• Journal of fish pathology
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• v.18 no.2
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• pp.187-195
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• 2005

Effluent of aquaculture industry has caused a growing concern regarding its environmental impact. We assessed the use of flounder farming sewage as supplement of diet, to minimize the impact of aquaculture on the environment or also establish the technique for the recycling of effluent sediment derived from land-based seawater fish farm. In order to investigate the effects of a fermented aquaculture waste on biochemical responses of olive flounder (Paralichthys olivaceus), fermented products of aquaculture wastes were used as test compounds that cause hepatic and renal stress through the induction of oxidative stress in liver and kidney. Hepatosomatic index (HSI), glutathione content and glutathione dependent enzyme were not significantly different and no correlation was found within the different types of fermentation condition or supplement concentration, except for significant increases in 50% fermentation group and 50% concentration group in case of glutathione peroxidase activity and HSI value, respectively. These results showed addition of fermented aquaculture sewage may be an economic artificial sources of diet for fish aquaculture practices without affecting the function and safety in view of biochemical examination.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.203-213
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• 2011

Agriculture modern environments can vary due to factors such as land consolidation and ditch enhancement projects. But, these improvements projects can include cover-ing-up of irrigation ditches with concrete, increasing the drop between paddy field and drainage ditches, which might decrease the abundance and diversity of fish fauna around paddy fields. In this study, for the management of agrobiodiversity on fish in paddy fields, we installed a small-scale fishways between paddy fields and drainage ditches, and evaluated the effects on the eco-connection of the paddy fields, ditches and stream. Five fish species were recovered at the drainage ditches. The species exhibited characteristics spawning and growth based on the paddy field. The results indicate that the five fish species could ascend the paddy fields through the small-scale fishways. There are no difference of species numbers at ditches of environment-friendly agriculture paddy fields (A) and good agricultural practices (B) region, but individual numbers were higher at the B region. This result could be interpreted as indicating that ditch diversity was affected by positional properties rather than farming practices because the water flow and connection to adjacent stream of B region were better than A region. After ascertaining the fish species capable of ascending in a pre-survey of the drainage ditches, we set up small-scale fishways at the drop between paddy fields and drainage ditches. Three species of fish (Aphyocypris chinensis, Misgurnus anguillicaudatus, M. mizolepis) arrived at the paddy fields via small-scale fishways. The main movement time was from 18:00~24:00 and 00:00~06:00, indicating a preference for the night time period rather than the day period for migration. Concentrating the operation time from night to dawn seems prudent for effective management of small-scale fishways.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.1
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• pp.45-54
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• 2020

In this study, an automatic system for improving the working environment and increasing production efficiency of a laver aquaculture industry in Korea was developed by combining a hydraulic control system and a load cell in a current landing work of the laver. The improved gathering laver system allowed the automatic gathering process of the laver in the sea with the hydraulic control system connected to a cutting machine of the laver on the operating ship, which has been used for gathering the laver semi-automatically in a form of the traditional farming method. The transporting process of the laver from an operating ship to the land was improved as follows. A frame installed on the operating ship and the bag nets were designed and made to hold about 1,000 kg of the laver inside. The bag nets contain the laver on the improved operating ship were tied in knots and hooked on a crane using a load cell. The weight is measured immediately by lifting the bag nets through the load cell system. Weight information is communicated to the fishermen and successful bidders through the application. The advantages of the improved system can help fishermen to fish by improving their working environment and increasing production efficiency. The field survey to improve the landing operation of the laver aquaculture was conducted in Gangjin, Goheung, Shinan, Wando, Jindo, and Haenam in South Jeonnam Province. A total of 10 sites including Gunsan in Jeonbuk Province, Daebu Island in Ansan City, Jebu Island in Hwaseong City in Gyeonggi Province, and Seocheon in Chungnam Province were searched to collect data. Prototypes of the system were tested at the auction house of laver located in Goheung, where laver collection using hydraulic control and landing using road cell could be improved.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.2
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• pp.130-139
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• 2015

To assess the noise stress of shrimp farms reasonably, we need a noise observation data underneath the waters first. But, it did not collect yet and airborne noise transfers to water noise wave using transition calculation. In case of construction of solar energy without noise stress protection wall, the threshold values (140 dB) from circumstance of underwater noise exceed within 17m at $S_2$ (15m away from source) and $S_3$ (15m away from source). Considering additional way to decrease the construction noise, all cases including minimum mode(Case A), general mode(Case B), and maximum mode(Case C) meet the guideline of underwater noise for fish farms. In case of the underwater noise could affect the fish farm, it is necessary to understand about farming species such as shrimp, monitoring of present states, and protection way under the construction.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.287-304
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• 2007

This study was carried out to investigate spatio-temporal variations of benthic environment and macrobenthic polychaete communities in Gamak Bay where excessive organic matters from untreated sewage effluents and fish and shellfish farming activities have been accumulated in certain regions. Such environmental variables as sediment composition, organic content, acid volatile sulfide and dissolved oxygen content etc. were measured and polychaete specimens were taken in September 1999 and February 2000. In September 1999, organic contents were up to three times higher in the northwestern part of the bay and the area closed to Gukdong harbor than in the rest of the bay. In particular, benthic environment of the northwestern part of the bay was extremely deteriorated by the occurrence of hypoxia and highly concentrated sulfide. Of 28 stations investigated in summer, 5 stations located in the northwestern part were azoic. In the rest of the stations, a total of 119 polychaete species were sampled with a mean density of 900 $ind./m^2$. While species richness was higher in the entrance and central part of the bay where water exchanges with open sea were relatively active, density was higher in the moderately enriched stations neighbouring Gukdong harbor and fish farms where such potential indicators of organic pollution as Aphelochaeta monilaris, Lumbrineris longifolia were largely dominant. In February 2000, a total of 81 polychaete species appeared with a mean density of 2,802 $ind./m^2$ from 12 stations sampled in winter. Azoic areas were recolonized by Capitella capitata, Pseudopolydora paucibranchiata and Dipolydora socialis which showed maximum density in the innermost station. On the other hand, the rest of the stations were dominated by Euchone alicaudata and Praxillella affinis. The configuration of the stations sampled in summer and winter on the multidimensional scaling plots reflected the position of each stations within the bay in which there were great differences in organic content, sulfide concentration and oxygen content rather than in sediment composition. Therefore, heterogeneities in polychaete community structure in Gamak Bay were primarily influenced by the degree of the disturbance depending on the position within the bay.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.508-515
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• 2006

This study was conducted from July to December 2004, in order to find measures to improve the water quality and the function of pond ecosystems which are often negatively affected by phytoplankton and suspended particle matters. Most of the time, the management of ponds in Korea does not consider the ecological concepts such as self-purification and nutrient recycling. Instead, conventional methods depend on other factors such as fish farming and the function of fountains and waterfalls. Sustainability of pond ecosystems must be studied with the highest emphasis given to water quality. Water discharges of inflow and outflow as well as balance adjustment for different factors must be thoroughly studied. There is a great need for studies on sustainability because it can be realized through the horizontal or vertical balances of an ecosystem. Our current research offers useful information to the academia and public on maintaining sustainability in terms of structure and function of the pond.

• Journal of Life Science
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• v.26 no.3
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• pp.309-317
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• 2016

Industrial advancements have resulted in food culture development, followed by increased seafood consumption and large-scale seafood farming, which has been accompanied by an increased prevalence of fish disease. The antibiotic oxytetracycline (OTC) is commonly used to prevent and treat bacterial diseases in fish. However, overuse of OTC had led to negative aspects. In view of this, we conducted a research with regard to aspects of remnants on olive flounder skin, liver, and muscle through dipping treatment and oral feeding of OTC and analyzed the results with bioassay and HPLC quantitative analyses. The dipping treatment was carried out once with 25 g/ton/hr of OTC, and the oral treatment with 62.5 mg/kg body weight/7 days. The results underwent a bioassay analysis. The dipping group reacted only on the skin right after dipping, while the oral feeding group responded on the skin for 77 days after feeding and on the muscle for 14 days. In the dipping group, the HPLC quantitative analysis revealed remnants in the skin on the 37th day and on the 13th day in the liver group. No remnants were found in the muscle, even immediately after dipping. In the oral feeding group, there was a high concentration (1.07 mg/kg) of remnant in the skin, even on the 77th day. 0.56 mg/kg in the liver, even a small amount, and no remnant in the muscle on the 42nd day. To sum up, the results suggest that it will not be harmful to our body to observe the OTC withdrawal period of 40 days with the muscle because OTC will hardly remain on it. When using olive flounder for sashimi, the skin and liver should not be used for broth, as the quantity of OTC residue is several times higher than that found in muscle. As previous studies reported that the concentration of remnants gradually decreased with heating, so it was likely to lessen, depending on the cooking temperature.

• The Journal of Fisheries Business Administration
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• v.15 no.1
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• pp.1-57
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• 1984

The fisherman has been playing the roles of forming the fisheries village and surviving the fisheries production. Therefore, we should understand the nature of the fisherman's successor-cultivation which has been performed in order to maintain equlibrium between the fisheries economy and the national economy. Thesedays, fisherman's successor-cultivation mainly has been undertaken by the government in order to facilitate forming the economic foundation of fisherman's successor who has intended to choose "fisheries" as his own occupation in the future. From the above-mentioned, we find the meaning of the undertaking as both securing the foundation of living permanently and having the worth-while life of a professional fisherman by the survival and growth of his own business. And then, choosing the "fisheries" as an occupation, the successor should be satisfied with the requisites of occupation: 1) maintaining one's living, 2) working out one's individuality, 3) fulfilling one's social role-through engaging in the fisheries. Therefore, in order to have these requisites satisfied, I intend to suggest the followings : Firstly to maintain one's living, the environment of fisheies village should be kept in good condition to facilitate the successor's economic performance. Secondly to work out one's individuality, the fisheries' educational system should be adjusted to improve fisherman's ability. 1 hope to institute "the course of regional fisheries management" in fisheries high school and junior vocational collage, and "the school of fisheries management" for the learning of advanced fisheries knowledge. Thirdly to fulfill one's role, the opportunity actively participating in decision-making of the village's affair should be prepared more sufficiently, and the present fishing-centered fisheries system should be reformed into the fish-farming-centered fisheries system. To do this, the long-perspective vision is necessary. These three suggestions are come out from the macro-view point. Meanwhile the fisherman as an individual to improve his business is from the micro-view point. That is, the public aid, financial and legal, should be prepared. The above-mentioned suggestions are necessary to equalize fisherman's social status with other professional's especially from the result of improving the successor's economic force. Therefore, the principle of cultivating the fisherman's successor should be the principle of social equilibrium. be the principle of social equilibrium.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.1
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• pp.41-48
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• 2012

Red tide is a natural phenomenon temporary blooming harmful algal with changing sea color from normal to red, which fish and shellfish die en masse. It also give a bad influence to coastal environment and sea ecosystem. The damage of sea farming by a red tide has been occurred each year which it cost much to prevent disasters of red tide blooms. Red tide damage and prevention cost of red tide disasters can be minimized by means of prediction of red tide blooms. In this paper, we proposed the red tide blooms prediction method using ensemble train. The proposed method use the bagging and boosting ensemble train methods for enhancing red tide prediction and forecast. The experimental results demonstrate that the proposed method achieves a better red tide prediction performance than other single classifiers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.2
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• pp.67-83
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• 2012

In order to evaluate die geochemical characteristics of sediment in a semi-enclosed bay used as shellfish and fish farming area, the concentrations of metallic(V, Cr, Mn, Fe, Co. Ni, Cu, Zn, Ag, Cd, Hg, Ph, As) and non-metallic(P, Se) elements and uranium were measured in the surface sediment samples collected from 19 stations of Gamak Bay in April 2010. Metal contamination status in the sediments were also evaluated using the sediment quality guidelines(SQGs) proposed by the National Oceanic and Atmospheric Administration(NOAA) and the enrichment factor(EF). The concentrations of elements in sediment were mainly controlled by quartz-dilution effect(V, Cr, Fe, Co and Ni), the dilution effect of organic matter(Cd and U), and metal redistribution by the decomposition of organic matter(Mn, Ag, As, and Se). The concentrations of metals, except As and Ni, in sediments from all sampling stations were lower than ERL values of NOAA. Conclusively, the surface sediment of Gamak Bay was slightly polluted with Ni, Ag, Cd, and Cd but was not polluted with other elements on the basis of EF results. Our results suggest that the surface sediment in Gamak Bay is not polluted by metallic elements.