In this study, based on the basic theory model ¢wGordon-Schaefer model is used to discuss the equilibrium levels for yellowfin tuna in the Western and Central Pacific of open access (OA) and present value maximization (MPV). And then to compare the catches and the stocks on the two model¡¦s equilibrium value, the result shows the management of yellowfin tuna in the Western and Central Pacific tend to MPV model, the regional fisheries organization (RFMO) to detect the implementation of the measures (MCS) is significant; in addition, use sensitivity analysis and then to understand the changes on the stocks and the effort quantities effected by varying different parameters. In OA, if you want to get effectively maintain the sustainability of the stocks, should be considered to reduce the price and the catch coefficient, increase the cost per unit of effort to control; in MPV, we can understand that the catch coefficient and the intrinsic growth rate have a bigger influence in the effort quantities; Finally, by simulating the catches and the stocks, that if it can continue to effectively manage fishery by MCS in the future, the catches and the stocks of yellowfin tuna will tend to balance the value of MPV, and so on, not only resources effective use of maximum profit and maintaining our fleet of ocean-going business interests, but also resources can be sustainable.

In this research, using the statistic catch data of northwest pacific saury from the Overseas Fisheries Development Council of The Republic of China between 2004 to 2007 to conduct an resource assessment on pacific saury. First of all, calculate and compare the equilibrium level of open access fishery and the net present value maximization fishery. And then, using the northwest pacific saury statistic catch data from the Food and Agriculture Organization of The United Nations between 2005 to 2007 for the simulation analysis of resource of pacific saury, and the results simulated with the two fishing grounds of the equilibrium value for comparison. The results showed that the problem of depletion of the resource does not exist. The final, assumption that the value of parameters are changing in the range of reasonable in order to understand the impact of the changing in the fishery resource of the stock and effort. Collate and analyze the results, and expect that the results can be a management reference for the management of the northwest pacific saury fisheries.

In this research, using the statistic catch data of northwest pacific Ommastrephes bartrami from the Overseas Fisheries Development council of The Republic of China between 1997 to 2007 and FAO between 1982 to 2007 to conduct and resource assessment on Ommastrephes bartrami. First of all, calculate and compare the equilibrium levels of open access fishery and present value maximization fishery, then evaluate the stock size of Ommastrephes bartrami and compare the equilibrium levels of two models with the statistic readings, the result shows the Ommastrephes bartrami has no sign of depletion. By using sensitivity analysis, we understand the changes on the effort and stock effected by varying different parameters. Finally, by simulating the stock size of open access fishery and present value maximization fishery, we find that unrestricted developing can end up the resources, but Ommastrephes bartrami will receive sustainable development, if it can be effectively managed. And expect that the results can be a management reference for the management of Ommastrephes bartrami fisheries.

The study is based on Gordon-Schaefer model, using statistic data from Western and Central Pacific Fishery Commission to estimate the resource stock of Albacore between 1960 and 2009. Compare the equilibrium levels of open access model and present value maximization model with the real data, and the result shows that the real stock is close to the equilibrium of present value maximization model. The thesis uses sensitivity analysis to understand the impact of the changed parameters on stock and effort, and by using real examples to understand the impact of the changed situation on stock and effort. Finally, by simulating the stock of open access fishery and present value maximization fishery and government management nowadays fishery. The result shows the stock of government management fishery is higher than the stock of the present value maximization fishery, and the stock both are closed. The management is conservative and effective, hence the management will make the profit maximize and the resource continue forever to develop.

This study used the Gordon-Schaefer model to discuss the equilibrium levels for bigeye tuna in the Western and Central Pacific of open access and present value maximization. And then to compare the catches and the stocks on the two model¡¦s equilibrium value, the result shows the management of bigeye tuna in the Western and Central Pacific tend to present value maximization model. Following that, this paper did sensitivity analysis to understand the impact of the changed parameters on stock size and effort. Finally, using simulation analysis on open access model and present value maximization model. In open access model, the result shows that resources will face extinction crisis if the fishery is not controlled well. In the present value maximization model, the bigeye tuna would be sustainable management. This result is valuable for the fishery management authorities to maintain the development of fishery and cherishing ocean resources at the same time.

This study used the Gordon-Schaefer model which was extended to Open Access (OA) model and Present Value Maximization (MPV) model to discuss the equilibrium levels for bigeye tuna in the Western and Central Pacific Ocean by purse seine fishery data. I compared the catches and the biomass with the two model¡¦s equilibrium value, and the result showed that the operating mode of bigeye tuna in the Western and Central Pacific Ocean tended to the MPV model, and the bigeye tuna resources were diminishing. In addition, the sensitivity analysis was used in order to understand the impact of various parameter changes on the two fisheries model¡¦s equilibrium value. In the OA model, the change of the price, the cost per unit effort and the catch coefficient would have greater impact on the equilibrium biomass. In the MPV model, the equilibrium biomass was sensitive to the change of the environmental capacity. Finally, in order to understand whether the management of the Western and Central Pacific Commission (WCPFC) was effective, I used simulation analysis in accordance with the catches restriction and effort restriction management strategies. The result showed that the catches restriction strategy which WCPFC established was still not proper enough. It must cut a large number of catches immediately and continue for some time enough to make the resource recover. The effort restriction strategy could make good effect on the bigeye tuna resource recovery.

Abstract This study used the Gordon-Schaefer model to do resource economic analysis on the South Pacific albacore fishery in 1967-2007 . Evaluated the equilibrium standard of open access model and present value maximization model, and then compared them with the real data. The results indicates that the fishing yield, resource stock, effort and catch-per-unit-effort of south Pacific albacore is close to the equilibrium level of present value maximization model after year 2002, which means the South Pacific albacore fishing is under appropriate development. Following that, this paper did sensitivity analysis to understand the impact of the changed parameters on stock size and effort. Finally, using the simulation analysis on open access model and present value maximization model. In open access model, the result shows that resources will face extinction crisis if the fishery is not controlled well. In present value maximization model, the albacore fishery would sustainable management. This result is valuable for the fishery management authorities to maintain the development of fishery and cherishing ocean resources at the same time.

This research is based on Gordon-Schaefer model, using the statistic data from the FAO between 1983 to 2007 to conduct an assessment on Argentine shortfin squid, Illex argentinus. First of all, calculate and compare the equilibrium levels of open access fishery and present value maximization fishery, then evaluate the stock size of Illex argentinus and compare the equilibrium levels of two models with the statistic readings, the result shows that Illex argentinus has no sign of depletion, but it has not yet reached the best status for development. By using sensitivity analysis,we understand the changes on the effort and stock effected by varying different parameters. Finally, by simulating the stock size of open access fishery and present value maximization fishery, we find that unrestricted developing can end up the resources, but Illex argentinus will receive sustainable development, if it can be effectively managed.

Abstract Because the number of sharks is decreasing , the problem has been concerned in recent years. In this paper , I conduct a research about the shark bycatch problem¡Ataking the target specie of bigeye tunas and the bycatch specie of sharks as the research objects . Initially I collect from 2000 to 2007 Atlantic bigeye tuna and shark catches datas for resource assessment.and then making comparasion with resource equilibrium values of open access fishery model and net present value maximization fishery model. it is found during the period it has showed a upward trend for bigeye tuna resources¡Abut it has not showed the bigeye tuna resources achive the optimal level. It has showed a diminishing trend for shark resources, the result shows the resources will face extinction crisis if the fishery is not controlled well. Then, doing sensitivity analysis to understand the effects of exogenous parameters to bigeye tuna and shark catches, resources and efforts. Finally, facing with the sharks bycatch problem , discussing the effect of improved fishing gears on sharks bycatch control by doing the sensitivity analysis of fishing hook cost and bycatch coefficient to shark resources and catches¡OFrom the results , it shows that no matter affecting the fishing hook cost or bycatch coefficient , the amount of shark can be reduced effectively by adopting improved fishing gears.