• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.520-529
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• 2014

Experiment was set up to analyze bycatch and discards situation including snow crap Chionoecetes opilio of whelk trap. Four types of trap were used: drum type trap with PE net; drum type trap with PBS net; cylinder type trap with PE net; and cylinder type net with PBS net. Three funnels were attached in drum type trap and two funnels were used in cylinder type trap. A fleet of traps was consisted with one hundred traps. 25 traps of each type were set on a line in repeated sequence. Field experiments were conducted with 6 fishing operations in the Uljin waters, East Sea in July 2014. Catch of target whelks were 173,261 g and catch rate was 48.7% of total catch, while bycatch were 182,571 g, 51.3% of tatal catch. The catch rate of bycatch was 2.6% higher than that of target catch. Bycatch weight of snow crap was the highest as 142,987 g and formed about 40.2% of total catch, followed giant octopus, Enteroctopus dofleini, 31,762 g (8.9%). Bycatch rate of cylinder type trap was 2.3 times higher than that of drum type trap. Discard rate (discard/(discard+landing)) was 43.6%. Discard rate was the highest at cylinder type trap with PBS net as 63.1%, followed cylinder type trap with PE net as 47.9%, drum type trap with PE net as 33.4%, the lowest at drum type trap with PBS net as 22.1%.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.105-111
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• 2006

This paper describes Fishery Safety and Security System which is to secure an aquaculture area. The system composed with various functional modules to implement selectively available system providing low cost to high cost and simple function to high function according to user's requirement in a practical fishing fields. Sea trial tests are carried out at Abalone farm, located in Jin island, Jeonranam province and it is found that the system can guard the wide area of cultivating farm field.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.320-323
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• 2008

This study attempts to establish a system extracting and monitoring cultural grounds of seaweeds (lavers, brown seaweeds and seaweed fulvescens) and abalone on the basis of both KOMPSAT-2 and Terrasar-X data. The study areas are located in the northwest and southwest coast of South Korea, famous for coastal cultural grounds. The northwest site is in a high tidal range area (on the average, 6.1 min Asan Bay) and has laver cultural grounds for the most. An semi-automatic detection system of laver facilities is described and assessed for spacebome optic images. On the other hand, the southwest cost is most famous for seaweeds. Aquaculture facilities, which cover extensive portions of this area, can be subdivided into three major groups: brown seaweeds, capsosiphon fulvescens and abalone farms. The study is based on interpretation of optic and SAR satellite data and a detailed image analysis procedure is described here. On May 25 and June 2, 2008 the TerraSAR-X radar satellite took some images of the area. SAR data are unique for mapping those farms. In case of abalone farms, the backscatters from surrounding dykes allows for recognition and separation of abalone ponds from all other water-covered surfaces. But identification of seaweeds such as laver, brown seaweeds and seaweed fulvescens depends on the dampening effect due to the presence of the facilities and is a complex task because objects that resemble seaweeds frequently occur, particularly in low wind or tidal conditions. Lastly, fusion of SAR and optic spatial images is tested to enhance the detection of aquaculture facilities by using the panchromatic image with spatial resolution 1 meter and the corresponding multi-spectral, with spatial resolution 4 meters and 4 spectrum bands, from KOMPSAT-2. The mapping accuracy achieved for farms will be estimated and discussed after field verification of preliminary results.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.61-73
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• 2022

Stable isotope analysis (SIA) is being used in various research fields including environmental science, ecology, biogeochemistry, forensics, and archeology. In this paper, for the purpose of enhancing applications and utilizations stable isotope analysis techniques to aquaculture research, we would like to introduce the background knowledge necessary to utilize stable isotope analysis techniques. In particular, with a focus on the approach using natural abundance, the principle of fractionation (change in isotope ratio) that occurs in the process of the integration of elements into biological tissues and how stable isotope ratios are determined by fractionation. This paper is intended to suggest whether SIA is used as a valuable tool in the fields of ecology and environmental science. With the understanding of the field of stable isotopes through this paper, various applications of stable isotope ratios are expected in fisheries science and aquaculture research in the future.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.360-367
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• 2013

The mesh selectivity of the gillnet for Pacific herring (Clupea pallasii) was examined in field experiments with four different mesh sizes (63, 69, 75 and 81mm) from June to July, 2013 in the coastal areas of Imwon in Gangwon province. The fishing performance tests were conducted with a commercial Pacific herring gillnet and a biodegradable gillnet for Pacific herring together selectivity tests. The filed tests were carried out the total 11 times. The master curve of selectivity was estimated by the extended Kitahara's method. In the results, the catch number of Pacific herring was 9,409 (2,203kg) and occupied 84.2% in total catches weight. The optimal mesh size for 50% retention on first maturity size (female, 250mm) of Pacific herring was estimated as 64.5mm by master selectivity curves. The fishing performance of the biodegradable gillnet was showed to be equivalent with commercial gill for Pacific herring.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.131-139
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• 2012

Field experiment was performed from June 2010 to July 2011 to evaluate pollutants removal efficiency in the constructed wetland system for the treated wastewater and the river water. The wetland systems were constructed near Gyungan river. Two different systems with meandering shape were compared for seasonal base and operational period base. Several kinds of aquaculture are planted through the corridor of wetland system. Average removal rate of BOD, T-N and T-P for A system were 15.8%, 14.8% and 26.5%, respectively. Average removal rate of BOD, T-N and T-P for C system were 23.5%, 27.8% and 10.6%, respectively. The effluent from two wetland systems often exceeded effluent water quality standards for wastewater influent, however effluent water quality standards for river water. However, the wetland system can be useful to treat polluted river water and effluent from wastewater plant. Removal rate of pollutants in seasonal variation was the highest in summer for BOD and T-N, however the removal rates of T-P were higher in spring and autumn than in summer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.294-300
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• 1995

In aquaculture industrial field, an automatic management and control system is needed to cope with the difficulties such as expensive wage, ripe age of management worker and risk according to the unexpected change of environmental conditions in the aquarium. This paper introduces an automatic aquarium monitoring and control system. The system is developed using PC single board computer. A PC can be connected to multi-single hoard computers, and the communication between PC and single board computers is based on RS-422/485 interfacing method. The physical data of pH, DO, temperature and water level etc. are real-timely treated in the single board computer though individual transducers, transfered to the main monitoring PC through RS-422/485 communication, and those data are graphically shown on the PC monitor. Furthermore, the environmental circumstance can be monitored through the image processing system, and the emergency system can be operated under the condition of environmental incident such as electric power stoppage, DO deficiency, pump shut down and low level water etc.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.252-258
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• 2013

The quality and quantity of food organisms in fish seed production are important. The marine microalgae Nannochloropsis oculata are used as initial food organisms in the field. We investigated the effects of salinity (0, 10, 20, 30, 40 and 50 psu) on the lipid and fatty acid composition of N. oculata. Cultivation of N. oculata at varying salinities showed the highest growth rate at 20 psu. Total lipid content ranged from 17.26 to 18.63% at salinities from 0 to 50 psu). The nonpolar lipid content increased markedly at 30 psu and was highest at 15.55%. The polar lipid content was lowest at 30 psu, by 84.45%. It was also found that the omega-3 and EPA contents were inversely proportional to salt concentration. For the polar and nonpolar lipid compositions, there was no significant effect of salinity. Omega-3 polyunsaturated fatty acid content especially the content of EPA in the seawater larvae is the essential fatty acid in this food organism. It is thus advantageous to culture N. oculata at 20 psu.

• ALGAE
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• v.38 no.1
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• pp.71-80
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• 2023

The oomycete pathogens Pythium porphyrae, causing red rot disease, and Olpidiopsis spp. causing Olpidiopsis-blight, cause serious economic losses to Pyropia sea farms in Korea. During the washing step for Pyropia processing, these pathogens proliferate rapidly, significantly reducing the quality of the final product. To develop non-acidic treatments for these pathogens, various calcium salts were tested against the infectivity of P. porphyrae and Olpidiopsis pyropiae on Pyropia gametophytes, and calcium propionate was the most effective. When Pyropia blades were immersed in 10 mM calcium propionate for 1 h after inoculation with the oomycete pathogen, infection rate of both oomycete pathogens on day 2 was significantly lower (7.1%) than control (>95%). Brief incubation of Pyropia blades in calcium propionate also reduced the spread of infection. The infected area of Pyropia thallus was reduced to 14.3% of the control in 2 days after treatment with 100 mM calcium propionate for 30 s. In field experiments conducted in actual aquaculture farms, it has been shown that a brief 30 s wash every two weeks with 100 mM calcium propionate can effectively reduce the spread of oomycetes throughout the entire culture period. The above results suggest that calcium propionate can be a useful means for controlling the spread of oomycetes not only during laver processing but also during aquaculture.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.352-359
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• 2013

To estimate the mesh selectivity of gillnet for ocellate spot skate (Okamejei kenojei), the field tests were carried out 12 times with six different mesh sizes (121.2mm, 137.7mm, 151.5mm, 168.3mm, 178.2mm, 189.4mm) in the coastal waters of Taean, Chungcheongnamdo of Korea, 2010~2011. In the field tests, the total number of species was 31, and that of catch was 1,410 and the total weight was 618,006g. The number and weight of ocellate spot skate which is main target in this study were 1,004 and 434,592g, respectively. The catch in number of ocellate spot skate occupied about 71.2% in total catch. The others of catch species were marbled sole (8.4%), sea raven (4.4%), japanese swimming crab (4.2%) and flatfish (4.1%) and so on. The range of body disk width (DW) of ocellate spot skates which were caught in this study was 15.2~35cm and the mode was 27~29cm. The estimation equation of mesh selectivity using the extended Kitahara's method was expressed as s $(R)=s(DW/m)={\exp}\{(-0.56R^3-1.80R^2+12.96R-9.99)-4.26\}$. The optimum value of DW/m for 1.0 of retention probability in this estimation equation was estimated 1.899 and DW/m was estimated to be 1.194, 1.314, 1.395, 1.461 and 1.520 when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively. When applied to the retention probability of 0.5, the optimum mesh size was estimated to be 177.0mm on first maturity disk width 26.9cm of ocellate spot skate.