• The Journal of Fisheries Business Administration
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• v.52 no.3
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• pp.27-38
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• 2021

This study is aimed to figure out the productivity and variability of cage-aquaculture changes. According to the analysis, the productivity of major fish species has been increasing, except mullet. Although the regional productivity has decreased in the last two years, it has been on the rise considering as a whole. Gyeongsangnam-do showed the highest level of productivity by region. Productivity by species was also higher than other regions in the cases of rock fish, mullet and sea bream followed by productivity of Chungcheongnam-do. The production of marine cage-culture in Jeollanam-do is the second largest in Korea in value/weight while its productivity is lower than that of Chungcheongnam-do. When it comes to comparison by region, Gyeongsangnam-do shows the lowest productivity variation. And Jeollanam-do shows the second-lowest variation in productivity that is only about half of that of Chungcheongnam-do province. Thus, it is found that Jeollanam-do region has an advantage in management stability while its productivity is low. On the other hand, productivity by species was also analyzed. Gyeongsangnam-do has the highest productivity by species for rock fish, mullet and sea bream whereas rock bream productivity is the highest in Jeollanam-do. Therefore, it probably needs to reflect these results when choosing regional-focused incubation fish species.

• The Journal of Fisheries Business Administration
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• v.25 no.2
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• pp.115-145
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• 1994

The objetives of this study are to find the economic feasibility of the polyculture and to give the economic information of the polyculture for aquaculture fishermen. The polyculture is defined as the rearing of several species together to make more efficient use of the growing space and the total ground environment. The economic feasibility analysis in the polyculture involves the profitability, the productivity, and the risk reduction effect. The results of the economic feasibility analysis in the polyculture are as follows; First, in the profitability analysis, the solid utilization of ground in the polyculture is more profitable than the monoculture. The profitability owing to the plane utilization of the ground in the polyculture is positioned between those of the monoculture of each speices. Second, in the productivity analysis, oyster and sea squirt are diminishing returns to scale. Third, the variation on the average rate of return in the polyculture products is smaller than that of the monoculture. Finally, the result of comparison between the polyculture and the monoculture shows that the polyculture in coastal area is more profitable and more efficient than the monoculture. Most of cultivating species are selective in their diet Thus, stocking different kinds of cultivating species will efficiently utilize space and food It seems that polyculture is more appropriate for those species that live in different ecological niches. We think that the production per unit of ground can be increased, and the fixed cost per unit of output be reduced, so the polyculture is more profitable than the monoculture. Based on the above results, we concludes that the polyculture is economically feasible when profitability and productivity are increased and simultaneously the variation of average rate of return in the polyculture is smaller than that of the monoculture.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.570-581
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• 2013

To improve productivity of aquaculture animals with management of culturing grounds, survey of mariculture management area in Ongjin-gun about water quality and sedimentary environment had been conducted on June, August and November in 2011. Water temperature in surface and bottom waters ranged from 9.49 to $24.14^{\circ}C$. Salinity and dissolved oxygen concentrations were in the range of 23.19~31.49 and 5.48~9.36 mg/L, respectively, depending on the variation of water temperature. The average concentration of COD was 1.57 mg/L and the concentrations of DIN and DIP showed entirely low level. As the result of grain size analysis, sand(56.66 %) and silt(34.60 %) were predominated. The Mz of sediment showed a variation of 2.59 to $6.62{\O}$ and sorting appeared to be poorly sorted. The concentrations of COD and IL in surface sediment ranged from 1.00 to $11.03mg/g{\cdot}dry$ and 0.72 to 5.29 %, respectively, which showed relatively good positive correlations. On the environmental assessment of trace metals in surface sediment, geoaccumulation index ($I_{geo}$) class indicated that sediments were not contaminated by most of metallic elements except Cr and As. Our result implies that this study area showed good water quality and sediments were not polluted by organic matters and metallic elements.