• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.159-167
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• 2014

In this study, I examined the water quality and phytoplankton community in aquaculture laver farm in the southwest part of Aphae-do, South Korea, based on the young leaf stage, middle leaf stage, and adult leaf stage of laver thallus from October, 2013 to January, 2014. It was observed that the Aphae laver farm, as located in shallow waters, was found to have a serious resuspsension of the surface sediments due to physical disturbance caused by winds and tidal mixing. Such a resuspension of surface sediments coupled with nutrients supply obstructs light penetration into the sea for its huge amount of total suspended matters. As a result for this reason, it was viewed toimpedthe growth of phytoplankton was impeded as it also competes with laver to absorb the same kinds of nutrients as laver does during the laver growth period in winter. Such elements of the marine environment in Aphae laver farm are in contrast with the environment of Japan, where nutrients including dissolved inorganic nitrogen, in particular, are insufficient to cause the recent laver bad harvest, discoloration and quality degradation while large diatoms, with their higher nutrients absorption efficiency than laver, generate winter red tide. In other words, an important factor to maintain the high laver production in the southern parts of West Sea of Korea was found to be the marine environment of its laver farms where large diatoms are prevented from growing due to nutrients supply and dense seston weights from resuspended matters by physical disturbances.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.580-582
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• 2001

The Manila clam, Ruditapes philippinaMm (Pelecypoda: Veneridae) is present along the coasts of Korea, China and Japan. In particular, Recently, due to reclamation of tidal areas along the west coast, marine pollution, and reckless overharvesting of this clam, its standing stock has reduced for a decade. Therefore, it is necessary to manage the population of the clam with a proper fishing regime that will maintain an optimal population size in aqua farm. (omitted)

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1792-1800
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• 2016

This study is aimed to analyze the profitability of flatfish fry production farms in the Republic of Korea. The continuous and stable production of flatfish fries is one of important factors that increases the possibility of flatfish aquaculture's success. It is also the basis of aquaculture industry that estimates the quantity and quality of fishery products from aquaculture. Based on the surveyed data, production values and costs of flatfish fry production are estimated and compared to determine the profitability of flatfish fry production by farm. Results show that average return on sales of farms is 21.2%(12.4~26.3%), indicating that flatfish fry production would be profitable under the current production and market conditions. Sensitivity analyses of main variables (survival rate and selling price) indicate that the profitability of flatfish fry production farms can be significantly decreased when the survival rate and selling price would be slightly decreased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.511-518
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• 2019

Evaluating the habitat suitability of potential aquaculture sites for cultured species is critical to the sustainable use of tidal flats. This study evaluated the habitat suitability index (HSI) of 12 sites in a tidal flat aquaculture farm at Geunso Bay, Taean, in June 2016. The parameters used to model the suitability index were Growth (water temperature, chlorophyll ${\alpha}$, hydrodynamics), Survival (sediment-sand, mean size, air exposure), and Environment (DO, salinity). The HSI was calculated using weighted and No weighted geometric means. The results showed high habitat suitability at the bay's entrance (HIS; No weighted, 0.60-0.70; weighted, 0.60). Hydrodynamics, air exposure, sediment-sand and mean size are thought to have a significant impact on habitat selection by Manila clams Ruditapes philippinarum. This study explored the optimum habitat for Manila clams by calculating the HSI, providing basic data for tidal flat management.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.716-720
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• 2023

This study was designed to analyze the effects of reducing water turnover in olive flounder Paralichthys olivaceus farms, focusing on olive flounder growth, decreasing electricity costs, and developing measures to ensure business stability. Daily water turnover was set at 18 in the control group and six in the experimental group. Juvenile fish were reared for 12 months. No significant differences in mean weight were observed between groups until five months. After five months, the mean weight of the control group grew significantly faster than that of the experimental group. Maintaining water turnovers leverl at six turnovers for the first five months after stocking juvenile fish and then increasing water turnover resulted in a 34.4% reduction in electricity costs compared to the control group. This approach presents a potential method to enhance the profitability of olive flounder farms and ensure stable productivity and profitability without sacrificing olive flounder growth.

• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1260-1269
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• 2024

The gastrointestinal (GI) tract of shrimp, which is comprised of the stomach, hepatopancreas, and intestine, houses microbial communities that play crucial roles in immune defense, nutrient absorption, and overall health. While the intestine's microbiome has been well-studied, there has been limited research investigating the stomach and hepatopancreas. The present study addresses this gap by profiling the bacterial community in these interconnected GI segments of Pacific whiteleg shrimp. To this end, shrimp samples were collected from a local aquaculture farm in South Korea, and 16S rRNA gene amplicon sequencing was performed. The results revealed significant variations in bacterial diversity and composition among GI segments. The stomach and hepatopancreas exhibited higher Proteobacteria abundance, while the intestine showed a more diverse microbiome, including Cyanobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Chloroflexi, and Verrucomicrobia. Genera such as Oceaniovalibus, Streptococcus, Actibacter, Ilumatobacter, and Litorilinea dominated the intestine, while Salinarimonas, Sphingomonas, and Oceaniovalibus prevailed in the stomach and hepatopancreas. It is particularly notable that Salinarimonas, which is associated with nitrate reduction and pollutant degradation, was prominent in the hepatopancreas. Overall, this study provides insights into the microbial ecology of the Pacific whiteleg shrimp's GI tract, thus enhancing our understanding of shrimp health with the aim of supporting sustainable aquaculture practices.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.3
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• pp.116-121
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• 2004

Treatability tests were conducted to study the feasibility of EMMC process as a recycling-water treatment system in high density seawater aquaculture farm. To study the effect of organic and ammonia nitrogen loading rate on system performance, hydraulic retention time was reduced gradually from 12hr to 10min. The conclusions are can be summarized as follows. When the system HRT was reduced from 12hr to 2hr gradually, there was little noticeable change(reduction) in ammonia nitrogen removal efficiencies. However, removal efficiencies were decreased dramatically when the system was operated under the HRT of less than 2hr. In case of organics(COD), there was no dramatic change in removal efficiencies depending on HRT reduction. COD removal efficiencies were maintained successfully higher than 9％ when the system was operated at tile HRT of 10 min. System performances depending on media packing ratio in the reactors were also evaluated. There were little differences in each reactor performances depending on media packing ratio in reactor when the reactors were operated under the HRT of longer than 1hr. However, differences in reactor performances were considerably evident when the reactors were operated under the HRT of shorter than 1hr. When comparing reactor performance among 25％, 50％,7 5％ packed reactor, it can be judged that media packing ratio more than 50％ plays no significant role in increasing reactor performance. For this reason, packing the media less than 50％ is more reasonable way in view of economic. Such a tendency shown in COD removal efficiencies well agreed with the variation of ammonia-nitrogen removal efficiencies according to the media packing ratio in reactors at each HRT. Difference in effluent ammonia-nitrogen concentration between 50％ media packing reactor and 75％ media packing reactor was negligible. When comparing with the results of 25％ packing reactor, difference was not so great.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.41-51
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• 2017

To understand the application in farm for the fish aquaculture, we investigated biological and pathological traits on red sea bream Pagrus major which were reared in each copper-alloy net cage and the synthetic fiber net cage for 9 months. Two groups of cage were made and set in Yokji-eup, Tongyoung, Gyeongsangnam-do in size of 25 m in diameter and 10 m of depth. Survival rate of the red sea bream in the rearing copper-alloy net cage and synthetic fiber cage showed 99.75% and 99.70% respectively, there was no significant difference. Daily weight growth rate in each net was shown to 2.13 g/day and 1.65 g/day. Health analysis by blood composition analysis showed a favorable result in the copper-alloy net cage rather than in the synthetic fiber net. Bioaccumulation of heavy metal such as Cu and Zn especially in gonad was higher than other organ. Bioaccumulation of Cu and Zn in the muscle was lower compared to the permitted standard for food safety. Pathogenic infection test discovered Microcotyle tai for parasite, V. alginolyticus and other five species for bacteria. But there was a little bit difference of bacteria infection in copper-alloy net cage and copper-alloy net cage is expected to be has antibacterial effect. Thus, copper-alloy net cage can be applied to farm considering its system stability, recycling, antibiosis and food safety.

• Journal of Aquaculture
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• v.8 no.2
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• pp.85-98
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• 1995

In Kunsan coastal areas, there are some plans to construct industrial zone and, it will affect physical and chemical parameters of marine environment of the area. As one of many environmental surveys on the aquacultural farm in Korean west coast, the survey on the bottom sediment characteristics of intertidal farm was conducted from May 1992 to April 1993. Dominant grain size was fine sand $(69-98\%)$ and the pH of sediment was ranged of $7.2\~9.1$. Especially the pH increased after embank was constructed. The water holding capacity was $11.1-28.1\%$ and showed high value in silt and clay area. The COD was 1.27 mg/g dry mud and increased after embank was constructed. The total organic matter content ranged of $0.84-8.11\%$ and the DO absorption was $0\~6.56 mg/g$ dry mud. The value of DO absorption showed low in winter and spring, but high in summer and fall. The total nitrogen and the sulfide were rang of $0\~402{\mu}g/g$ dry mud and $0\~122{\mu}g/g$ dry mud respectively. These values were high in summer and winter season, and higher in upper layer than that of lower layer in general.

• The Journal of the Korea Contents Association
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• v.21 no.1
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• pp.552-560
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• 2021

Currently, the domestic aquaculture industry is pursuing smartization, but it is still proceeding with human subjective judgment in many processes in the aquaculture stage. The prerequisite for the smart aquaculture industry is to effectively grasp the condition of fish in the farm. If real-time monitoring is possible by identifying the number of fish populations, size, pathways, and speed of movement, various forms of automation such as automatic feed supply and disease determination can be carried out. In this study, we proposed an algorithm to identify the state of fish in real time using underwater video data. The fish detection performance was compared and evaluated by applying the latest deep learning-based object detection models, and an algorithm was proposed to measure fish object identification, path tracking, and moving speed in continuous image frames in the video using the fish detection results. The proposed algorithm showed 92% object detection performance (based on F1-score), and it was confirmed that it effectively tracks a large number of fish objects in real time on the actual test video. It is expected that the algorithm proposed in this paper can be effectively used in various smart farming technologies such as automatic feed feeding and fish disease prediction in the future.