• 한국양식학회지
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• 제18권2호
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• pp.69-75
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• 2005

One 30-day feeding trial was conducted to examine the effects of dietary salt on seawater adaptability of rainbow trout (Onchorhynchus mykiss) fed three experimental diets containing 0% (control), 4% and 8% salt. The experimetal period included 30 days of feeding trial in freshwater, 3 days of the step by step seawater acclimation with-out feeding diets, and 21 more days of seawater adaptation period (not with all experimental fish) with feeding the basal diet. Growth rates from triplicate groups were determined fur 30 days of feeding trial. Blood samples were taken at the begining and at the end of feeding trial, and 3 times (on 1st, 4th and 8th day) of the seawater adaptation period. Daily survival rates of duplicate groups from three experimetal treatments were recorded for 21 days of the seawater adaptation period. Total average initial and final fish weight were $149.5{\pm}7.6\;and\;187.1{\pm}7.6g$. Feed efficiency of fish fed diets containing 4% and 8% salt were significantly better than those of fish fed the control diet. Average cumulative survival rates were 72, 80 and 88% from the control, 4% and 8% salt diets, respectively. Pulse rate per minutes decreased with dietary salt level. Serum $Na^+\;and\;Cl^-$ concentrations of fish fed 4% and 8% salt diets were significantly higher than those of fish fed the control diet (P<0.05), however, the concentrations were stabilized after 8 days of seawater adaptation. Serum cortisol, glucose, cholesterol and tryglyceride concentrations, and the osmorality of fish decreased with dietary salt level, these values were significantly lower than those of fish fed the control diet. These results indicated that the dietary supplementation of salt could have advantages for seawater adaptability of rainbow trout.

• 한국수산과학회지
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• 제46권5호
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• pp.534-539
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• 2013

To secure the biological safety of live fish and shellfish for raw consumption, the germicidal effects of electrolyzed seawater were evaluated. Upon direct exposure to electrolyzed seawater, coliform group bacteria were killed and decreased to undetectable levels after 1 day. The physicochemical characteristics of the seawater were stable during the test period. A byproduct of chlorine disinfection, trihalomethane, was not generated by the electrolysis of seawater. Vibrio parahaemolyticus infection in a live fish was effectively resolved by electrolyzed seawater and became undetectable after 12-36 h of treatment. Bioaccumulation of coliform group and fecal coliform bacteria in live oysters Crassostrea gigas was removed within 18 h of treatment. This study demonstrated that electrolyzed seawater is an effective and safe germicidal agent for the traditional retail market and can help to prevent outbreaks of foodborne disease associated with the consumption of raw fish and shellfish.

• 한국어병학회지
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• 제33권1호
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• pp.91-95
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• 2020

Fish bacterial diseases have spread and caused serious problem for cultured marine fish in Korea. The important bacterial disease affecting mariculture such as olive flounder (Paralichthys olivaceus) are caused by Edwardsiella tarda, Vibrio scophthalmi and Streptococcus parauberis. For the bacterial disease protection in aquaculture industry, the water treatment is needed in aquaculture system. During the last decades atmospheric pressure non-thermal plasma in contact with liquids have received a lot of attention of environmental and medical application. In this study, we determined the disinfectant effect in seawater and three major fish bacterial disease pathogens by using low frequency plasma treatment. Three fish bacteria (E. tarda, V. schophthalmi, S. parauberis) were not detected within 16 min, 150 min and 270 min of 20 L, 500 L and 1 ton seawater post low frequency plasma treatment, respectively. Three major fish bacterial disease pathogens were not detected within 2 min after the low frequency plasma treatment, suggesting that the low frequency plasma possess disinfectant effectiveness.

• 한국발생생물학회지:발생과생식
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• 제24권3호
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• pp.215-224
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• 2020

Seawater adaptability of steelhead trout increases along with the increase in the size of the fish, independent of parr-smolt transformation. Three 96 h seawater challenge tests were conducted to determine the size at which seawater adaptability of steelhead trout develops. Plasma Na⁺ and Cl^- levels, moisture content, gill Na⁺/K⁺ ATPase activity, and mortality during the 96 h after direct transfer to seawater (32 ppt) were determined. Plasma Na⁺ and Cl^- levels in 50 g fish continuously increased during the 96 h after the transfer to seawater (p<0.05), but the levels in 100 and 150 g fish leveled off after 24 h (p<0.05). Both 100 and 150 g size steelhead trout maintained muscle moisture content (%) better than 50 g size fish (p<0.05). Gill Na⁺/K⁺ ATPase activity in the 100 g size group increased in a time-dependent manner after transfer to seawater (p<0.05), whereas activity in the 50 and 150 g sizes did not increase (p>0.05), for which a possible explanation was discussed. A mere 2.6% mortality in both the 50 and 150 g size groups was observed. In conclusion, the current results indicate that 50 g size steelhead trout did not show development of a high level of hypoosmoregulatory capacity, whereas fish in the 100 and 150 g size groups showed a high level in our experimental conditions. Therefore, the steelhead trout larger than a 100 g size is recommended for transfer to seawater culture.

• 한국동물위생학회지
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• 제22권4호
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• pp.357-361
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• 1999

The most harmful nitrogenous compounds in fish-breeding place using are ammonia and nitrate. Excessively high total nitrogen concentration is the signal of unbalance for breeding fishes in seawater and may result overfeeding or overstocking without seawater treatment system. The failure of elimination for the organic ingredients or nitrogen compounds can also cause the consequence of inadequate oxygen concentration in seawater, either. The study shows the effect of biofilter and W disinfector of seawater in the fish- breeding place. In the results, these tools had ammonia, nitrite, nitrate and decreased 71.8%, 27.6% and 1%, respectively, and the total number of microorganisms decreased up to 81.9%.

• 수산경영론집
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• 제46권1호
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• pp.63-74
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• 2015

Due to red tide and abnormal currents that take place every year, the damage of inland fish farms that takes sea water is increasing frequently. Also, the households of inland fish farm due to the increase in the cost of fuel and electricity are struggling many hardships economically. In relation to underground seawater for it's farm analyzed economic effect based on the actual conditions for 1,700 inland fish farms, from this I have deduced policy implications for direction this project to be pursued from now on. The saving rate of costs of the fuel and electricity through the development of an underground seawater were approximately analyzed to decline about 3.4~9.7%, if utilizing only about 5% of the undeveloped farms, it was estimated effect of about 61 billion won, if 10%, it was estimated effect of about 122 billion won. Consideration in selecting the developer of underground seawater will be selected an character of farm method. It is expected this study will be helpful for business analysis related government in the fisheries.

• 한국수산과학회지
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• 제41권1호
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• pp.20-25
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• 2008

The susceptibility of five different marine fish to iridovirus IVS-1 infection was analyzed and found a higher the cumulative mortality in the order of rock bream (Oplegnathus fasciatus), red sea bream (Pagrus major), sea perch (Lateolabrax sp.), rockfish (Sebastes schlegeli) and black porgy (Acanthopagrus schlegeli). However, the concentrations of virus in the infected spleens of these species did not differ significantly. To determine the release of iridovirus from infected fish into culturing seawater, rock bream were challenged with iridovirus IVS-1 and the concentration of virus in the water was analyzed using PCR. Over the 10 days of the analysis, the linear relationship between the number of dead fish and viral DNA concentration found in culturing seawater should be considered direct evidence of horizontal iridovirus transmission.

• 한국수산과학회지
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• 제31권6호
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• pp.908-913
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• 1998

육상수조를 이용한 해산어의 양식은 사육환경의 악화와 질병발생 등으로 인하여 생산성이 점차 저하되고 있으며, 배출수로 인해 양식장 주변연안의 환경문제점을 유발하고 있다. 따라서, 본 연구는 시스템 및 자동화 설계기술을 이용하여 유입수처리를 위한 스크린필터와 배출수 처리를 위한 드럼필터의 개발을 위한 기초단계로서 각각에 대한 개념 설계를 수행하고, 이를 바탕으로 한 실험용 모델의 제작가 운행을 수행하였다. 그 결과 현장용필터제작에 필요한 초기설계 및 상세설계에 대한 자료를 얻을 수 있었으며, PLC를 이용한 자동화는 장치의 효용성을 향상시킬 수 있었다.

• 한국환경과학회지
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• 제23권3호
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• pp.483-492
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• 2014

DNA damage such as genotoxicity was identified with comet assay, which blood cell of a marine parrot fish (Oplegnathus fasciatus) was exposed to an acidified seawater, lowered pH gradient making of $CO_2$ gas. The gradient of pH were 8.22, 8.03, 7.81, 7.55 with control as HBSS solution with pH 7.4. DNA tail moment of fish blood cell was $0.548{\pm}0.071$ exposed seawater of pH 8.22 condition, on the other hand, DNA tail moment $1.601{\pm}0.197$ exposed acidified seawater of pH 7.55 lowest condition. The approximate difference with level of DNA damage was 2.9 times between highest and lowest of pH. DNA damage with decreasing pH was significantly increased with DNA tail moment on blood cell of marine fish (ANOVA, p < 0.001). Ocean acidification, especially inducing the leakage of sequestered $CO_2$ in geological structure is a consequence from the burning of fossil fuels, and long term effects on marine habitats and organisms are not fully investigated. The physiological effects on adult fish species are even less known. This result shown that the potential of dissolved $CO_2$ in seawater was revealed to induce the toxic effect on genotoxicity such as DNA breakage.

• 한국수산과학회지
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• 제51권4호
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• pp.450-455
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• 2018

We examined correlations of the density of fish farms with the distributions of indicator bacteria (Escherichia coli, fecal streptococci) and a bacterial fish pathogen (Streptococcus parauberis) off the coastline of Jeju Island. Seawater samples were collected at four coastal sites on the Island [Aewol (control), Gujwa, Pyoseon and Daejeong] in June, August and October 2016. The indicator bacteria were generally more frequently isolated from samples taken in August when water temperatures and human activities on nearby beaches were highest. Although fish farms were least common at Daejeong, the numbers of isolated fecal indicator bacteria were highest in the seawater and effluent water collected from this site. Hence, fish farms were not likely major contributors of indicator bacteria at Daejeong. We found discrepancies between the isolated bacterial counts and the predicted bacterial copy numbers deduced from our qPCR results, indicating that this pathogen may exist in a viable but non-culturable (VBNC) state in seawater. Thus, livestock wastewater and chemical fertilizer loading off Jeju Island may negatively impact seawater quality more than the effluent released from fish farms does.