• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.3
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• pp.221-227
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• 2008

The black rockfish (Sebastes schlegeli) is an important commercial species in Korean fisheries. We used acoustic telemetry using coded ultrasonic transmitters to track the home ranges and homing routes of the black rockfish that inhabit in the Tongyeong marine ranching area. Twenty-four fish were released at five points. The distance from the capture point (C1) to the released point was 0 (R7), 0.2 (R1), 0.9 (R2), 1.3 (R3) and 1.9 (R4) km. Two of the three fish released at R1 (0.2 km) returned home in under 48hrs. Another was found 0.8km from C1. Two of the five fish released at R2 returned home, but it took over 250 days. None of the ten fish released at R3 and R4 returned home. Three of the ten fish moved 1.1-2.6 km from C1 and were found near a cage or a natural reef. Six fish were released at R7. The younger the fish, the wider was its movement range around the artificial reefs. Fish over 3 years old were likely to move less far.

• Ocean Science Journal
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• v.42 no.2
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• pp.117-127
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• 2007

The dynamics of phytoplankton abundance with seasonal variation in physicochemical conditions were investigated monthly at 10 stations around the Chagwi-do off the west coast of Jeju Island, Korea, including inshore, middle shore, and offshore in the marine ranching are a from September 2004 to November 2005. Water temperature varied from 12.1 to $28.9^{\circ}C$ (average $18.8^{\circ}C$), and salinity from 28.9 to 34.9 psu (average 33.7 psu). The chlorophyll a concentration was $0.02-2.05\;{\mu}g\;L^{-1}$ (average $0.70\;{\mu}g\;L^{-1}$), and the maximum concentration occurred in the bottom layer in April. A total of 294 phytoplankton species belonging to 10 families was identified: 182 Bacillariophyceae, 52 Dinophyceae, 9 Chlorophyceae, 12 Cryptophyceae, 6 Chrysophyceae, 4 Dictyophyceae, 13 Euglenophyceae, 6 Prymnesiophyceae, 5 Prasinophyceae, and 5 Raphidophyceae. The standing crop was $2.21-48.69\times10^4\;cells\;L^{-1}$ (average $9.23\times10^4\;cells\;L^{-1}$), and the maximum occurred in the bottom layer in April. Diatoms were most abundant throughout the year, followed by dinoflagellates and phytoflagellates. A phytoplankton bloom occurred twice: once in spring, peaking in April, and once in autumn, peaking in November. The spring bloom was represented by four Chaetoceros species and Skeletonema costatum; each contributed 10-20% of the total phytoplankton abundance. The autumn bloom comprised dinoflagellates, diatoms, and phytoflagellates, of which dinoflagellates were predominant. Gymnodinium conicum, Prorocentrum micans, and P. triestinum each contributed over 10% of the total phytoplankton abundance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.1
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• pp.32-49
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• 2010

Ecosystem-based fisheries management requires a holistic assessment of the status of fisheries by integrating fishery ecosystem indicators for management objectives. In this study four objectives were identified such as the maintenance of the sustainability, biodiversity and habitat quality and socio-economic benefits. The ecosystem-based fisheries assessment (EBFA) model to assess fisheries and their resources at the ecosystem level developed for Korean fisheries (Zhang et al., 2009) has a number of indicators for three management objectives. However, it was found that there were some overlapping components among indicators and that there were difficulties in assessing some indicators in the EBFA model. This study identified problems of the approach and suggested more pragmatic and simpler indicators. It also presented alternative reference points to assess indicators and discussed issues associated with the application of the EBFA model to a marine ranching ecosystem. In this study a total of 24 indicators were used for the assessment which included 4 socio-economic indicators. New indicators and reference points were demonstrated by applying it to the Uljin marine ranch.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.37-46
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• 2016

This study describes the spatio-temporal distributions in phytoplankton community such as species composition, standing crops and dominant species from April to November 2008 in the Uljin Marine Ranching Area (UMRA). A total of 123 species of phytoplankton belonging to 67 genera was identified. In particular, diatoms and dinoflagellates were occupied more than 60.5% and 34.6% of total species, respectively. The annual dominant species were Thalassiosira sp., Pseudo-nitzschia pungens in spring, Leptocylindrus danicus, Guinardia striata in early summer, Cheatoceros cirvisetus, Ch. decipiens in early autumn and Skeletonema costatum -ls (like species), Pn. pungens in autumn. Phytoplankton cell density fluctuated with an annual mean of $48cells{\cdot}mL^{-1}$ between the lowest value of $1.8cells{\cdot}mL^{-1}$ in early autumn and the highest value of $240cells{\cdot}mL^{-1}$ in spring. According to the cluster analysis, the phytoplankton community of the UMRA was characterized by the nutrient supply from land side and water movement as current.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2004.05a
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• pp.63-63
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• 2004

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2004.05a
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• pp.67-67
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• 2004

• The Journal of Fisheries Business Administration
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• v.29 no.2
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• pp.199-216
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• 1998

An economic appraisal of a proposed marine ranching project is analysed using capital budgeting model such as net present value(NPV) and internal rate of return( IRR) as well as sensitivity analysis and goal seeking model. Of the factors for economic appraisal, direct benefits are to be determined by estimated harvest, prices and costs incurred by catching fishes, and indirect benefits include the additional economic effect of recreational fishing. And judging the worth of these project options depends upon the choice of discount rate of which 8.5% is recommended here. On the basis of estimated production, prices and costs the project is expected to yield NPV=615 million won and IRR=8.8%, which is quite accepted for an economic feasibility, under the first scenario, and NPV= -127 million won and IRR=7.93%, which is rejected, under the second scenario. Sensitivity analysis has been performed by calculating the switching value and sensitivity indicator in respect of the main project parameters. The results suggest that the project NPV and IRR are especially sensitive to fishes(rock fish and other rock fish) prices and fixed costs. Finally goal seeking analysis is carried out in order to reach a desired level of performance like NPV=0 in respect of the amount of hatchery-reared juverniles, the prices and the discount rate.

• Journal of Ocean Engineering and Technology
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• v.30 no.3
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• pp.186-193
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• 2016

Recently in Korea, a marine ranching project has continued to grow with the increasing needs of sea development. Management techniques, including settlement reduction and scour protection, have been required for constructing and maintaining the artificial reefs of this marine ranching project. The generation of settlement and scour can be influenced by ground characteristics. In this study, various laboratory tests (penetration test, two-dimensional water tank test) were performed to determine the settlement and scour characteristics of artificial reefs under various ground conditions. Three kinds of ground reinforcement were prepared: unreinforced, geogrid, and hybrid bamboo mat. Penetration test results showed that the normalized settlement ratio of ground reinforced with a hybrid bamboo mat was smaller than those of unreinforced ground and geogrid-reinforced ground. Two-dimensional water tank test results showed that the scour characteristics of ground reinforced with a geogrid were more reduced and stable than unreinforced ground. The amount of scour and ground settlement also decreased with increasing reinforced area.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.2
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• pp.128-136
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• 2012

Hybrid surveys using hydroacoustic and fish sampling gears such as trammel net, trap were conducted to investigate total biomass, distribution and dominant fish species of the demersal fishes in the marine ranching area (MRA) of Jeju. Four surveys were carried out in June, August, October and November using 38kHz quantitative echo sounder. Catch data using trammel net and trap were used to calculate biomass and to examine dominant fish species. Fish schools were mainly detected in the waters of 20 meters below and around Chagwido waters. By the result of fishing experiments, fish species living in MRA of Jeju were about 40 species, dominant fish species of a detectable fish such as Family Sparidae and Family Monacanthidae etc. were identified 59.4~68.8% of total biomass. Based on the hydroacoustic data, fish length-weight function and target strength information, mean density of the demersal fish estimated were as follows; 0.88g/$m^2$ on June, 1.12g/$m^2$ on August, 1.35g/$m^2$ on October and 1.18g/$m^2$ on November. An estimated average biomass in MRA of Jeju was founded 20.5 tons in 2007, 20.6 tons in 2008, 23.0 tons in 2009, 25.9 tons in 2010. The results showed that biomass of MRA is getting increased slowly. Therefore the hybrid survey method using hydroacoustic and fish sampling gears is assured an effective biomass survey in the waters of mixed species.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.141-147
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• 2013

An artificila fish-reef is a artificail structure installed at marine ranching under the littoral sea. The artificial fish-reefs provide the function of fish spawning ground, habitation, nursery ground, and enhance the productivity of fising industry devastated by environmental pollution. After the installation of artificila fish-reef, continuous monitoring is demanded to check the validity of artificila fish-reef plan. However, the support of follow-up management is impossible because of the lack of a huge budget and professional manpower. Therefore, the artificial fish-reef combined with IT devices can be controled IT devices through the IT artificial fish-reef management system, and collect the marine environment information for the fair management. This paper shows the example of systematization for the management of artificial fish-reef based on the marine rancing management system.