• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.600-603
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• 2009

Genetic and phenotypic parameter estimates for measurement traits were obtained from pacific oyster Crassostrea gigas at nine months old. For the growth-related traits among nine months old pacific oyster, heritabilities of shell length, shell height, shell width, total weight, body weight and shell weight were estimated as 0.4855, 0.5248, 0.0884, 0.7236, 0.7726 and 0.6957, respectively. Genetic correlations among the growth-related traits of pacific oyster at nines month old, shell length, shell height, shell width, total weight, body weight, shell weight were showing highly positive correlations. Breeding value on growth-related traits of pacific oyster at nine months old were estimated as shell length -7.044-11.870, shell height -11.380-18.370, shell width -1.234-2.831, total weight -8.339-17.140, body weight -1.813-3.507 and shell weight -4.422-8.837. The results show that there is quite substantial additive genetic variance for measurement traits in pacific oyster that can be exploited through selective breeding.

• Journal of Aquaculture
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• v.21 no.4
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• pp.265-271
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• 2008

Upper temperature tolerance of the turbot Scophthalmus maxim us, one of the popular aquaculture species in European community and China, was evaluated in terms of survival and growth at $20^{\circ}C$, $23^{\circ}C$, $26^{\circ}C$, or $29^{\circ}C$. Best growth was achieved at temperature $20^{\circ}C$ in this experiments. The fish exposed to $20^{\circ}C$ or $23^{\circ}C$ were comparable in survival, condition factor and feed conversion efficiency reminiscent of the latter temperature to be agreeable for the fish. The temperature over $23^{\circ}C$ appeared to be the temperatures beyond the fish can tolerate. For instance, the fish exposed to 26 showed mortality of 60.9% by day 60; none of the fish exposed to $29^{\circ}C$ survived beyond day 7. Culture densities between 80 and $200\;fish/m^2$ did not influence the survival, growth, condition factor and specific growth rate of the fish. The final production of the culture density experiment was $10\;kg/m^2$ on average. These results imply that the location where water temperature remains lower than $25^{\circ}C$ during summer can be a candidate site for the turbot aquaculture.

• Journal of fish pathology
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• v.20 no.2
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• pp.99-108
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• 2007

Vibrio harveyi, one of the major causal agent of vibriosis, affects a diverse range of marine vertebrates and invertebrates over a wide geographical area. The organism is synonymous with Vibrio carchariae, which is also known as a fish pathogen. The aims of this study were to investigate the characteristics of the pathogenic non-luminous V. harveyi and the luminous V. harveyi. And V. harveyi isolates were examined the pathogenicity to the black rockfish, Sebastes schlegeli. Both strains of V. harveyi showed haemolytic activity, and the survival rate of non-luminous V. harveyi FR 2 was higher than other strains in the skin, gut mucus and fresh serum of olive flounder, Paralichthys olivaceus and black rockfish, Sebastes schlegeli, respectively. The virulence of non-luminous V. harveyi FR 2 was higher than that of luminous V. harveyi VIB 391 in the intraperitoneally infected black rockfish. In conclusion, the present study revealed that the pathogenicity of V. harveyi FR 2 isolated from marine fish was higher than that of V. harveyi VIB 391 isolated from shrimp for black rockfish. It was suggested that the pathogenicity of V. harveyi on the black rockfish was related with bacterial luminescense.

• Journal of Aquaculture
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• v.21 no.4
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• pp.339-345
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• 2008

Farming of the fleshy shrimp Fenneropenaeus chinensis which is a major cultured species in the west coast of South Korea, has been suffered :trom mass mortality due to disease epizootics including viruses. Since the Pacific white shrimp Litopenaeus vannamei was introduced to Korea in 2003, farming of this species has rapidly increased for years, occupying 62.5% of total cultured shrimp production in 2007. However the studies on L. vannamei culture methods for shrimp farming situations in Korea are very limited. Nursery culture of shrimp larvae has some advantages including increased survival, improved feed efficiencies, enhanced growth performance and reduced grow-out period. In this study, L. vannamei postlarvae (${PL_3}-{PL_{10}}$) with a density of $3,750-9,090/m^3$ were cultured in four raceways under limited water exchange condition for 35 days. Survival was the highest (93.6%) in tank stocked with $4,090/m^3$ and was the lowest in tank with $9,090/m^3$ (58.1 %). Mean body weight at harvest ranged from 0.071 to 0.108 g, and FCR was 0.59-0.70 in all tanks. Concentration of total ammonia nitrogen was increased up to 20 ppm on day 10 in all tanks and thereafter gradually decreased by the third week of culture. Nitrite-nitrogen was rapidly increased from the third week, representing bio-floc condition by developed nitrifying bacterial community. Of the present nursery system some modification of structure and consideration for commercial scale are needed in order to be implemented to shrimp farmers.

• The Journal of Fisheries Business Administration
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• v.14 no.2
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• pp.69-109
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• 1983

• Fisheries and Aquatic Sciences
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• v.5 no.2
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• pp.108-113
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• 2002

Apical and subapical fragments of Gracilaria verrucosa (Hudson) Papenfuss (Rhodophyta) were cultured on a temperature-light gradient table with four temperature $(15,\;20,\;25\;and\;30^{\circ}C)$ and five light intensity $(20,\;40,\;60,\;80\; and\;100{\mu}mol\;photons\;m^{-2}s^{-l})$ regimes to examine growth responses. Their growth was measured weekly. Plant weight and lateral branch formation were affected by temperature and light intensity. As compared with other reports, relative growth rate (RGR) in both fragments was more or less high with 6.27 to $11.95\%$ $day^{-1}$. It was lowest at $15^{\circ}C$ with $20\mu mol$ photons $m^{-2}s^{-l}$, whereas, the highest value was recorded at $25^{\circ}C$ with $100\mu mol$ photons $m^{-2}s^{-l}$ During the experimental period, the growth pattern in G. verrucosa was significantly different between apical and subapical fragments, even though RGR based on weight was similar. Growth in apical fragments depended on elongation by apical growth. By contrast, subapical fragments mainly increased their weights by proliferation of lateral branch. This suggests that intercalary activity (e.g. lateral branch formation) is also an important means for growth of the thallus in Korean G. verrucosa. In conclusion, the relatively high growth potential with the intercalary activity in G. verrucosa will be helpful for mariculture in Korea.

• ALGAE
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• v.32 no.4
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• pp.349-357
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• 2017

Korean mariculture Undaria pinnatifida was collected during the months of January, February, March, and December of 2010, as well as from January of 2011 to investigate the changes in the carbon and nitrogen stable isotope ratios (${\delta}^{13}C$ and ${\delta}^{15}N$) and heavy metal with respect to it growth and to identify the factors that influence such changes. The blades of U. pinnatifida showed ${\delta}^{13}C$ and ${\delta}^{15}N$ in the range (mean) of -13.11 to -19.42‰ (-16.93‰) and 2.99 to 7.57‰ (4.71‰), respectively. Among samples with the same grow-out period, those that weighed more tended to have higher ${\delta}^{13}C$ suggesting a close association between the carbon isotope ratio and growth rate of U. pinnatifida. Indeed, we found a very high positive linear correlation between the monthly average ${\delta}^{13}C$ and the absolute growth rate in weight ($r^2=0.89$). Nitrogen isotope ratio tended to be relatively lower when nitrogen content in the blade was higher, probably due to the strengthening of isotope fractionation stemming from plenty of nitrogen in the surrounding environment. In fact, a negative linear correlation was observed with the nitrate concentration in the nearby seawaters ($r^2=0.83$). Concentrations of Cu, Cd, Pb, Cr, Hg, and Fe in the blades showed a rapid decrease in their concentration per unit weight in the more mature U. pinnatifida. Specifically, compared to adult samples, Cu, Hg, and Pb were concentrated by 30, 55, and 73 folds, respectively, in the young blades. Therefore, U. pinnatifida tissue ${\delta}^{13}C$ is as an indirect indicator of its growth rate, while ${\delta}^{15}N$ values and heavy metal concentrations serve as tracers that reflect the environmental characteristics.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.4
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• pp.407-418
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• 2020

Mass mortality of mariculture fish due to high summer temperatures is a major issue in the mariculture industry in many coastal waters of Korea, yet measures to mitigate the impact are generally limited. We injected a micro-bubble of liquefied oxygen into the bottom of rockfish cages (about 6-8 m deep) in order to maximize the dispersal of micro-bubbled seawater and reduce fish mortality. The injection of low-temperature oxygen in micro-bubbles lowered the water temperature at the injection area by as much as 1℃ and increased dissolved oxygen concentration by 0.5 ppm. In early August, following a week with persistent high water temperature (above 28.5℃), there was an increase in fish mortality despite the micro-bubble system, which resulted in approximately 7% death of the total introduced fish population. However, this mortality appeared to be much lower than mortality reported in a neighboring mariculture facility (approximately 50% mortality). We also estimated the volume that can be recirculated with pumped seawater using a micro-bubble system. We suggest that this approach of injecting liquefied oxygen through a micro-bubble system may reduce fish mortality during high temperature periods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.2
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• pp.113-118
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• 2008

Diel rhythm of oxygen consumption (OC) of the starry flounder Platichthys stellatus was measured at different water temperatures in a closed recirculating seawater system with a respiratory chamber. The fish consumed 70.5, 79.7, and 90.6 mg $O_2/kg/hr$ at 15, 20, and $25^{\circ}C$, respectively, showing a linear increase in OC with water temperature. The OC of fish showed a clear diel rhythm, with lower values during the day and higher values at night, in accordance with the light (09:00-21:00) and dark (21:00-09:00) phases of the diel cycle (12L:12D) in water at 15 and $20^{\circ}C$. However, the OC of the fish showed an unclear diel rhythm with the light and dark phases of the diel cycle at $25^{\circ}C$. The respective OC at 15, 20 and $25^{\circ}C$ was 63.8, 72.4, and 88.4 mg $O_2/kg/hr$ during the light phases and 77.2, 87.1, and 92.8 mg $O_2/kg/hr$ during the dark phase. The starry flounder is thought to be a nocturnal fish with a higher OC at night, while it rests during the day. Its OC was the most stable in the light, when it did not feed. Consequently, the night-time OC is the active OC and the day-time OC is the resting OC in the starry flounder.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.105-112
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• 2009

We investigated the degree of obesity, histological development stages of gonads and sexual maturation induction rates of comb pen shell, Atrina pectinata, per the type of micro-algae supplied. Terms of maturation by singular or mixed supply of microalgae, it was found that maturation of the female was the quickest at 60.0% by the Tetraselmis tetrathele (Tet). experiment group followed by 57.1% by the Chlorella ellipsoidea (Chl). experiment group and 16.7% by the Phaeodactylum tricornutum (Pha). experiment group. However, there were no significant differences between Tet. experiment group and Chl. experiment group. As for the male, maturation was the quickest at 60.0% by the Tet. experiment group followed by 16.7% by the Chl. experiment group and 14.3% by the Pha. experiment group. In light of these results, Tet. is concluded to be a very useful feed organism in breeding the mother comb pen shells. Upon completion of the experiment, the sexual maturation induction rate for the female was found to be the highest at 82.0% in the Tet. experiment group followed by 72.0% by the Chl. experiment group, 64.0% by the Pha. experiment group and 58.0% by the mixed micro-algae experiment group. During the period of experiment, the survival rate was the highest at 94.4% by the mixed micro-algae experiment group followed by 90.0% by the Pha. experiment group, 83.1% by the Tet. experiment group and 78.8% by the Chl. experiment group.