May 1995, and cultivated upto November in the transplantated area (Soomoonri). The water depth of transplantated area andnatural habitat were 3m, 20~25m, respectively. The seawater temperature of the two culturing farms were ranged of 10.9~$27.8^{\circ}C.$, 8.5~$30.0^{\circ}C.$, respectively at the lowest in November adn the highest in July. The seawater salinity of the two areas were ranged of 29.54~35.26$^0\prime\infty$, 28.75~36.31$^0\prime\infty$, respectively at the lowest in July and the highest in November. The phosphoric acid ($PO_4$-P) of the two areas were 0.09~$1.14 ^{\mu}$g-at/l, 0.23~$1.33 ^{\mu}$g-at/l, respectively at the lowest in June and the highest in September. The bottom type of the two areas was a silty mud, 85.23% (82.17~87.26%) in natural habitat and 92.12% (90.76~92.94$^0\prime\infty$) in transplanted area. In this study area, phytoplankton were composed of 19 species. Of these 19 species, Skeletonema costatum was dominant species in seawater between natural habitat and transplantatied area, and 157 cells/ml, 165 cells/ml at August respectively. Stock of phytoplankton in transplantated area were more than those of natural habitat except June and November. The growth of shell length, shell height, total weight, soft part weight and posterior adductor muscle weight of pen shell on different size groups (SL 10, 10~15, 15~20, 20cm) were excellent in shell length of 10cm group, and 99.32%, 107.66%, 871.09%, 951.26% and 1,223.76%, respectively. The survival rate of pen shell was 98.10% in the shell length of 10cm groups, 90.35~94.76% in the others groups. The growth of shell length, total weight, soft part weight and posterior adductor muscle weight of pen shell in transplantated area were more 1.3, 2.6, 2.7 and 4.5 times than those of natural habitat.

• Journal of Aquaculture
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• v.18 no.3
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• pp.160-166
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• 2005

Two feeding trials were carried out to investigate apparent nutrient digestibility of flounder fed experimental diets containing different levels of macro-nutrients by satiation feeding rate (Exp-1) and feeding frequency (Exp-2). Triplicate groups of fish averaging 280 g were fed three experimental diets which contained different levels of carbohydrate, protein and lipid by two feeding regimes (satiation and 80% satiation) and four feeding frequencies (three meals a day, two meals a day, one meal a day and one meal every two days). Feces were collected using a fecal collection column attached to fish rearing tanks for 6 weeks. Apparent digestibilities of dry matter, protein, lipid, energy and carbohydrate were not affected by feeding satiation rate in Exp-1. Apparent protein digestibility was not affected by feeding frequency, whereas affected by dietary composition in Exp-2. Apparent protein digestibility of fish fed a high-protein diet showed a tendency to become higher compared to that of fish fed high-carbohydrate diet and high-lipid diet at the same feeding frequency. Apparent lipid digestibility was not affected by dietary composition, however, affected by feeding frequency. Apparent digestibilities of energy and carbohydrate were affected by both dietary composition and feeding frequency. Apparent digestibities of energy and carbohydrate in fish fed the high-protein diet showed a tendency to become higher compared to that of fish fed the high-carbohydrate diet and high-lipid diet at the same feeding frequency. Apparent digestibities of energy and carbohydrate tended to decrease with increasing of feeding frequency at the same dietary composition.

• Journal of Aquaculture
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• v.11 no.2
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• pp.213-221
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• 1998

The effects of differen concentrations of Obosan as a feed additive dietary herb were examined on survival rate, growth, feed conversion ration and condition factor in olive flounder (paralichthys olivaceus). Effectiveness of dietary Obosan with optimized concentration for 48 weeks were also observed with regard to growth performances and yields. All groups fed diets containing 0.15, 0.3 and 0.6% of Obosan revealed significantly higher survival rate than control group (P<0.05). Growth, feed conversion ratio and condition factor of olive flounder fed diets containing Obosan were considerably improved when compared to those of controls (P<0.05). The 0.3% of dietary Obosan was proven to be the optimal concentration in all parameters tested. The dietary Obosan (0.3%) for 48 weeks showed significantly higher surval rate than control (P<0.05), and also improved yields in weight gain (19.0% improvement), specific growth rate (4.8%), feed conversion ratio(13.6%) and condition factor (10.8%), significantly (P<0.05).

• Korean Journal of Ichthyology
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• v.20 no.3
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• pp.173-178
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• 2008

The substrate preferences of juvenile black sea bass Centropristis striata (Linnaeus) was tested in a circular tank (1.5 m diameter${\times}$0.4 m deep) divided into two equal areas of oyster-related (oyster reef and whole oyster shell) and sand substrates. All trials were video taped for 20 min. Tapes were viewed on a monitor and locations of all fish recorded and timed with respect to substrate. $Mean{\pm}SE$ times on oyster shell were $18.1{\pm}2.0min$ (1-fish trial-1) and $17.5{\pm}1.7min$ (5-fish trial-1). $Mean{\pm}SE$ times on sand were $2.0{\pm}1.0min$ (1-fish trial-1) and $2.5{\pm}1.7min$ (5-fish trial-1). Black sea bass juveniles showed a significant preference for oyster reef and shell over sand substrate in single-fish trials (paired t-test, P<0.05) and also in five-fish trials (paired t-test, P<0.05). $Mean{\pm}SE$ times under oyster reefs were $16.6{\pm}2.0min$ in single-fish trials and $10.7{\pm}2.3min$ in five-fish trials. Mean numbers of movements among oyster reefs were $1.1{\pm}1.0$ in single-fish trials and $11.5{\pm}3.1$ in fivefish trials. Fish spent significantly less time under oyster reefs in five-fish trials, compared to single-fish trials (paired t-test, P<0.05) and they moved more frequently in five-fish trials than in single-fish trials (paired t-test, P<0.05). Significantly higher competition for a refuge in five-fish trials may induce less time under oyster reefs as well as frequent movement of black sea bass juveniles on shell substrate.

• Journal of Aquaculture
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• v.17 no.2
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• pp.144-150
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• 2004

This experiment was conducted to evaluate the parameters such as nutrient requirements, POY, AnV, Totox, VBN, total plate count, dietary fatty acids and amino acids composition, that are not included in the registered standard composition items required by the Ministry of Agriculture and Forestry, of a moist pellet (MP), three domestic extruded pellets (DEP-1, DEP-2, DEP-3), and two foreign extruded pellets (FEP-1, FEP-2) that are utilized by domestic flounder farms at present. The crude protein was added in excess of the dietary protein requirement in 6 kinds of feeds. When considering the proper PH ratio, it is obvious that protein was added in excess, especially in MP and FEP-2. Crude fat was also added in excess, especially in FEP-1. MP contained a higher dietary phosphorus content than formulated feeds, surpassing the dietary phosphorus requirement and greatly increasing the possibility for causing water pollution. The oxidation of fatty acid and decomposition of protein in MP were higher than in formulated feeds, and may also cause problems on fish farms. Also, it is difficult to store and manage MP, Among the fatty acids, EPA and DHA contents in MP were higher than those in formulated feeds. It is necessary to conduct further studies of EPA and DHA contents in formulated feeds. Lysine content in MP and FEP-2 could meet the dietary lysine requirement of flounder, however, the possibility of insufficient lysine content in the other formulated feeds was high and we considered that extra supplementation was necessary. Therefore, it is necessary to set up quality control standards according to fish species and sizes while considering the specific character of aquatic formulated feeds to restore the confidence of feed companies and aquaculturists to these feeds. This may be an opportunity to make an earlier change from MP to formulated feeds.

• Journal of Aquaculture
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• v.17 no.3
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• pp.187-196
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• 2004

This study was carried out to investigate changes in biochemical composition of rotifer, Brachionus plicatilis, enriched with the commercial enrichments (Enhance, Advantage, Algamac-2000, DHA-Selco and Advantage ＋ Chlorella) at various durations of enrichment (0, 6, 12 and 24 hr) to improve the growth and survival of marine fish larvae. Total lipid content of rotifers enriched with various enrichments tended to increase with an increase in durations of enrichment up to 6 hr, but after that, was not significantly affected by enrichment materials. However, total protein content of rotifers enriched groups except for Advantage＋Chlorella decreased with the increase in duration of enrichment. The highest protein/lipid ratio showed 2.7 in rotifer enriched with the Advantage ＋Chlorella. The phospholipid/lipid ratio of rotifer enriched with the Enhance, Advantage and Advantage＋Chlorella groups was significantly higher than that of enriched rotifer with the Algamac-2000 and DHA-Selco groups. The highest DHA level, 2.5%, of rotifer enriched for 24 hr was obtained in the Advantage, but was not significantly different among other groups, except for Algamac-2000. No significant difference in DHA level of rotifer enriched with the DHA-Selco, Algamac-2000 and Advantage＋Chlorella groups was observed between l2h and 24hr of enrichment. The DHA/EPA ratio in the enriched rotifers varied among enrichment material groups, ranged from a high level of 11.1：1 in the Advantage＋Chlorella group to a low level of 4.1：1 in DHA-Selco group. The results from this study indicate that rotifers enriched with Enhance, Advantage and Advantage＋Chlorella seemed to be effective to improve nutritional value of rotifer for marine fish larvae because phospholipid, DHAJEPA and protein/lipid ratios of rotifer enriched with Enhance, Advantage＋Chlorella were higher than those of rotifer enriched with either DHA-Selco or Algamac-2000. Especially, supplementation of the Chlorella to these enrichments would appear to be effective for improvement of fish larval performance because of no reduction of protein level in rotifer, which is critical for growth of fish larvae.

• Journal of Aquaculture
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• v.11 no.1
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• pp.11-17
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• 1998

Variations of hepatocyte in the larval liver of grouper, Epinephelus akaara wre examined to understand the effect of starvation during the first feeding period, 3 to 5 days after hatching. Total length of the fed larvae increased from the 5th day after hatching, although no significant difference between the fed and starved larvae was found untill the 4th day after hatching. Survival rate of the starved larvae decreased from the 4th day after hatching, and almost all of the larvae died by the 5th day after hatching. Nuclear size of hepatocyte in the starved larvae starterd to decrease from the 4th day after hatching. The sizes by 4th and 5th days after hatching in the starved larvae were 1.4 to 1.9 times smaller than those in the fed ones. Hepatocytes in the starved larvae showed irregular morphology in which the nuclei were irregularly shrunk and highly compacted from the 4th day, while hepatocyte nuclei in the fed ones maintained their uniform features during the whole experimental period. These results implied that the initial larval food should be supplied at least within the 4th day after hatching. Also, it suggested that the size of hepatocyte nucleus might be and indicator of starvation for wild and cultured grouper larvae.