• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.387-401
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• 2006

This paper deals with the problem of a ratio-dependent prey- predator model with combined harvesting. The existence of steady states and their stability are studied using eigenvalue analysis. Boundedness of the exploited system is examined. We derive conditions for persistence and global stability of the system. The possibility of existence of bionomic equilibria has been considered. The problem of optimal harvest policy is then solved by using Pontryagin's maximal principle.

• The Journal of Fisheries Business Administration
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• v.33 no.1
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• pp.1-18
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• 2002

The observer program is being utilized In various fishing areas and fisheries internationally and nationally due to the its expected effectiveness in fisheries management and the collection of bioeconomic data necessary in fisheries management policy. The timely gathered data by observers play substantially a major role in decision-making fisheries policy such as the change in management measures, the application of season closure and area closure and etc. The expected effectiveness of the observer program In fisheries management, generally mentioned, is that it would lead to the increase in stock size from which the level of harvest would consequently increases. This study is aimed to analyze this tentatively expected effectiveness of the observer program in fisheries management. The changes in stock size and the level of harvest over time are analyzed under the observer program assuming the fishermen bear the cost of the observer program by investigating the change in fisherman's fishing activity under the observer program and by combining this changed activity with the biological model. The level of fishing efforts of fishermen was decreased from the results of the increase in fishing cost caused by the observer cost and the decrease in catchable stock size restricted by observers. This reduced level of fishing efforts enables stock size to increase over time and therefore, the expected level of harvest increases as time goes on. Another benefit under the observer program is to reduce management costs from the fact that fishermen are responsible for the cost of the observer program and the avoidance cost of fisherman responding to the fisheries regulation could be eliminated from the surveillance of observer. Therefore, it may possible to accomplish the cost-efficient fisheries management policy.

• Ocean and Polar Research
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• v.37 no.2
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• pp.161-177
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• 2015

This study analyzes the stock assessment of yellow croaker caught mainly by the Korean stow net and gill net fisheries focusing on single species and multiple fisheries. This study standardizes fishing efforts for the two fisheries using the general linear model and uses a surplus production model based on the exponential growth model. The Clarke Yoshimoto Pooley model estimates a maximum sustainable yield(MSY), an allowable biological catch(ABC), fishing efforts for MSY($E_{MSY}$) and for ABC($E_{ABC}$). The bio-economic model is used to estimate the maximum economic yield(MEY) and fishing efforts for MEY($E_{MSY}$). Also, the study employs an economic analysis to estimate the economic interaction between stow net and gill net fisheries. The economic analysis shows the profit accruing to the two fisheries from estimated ABC. Finally, the study compares TACs based on single species and single fishery to TAC based on single species and multiple fisheries. The study proposes that the TAC assessment is necessary for single species and multiple fisheries in order to preserve resources.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.4
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• pp.347-360
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• 2020

In this study, the Bayesian state-space model was used for the stock assessment of the Blackfin flounder. In addition, effective measures for the resource management were presentedwith the analysis on the effectiveness of fisheries management plans. According to the result of the analysis using the Bayesian state-space model, the main biometric value of Blackfin flounder was analyzed as 1,985 tons for maximum sustainable yield (MSY), 23,930 tons for carrying capacity (K), 0.000007765 for catchability coefficient (q) and 0.31 for intrinsic growth (r). Also the evaluation on the biological effect of TAC was done. The result showed that the Blackfin flounder biomass will be kept at 14,637 tons 20 years later given the present TAC volume of 1,761 tons. If the Blackfin flounder TAC volume is set to 1,600 tons, the amount of biomass will increase to 16,252 tons in the future. Lastly, the biological effectiveness of the policy to reduce fishing effort was assessed. The result showed that the Blackfin flounder biomass will be maintained at 13,776 tons if the current fishing efforts (currently hp) level is set and maintained. If the fishing effort is reduced by 20%, it will increase to 17,091 tons in the future. The analysis on the economic effect of TAC showed that NPV will be the lowest at 1,486,410 won in 2038, 20 years after the establishment of 2,500 tons of TAC volume. If the TAC volume is set at 2,000 tons, NPV was estimated to be the highest at 2,206,522,000 won. In addition, the analysis on the economic effect of the policy to reduce the amount of fishing effort found that NPV will be 2,235,592,000 won in 2038, 20 years after maintaining the current level of fishing effort. If the fishing effort is increased by 10%, NPV will be the highest at 2,257,575 won even thoughthe amount of biomass will be reduced.

• The Journal of Fisheries Business Administration
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• v.42 no.3
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• pp.15-29
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• 2011

The Fish Stock Rebuilding Plan (FSRP) is evaluated as one of the most effective fisheries policies domestically and internationally. FSRP is a comprehensive fisheries policy, including target stock size, rebuilding period, application of management measures, and participation of fishermen. The performance outcomes of FSRPs have been partially evaluated for recommendation for stock rebuilding in Korea, while they are fully evaluated in other countries that have implemented FSRPs. The performance evaluation system for FSRP is very needed to enhance its effectiveness as one of fisheries policies. That is, the system where problems can be reconsidered, achieving targets can be evaluated, and the plan can be modified should be implemented. This study classified the performance evaluation of FSRP into the economic evaluation as a quantitative analysis and the policy evaluation as a qualitative analysis. In the economic evaluation, the sustainability of fishery resources, the stability of fishing business, the efficiency of fishery production, and efficient utilization of fishery resources can be considered. As analytical methods for the economic evaluation, the bioeconomic model, efficiency estimation model, the dynamic MEY model can be utilized. The qualitative evaluation is to assess the qualitative performances of FSRPs, including interviews and surveys with fishermen and fisheries experts. In the survey, many different items can be included by evaluation factors which are related to policies such as timeliness, transparency, effectiveness, etc. In addition, the study suggested the performance evaluation system and procedures for objective and efficient evaluation of FSRPs. In order to practically apply the developed performance evaluation model, the pilot project is needed. That is, from the application of pilot project, detailed research methods, effective procedures, and evaluation factors can be investigated.

• Environmental and Resource Economics Review
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• v.12 no.2
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• pp.299-325
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• 2003

This study uses Conrad's model(nominal fishing effort) of a fishery to analyze theoretically the effects of cost changes on fishing effort, harvest level, and stock size. Static and dynamic open access effects are also modeled present value maximizing scenarios through simulations, and compared an extended model, Cunningham's model(diminishing fishing effort). Results show that an increase in the unit cost of effort goes up the fish stock in static open access, but open access dynamics shows the exhaustion of fish stock as the unit cost of effort decreases. In conclusion, we can derive the optimal equilibrium of resource, given conditions and parameters, as well as utilize this comparative statics to efficient fishery management.

• The Journal of Fisheries Business Administration
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• v.42 no.3
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• pp.31-39
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• 2011

This paper attempts to extend such analysis to the rather more difficult problem of optimal management of transnational fish stocks jointly owned by two countries. Transboundary fish such as Mackerel creates an incentive to harvest fish before a competitor does and leads to over-exploitation. This tendency is especially poignant for transnational stocks since, in the absence of an enforceable, international agreement, there is little or no reason for either government or the fishing industry to promote resource conservation and economic efficiency. In the current paper I examine a game theoretic setting in which cooperative management can provide more benefits than noncooperative management. A dynamic model of Mackerel fishery is combined with Nash's theory of two countries cooperative games. A characteristic function game approach is applied to describe the sharing of the surplus benefits from cooperation and noncooperation. A bioeconomic model was used to compare the economic yield of the optimal strategies for two countries, under joint maximization of net benefits in joint ocean. The results suggest as follows. First, the threat points represent the net benefits for two countries in absence of cooperation. The net benefits to Korea and China in threat points are 2,000 billion won(${\pi}^0_{KO}$) and 1,130 billion won(${\pi}^0_{CH}$). Total benefits are 3,130 billion won. Second, if two countries cooperate one with another, they reach the solution payoffs such as Pareto efficient. The net benefits to Korea and China in Pareto efficient are 2,785 billion won(${\pi}^0_{KO}$) and 1,605 billion won(${\pi}^0_{CH}$) or total benefits of 4,390 billion won : a gain of 1,260 billion won. Third, the different price effects under the two scenarios show that total benefit rise as price increases.

• Environmental and Resource Economics Review
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• v.25 no.4
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• pp.517-543
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• 2016

This study aims to analyze economic impacts for changes in the oil cost of the anchovy boat seine fisheries in South Korea. As analytical approach, this study employs the exponential surplus production model to estimate the maximum sustainable yield and also utilizes the bioeconomic model to calculate changes in producer surplus of the anchovy boat seine fisheries under the open access responding to changes in the oil cost. As the result of analysis, increases in the oil cost due to prohibition of duty-free oil supply result in the negative impacts to the producer surplus of the anchovy boat seine fisheries in South Korea. However, increases in the oil cost of the anchovy boat seine fisheries lead voluntary exit to fishermen which can no more run their business. As a result, this study shows that fishing efforts of the anchovy boat seine fisheries reduce under the fishing efforts of the maximum sustainable yield ($F_{MSY}$) and stock of the anchovy increases.

• Environmental and Resource Economics Review
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• v.13 no.4
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• pp.717-734
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• 2004

This paper examined the statistical goodness-of-fit tests for biological growth model in bioeconomic analysis. Some authors estimated usually growth function for fish in the world. However, few studies have estimated growth equations for the bivalve species. Thus, this paper studied the common functional forms of fitting growth equations for cham scallops considering environmental factors and production styles. The following functional forms are considered: linear, log-reciprocal, double log, polynomial and linear with interactions. Results of fitting these various functional forms with real data are compared and evaluated using standard statistical goodness-of-fit tests. Results also indicate that log-reciprocal function is statistically the best fit to the real data. Therefore, the log-reciprocal function is decided the best function describing cham scallop biological growth and hence might be useful for economic evaluation(i.e., optimal harvesting time).