A Preliminary Study Of Management Strategy Evaluation Of Yellowfin Tuna In Indian Ocean

Yellow-fin tuna(Thunnus albacares) is an economic species whose production is the highest among tuna species in high sea. In Indian Ocean, the yield of yellowfin tuna stays high in China‘s longliner. At present, fisheries resources are depleting worldwide and the sustainable development of yellow-fin tuna resources is more and more important. How to protect its resources has become an international concern.Sustainable use of fisheries resources is always on the basis of scientific management. There are many management strategies to achieve management objectives. Owing to fishery is a complex system, different management strategies have different performances. What‘s more, there are uncertainties which can lead to potential mismanagement of fisheries resources. Thus the precautionary approaches are applied to avoid the risk of mismanagement. In addition, unlike scientific experiments, fishery management in reality is an irreversible process, and it is impossible to implement several management strategies on a fishery simultaneously and compare their performances. How to choose the best management strategies to achieve the management objectives is the key issue in the current international fisheries management, as well as the challenge the fishery scientists and managers have to face.Management strategy evaluation is a systematic framework, which simulate the fish stock and ecosystem via computer simulation, and evaluate or test different management strategies effectively according to management objectives. MSE can solve the disadvantages of traditional fisheries, such as the uncertainties and improve the possibilities of successful fishery management.Yellowfin tuna in Indian Ocean is one of the very few target species in the high seas with further development for China‘s fisheries fleet. There is an urgent requirement to strengthen the research on its fishery resources. Although Indian Ocean Tuna Commission has assessed the resources several times, there are great uncertainties in determining the status of the resources because of the different data errors and model errors existing. In this study, I developed a management strategy evaluation system for the yellowfin tuna in Indian Ocean to evaluate different scenarios of management strategies and their uncertainties. And then raise an optimal management strategy for of the yellowfin tuna fishery in Indian Ocean.In this paper, I firstly introduced the theory of MSE, as well as the resources and management status of yellowfin tuna in Indian Ocean. Furthermore, evaluate different management strategies of yellowfin tuna by using MSE. Main study methods and results are as follows:(1) Prior to reviewing the management status and previous studies of yellowfin tuna in Indian Ocean, the target biological reference points are set Bmsy and Fmsy which are used as management objectives in MSE.(2) I take advantages of biological and fisheries parameters in IOTC reports and the published citations incorporated in the MSE analysis, the software MSE 4.0 in NOAA fishery toolbox was used to set up management strategy evaluation system. The total of 25 different management strategies from 2010 to 2020 was set in the implement simulation management with consideration the uncertainties by comparing and evaluating the performances of different management strategies in MSE simulation quantitatively, an optimal management strategy was developed for this tuna fisheries management.(3) According to the result, the optimal management strategy is MS7, ie, F is 0.1 and SSB is 600,000 tons. Under this management strategy, the annual SSB is above management objection SSBmsy, average year fishing mortality is below management objection Fmsy. Average year catch is 440,139 tons and the annual fluctuation of the fishing mortality is the smallest, which means the quota-based fisheries can be accepted easily.(4) The simulation result is similar to the analysis of IOTC including the high catch. This suggested that yellowfin tuna resources in Indian Ocean is relatively high in the next 10 years. But IOTC should strengthen the management and conservation of yellowfin tuna under good resource status, and try to avoid overfishing and overfished fisheries because of increasing fishing vessels. In addition, the stock assessment should be carried out as plan, in order to ensure the implement of the right management strategy.This study not only provided decision support for yellowfin tuna in the Indian Ocean,but also provided a reference of scientific management for other types of tuna resources. In terms of theory, this study might extend the area of fishery resources research, and explored new method for fisheries management system in China. In terms of practice, this study provided theoretical support and reasonable advice for the sustainable development of yellowfin tuna fisheries resources in Indian Ocean.