• The Journal of Fisheries Business Administration
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• v.45 no.2
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• pp.85-95
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• 2014

Fish stocking is important element of land-based aquaculture management. To maintain constant stocking rate considering biological and economic condition is a convenient strategy in intensive aquaculture. This study is aimed to analyze the effect of over-stocking(more than aquaculture capacity) for certain periods of time. This study make the mathematical decision making model that finds the value of decision variable to minimize cost that sums up the water pool usage cost and sorting cost under critical standing corp constraint. The proposed mathematical decision making model was applied to 12 sample combination of sorting cost and the number of fish on the Oliver flounder culture farms. If a immature fish can be sold for high price than farming cost, restricted over-stocking resulted in a improvement of economic performance. When extensive comparable biological and market data become available, analysis model can be widely applied to yield more accurate results.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.5
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• pp.480-485
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• 2012

The hemocytes of the tunicate Halocynthia roretzi are classified into six types based on their size, cellular form, and fine structure of the cytoplasmic granules: hyalinocytes, granulocytes, phagocytes, nephrocytes, morula cells, and multi-vacuole cells. Based on cell size, they are ordered multi-vacuole cells ($7.5{\mu}m$)>nephrocytes ($7.1{\mu}m$)>phagocytes ($6.8{\mu}m$)>granulocytes ($6.1{\mu}m$)>morula cells ($5.7{\mu}m$)>hyalinocytes ($5.4{\mu}m$). The proportion of hemocytes is ranked in the order multi-vacuole cells (54.8%)>nephrocytes (16.9%)>granulocytes (9.9%)>morula cells (8.8%)>phagocytes (6.1%)>hyalinocytes (3.5%).

• The Journal of Fisheries Business Administration
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• v.36 no.1 s.67
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• pp.139-153
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• 2005

Marine fish aquaculture has been introduced on the East sea since 1964. The production volume of the marine aquaculture has been increasing drastically since 1990 with the technological improvements and the introduction of new species. However, the increasing costs of feed, seedlings and medical supplies and the decreasing prices due to the increase in the imports and domestic production have decreased the profits in the aquaculture business. Futhermore, the damage from the natural disasters such as red tides and typhoons has accelerated the exit from the business. Even though managing abilities to overcome the business crisis caused by the above factors are required, business managers based on the small scale family businesses do not have enough managing abilities to deal with the difficulties in the business. On the other hand, advanced countries in the marine aquaculture such as Norway have reached the stage where the managing abilities of marine aquaculture are similar to those in the manufacturing industry. And the number of large scale aquaculture farms with developed technologies and advanced marketing strategies in those countries is increasing. Considering that the marine aquaculture in Japan under the similar fishery systems of Korea has developed the state-of-the-art management skills or lead to large scale management, it is difficult to expect the decrease in the production costs under the small scale family business in Korea and this will lead to the decreasing competitive advantage over the imported seafood. Therefore marine aquaculture in Korea needs to increase the economy of scale to acquire the competitive advantage. This study addresses the possibility of introducing the large scale aquaculture system in Korea by analysing the factors and process of leading to large scale businesses in the aquaculture in Japan.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.170-178
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• 2024

This study aimed to quantitatively analyze the risk using data from 329 safety accidents that occurred in aquaculture fisheries management vessels over the recent five years (2018-2022). For quantitative risk analysis, the Bayesian network proposed by the International Maritime Organization (IMO) was used to analyze the risk level according to the fishing process and cause of safety accidents. Among the work processes, the fishing process was analyzed to have the highest risk, being 12.5 times that of the navigation, 2.7 times that of the maintenance, and 8.8 times that of the loading and unloading. Among the causes of accidents, the hull and working environment showed the highest risk, being 1.7 times that of fishing gear and equipment, 4.7 times that of machinery and equipment, and 9.4 times that of external environment. By quantitatively analyzing the safety accident risks for 64 combinations of these four work processes and four accident causes, this study provided fundamental data to reduce safety accidents occurring in aquaculture fisheries management vessels.

• Development and Reproduction
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• v.20 no.3
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• pp.207-217
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• 2016

In this study, we investigated the characteristics of CCK-producing cells and mucus-secreting goblet cells with respect to stomach fish and stomachless fish of the Gobiidae in order to provide a basis for understanding the digestive physiology. Hairychin goby (Sagamia geneionema), which is stomachless fish, the numbers of mucus-secreting goblet cells is highest in the posterior intestine portion (P<0.05), while CCK-producing cells are scattered throughout the intestine. Gluttonous goby (Chasmichthys gulosus), which is stomach fish, mucus-secreting goblet cells are most abundant in the mid intestine portion (P<0.05), whereas CCK-producing cells are observed only in the anterior and mid intestine portion. Trident goby (Tridentiger obscurus) which is stomach fish, mucus-secreting goblet cells were most abundant in the mid intestine portion (P<0.05). CCK-producing cells are found in the anterior and mid intestine portion. Giurine goby, Rhinogobius giurinus which is also stomach fish, the largest number of mucus-secreting goblet cells showed in anterior intestine portion except for esophagus (P<0.05). CCK-producing cells are present only in the anterior and mid intestine portion. In S. geneionema, digestive action occurs in the posterior intestine portion to protect and functions to activate digestion. In contrast, in C. gulosus, T. obscurus and R. giurinus, their digestive action occurs in the anterior and mid intestine portion to protect and functions to activate digestion. Further studies of the modes of food ingestion by these fish, the contents of their digestive tracts, and the staining characteristics of the goblet cells need to be carried out.

• The Journal of Fisheries Business Administration
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• v.41 no.1
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• pp.53-72
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• 2010

The objects of this study are to consider the current features and the development process of the utilizing system of aquaculture farms in Japan, and to suggest the theoretical basis for improvement of aquaculture system of Korea in the future through the analysis of background of the liberalization theory proposed recently. The aquaculture-fishery system of Japan was begun from the Meiji Era Fishery Act and New Fishery Act of the World war II. A small sum of fishery fee is paid to the fishery cooperative having fishing rights for securing fishing area newly, because the aquaculture of Japan belong to fishery cooperative not individual ownership of union membr of cooperative society, the other words, cultivation fisheries household. In case of Korea, there are several differences with Japan as follows; almost cultivation fisheries household has a individual license, the lisence of fishing rights are recognized as an article, the license of fishing lights are able to do sale. Therefore, it is needed to paid a lots of money for securing fishing area newly. On the other hand, advanced countries in the marine aquaculture such as Norway have reached the stage where the managing abilities of marine aquaculture are similar to those in the manufacturing industry. And the number of large scale aquaculture farms with developed technologies and advanced marketing strategies in those countries is increasing. Considering that the marine aquaculture in Japan under the similar fishery systems of Korea has developed the state-of-the-art management skills or lead to large scale management, it is difficult to expect the decrease in the production costs under the small scale family business in Korea and this will lead to the decreasing competitive advantage over the imported seafood. Therefore marine aquaculture in Korea needs to increase the economy of scale to acquire the competitive advantage.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.159-170
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• 2014

The effect of substances discharged from copper alloy mesh on the survival rate, growth, and health status of Sebastes schlegeli was investigated. Survival rate of experimental group was 10% higher than control group. There was no significant difference in weight gain and SGR between control group and experiment group (P<0.05). Glucose concentration was lower in the experimental group than that in the control group. GOT and GPT contents did not show significant difference during experiment except for the early three months of experiment (P<0.05). Ammonia concentration had not significantly changed in the experimental group, but it had increased until four months of experiment and then decreased afterwards in the control group. TCHO had decreased in the experiment group compared with that of control group. Copper and zinc contents had increased as compared with those in the initial stage of experiment with no significant difference between experiment group and control group (P<0.05). Histological analysis for the liver revealed that liver tissues were not particularly different from those in control group. There were no significant differences in survival rate, growth, and hematological characteristic between control group and experiment group (P<0.05). Though copper and zinc were accumulated as compared with those during the initial stage of experiment, the levels were lower than permissible levels for copper and zinc. As a result, copper alloy mesh would not adversely affect on the survival rate, growth, and health status of fishes.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.204-212
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• 2013

This study analyzed the occurrence of tunic softness, survival rate, metabolic rate and histopathologic changes arising from the effect of hypoxic environment in order to find the causes of occurrences of tunic softness, which manifests as the key phenomenon of mass mortality of Halocynthia roretzi. Regarding the survival of H. roretzi with reduction in dissolved oxygen, all the entities died on the 4th day of exposure to the dissolved oxygen concentration of $2mg\;L^{-1}$ while 50% mortality was observed on the 5th day of exposure to the dissolved oxygen concentration of $3mg\;L^{-1}$. Therefore the 5 days-$LC_{50}$ was found to be $3.55mg\;L^{-1}$ (1.86~$4.96mg\;L^{-1}$). However, occurrence of tunic softness was not observed during the period of exposure to low oxygen concentration. The oxygen consumption rate significantly decreases at the dissolved oxygen concentration of less than $5mg\;L^{-1}$ in comparison to the control group. Therefore, it is presumed that H. roretzi controls the respiration rate for prescribed period of time when exposed to hypoxic environment. Regarding the histopathologic changes in the gill, digestive gland and cyst of H. roretzi due to hypoxic environment, necrosis of epithelial layer, in filtration of blood cells, and condensation of nucleus that compose each of the organs were observed. Regarding morphological changes, the decrease in volume with shrinking of the tunic, discoloration of the internal organs and necrosis of gill and hepatopancreas were observed.

• The Journal of Fisheries Business Administration
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• v.46 no.3
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• pp.129-141
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• 2015

Because land based aquaculture is restricted by high investment per rearing volume and control cost, good management planning is important in Land-based aquaculture system case. In this paper master production planning was made to decide the number of rearing, production schedule and efficient allocation of water resources considering biological and economic condition. The purpose of this article is to build the mathematical decision making model that finds the value of decision variable to maximize profit under the constraints. Stocking and harvesting decisions that are made by master production planning are affected by the price system, feed cost, labour cost, power cost and investment cost. To solve the proposed mathematical model, heuristic search algorithm is proposed. The model Input variables are (1) the fish price (2) the fish growth rate (3) critical standing corp (4) labour cost (5) power cost (6) feed coefficient (7) fixed cost. The model outputs are (1) number of rearing fish (2) sales price (3) efficient allocation of water pool.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.223-224
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• 2003

Information on the fate of the added nutrients is essential for the assessment of the food utilization, pond fertility, water quality and processes in the sediment (Boyd, 1985). Also, they are useful for qualifying environmental impacts of aquaculture and for environmental management. The purpose of this experiment was to assess the fate of nitrogen and organic matter entering aquaculture ponds and the relative importance of the different resources. (omitted)