عنوان مقاله [English]
Since the fisheries sector is one of the important economic sectors that plays a significant role in providing income and employment for the coastal people of the country. In order to maintain the stability of aquatic resources and access to numerous economic, biological, social and planning goals in aquatic resources, it seems inevitable (Rezaat Kish and Badam Firoz, 2017). One of the important goals in fisheries management is to maintain the process of fishing and harvesting from Aquatic resources and sustainable fishing levels. In order to measure the achievement of goals in the process of sustainable development, a series of indicators should be used. Fisheries management for sustainable development is a multi-dimensional activity that should be investigated in a wide area that requires information and data, or indicators other than fish stocks and fishing activity (Wang et al., 2014). Increasing awareness by economic experts, formulating policies, principles, rules and regulations and also expression of scientific models and strategies appropriate harvested and productivity of natural resources, suitable field for the growth and development of other sectors (industry, commerce, agriculture and services) provided and will lead to a stable outlook in country.
One of the most important management tools and solutions that can play a constructive role in the sustainability of natural resources is the use of advanced economic models. For this purpose, in this research, after presenting a method to estimate the net value of resource extraction, a dynamic model was designed to optimize the extraction values. The Lagrange coefficient method was also proposed as another solution in this research. This method is essential for optimizing resources that are harvested in the long term.
Estimating the present value of net benefits from natural resources
The present value of net benefits (NPV) in economics is one of the standard methods for evaluating economic projects. In this method, the cash flow of income and expenses is discounted to the daily rate based on the time of occurrence of income or expenses. In this way, in the cash flow, the time value of spending or earning income is included. Net present value in natural resource economics is used to estimate the present value of resource extraction.
The exploitation of natural resources due to rapid population growth and meet the basic human needs of growing and developing. This growth in addition to, production technology developed and harvesting of resources in large scale, emphasis to sustainable economic and environmental activities. According to the vulnerable renewable and non-Renewable resources of countries require that exploit them, for removal existing needs in a manner to be achieved that these resources remain sustainable for coming generation. Achieving this goal requires strong leadership on utilization of existing resources in nature. In this regard, the use of dynamic models for determining optimal amount of harvest and right resource management in the short term and long time periods, necessary to proving to be true this goals and the important role in assist to farmers. For the design of the dynamic optimization model was used Lagrange multiplier method In Chabahar area of Sistan and Baluchestan province in 2021. Excel software was used to solve the model.
Today, the exploitation of natural resources is growing and developing due to the rapid growth of the population and meeting the basic human needs. This growth is in such a way that in addition to the development of the technology of production and harvesting of fishery resources on a large scale, it also emphasizes the economic and environmental sustainability of the activities. In this research presented model to determine optimal amount harvest fishery resources in future periods. This model due to changes in discount rates in various periods of time was to be able to allocate resources in a way that in all periods have maximum profit and net benefits. And causes reduce speed to empty store resource and assist to sustainable of resource. The results showed that the storage of a fishery affected by factors such as the amount of storage, the harvest of the source, the discount rate, rate of return on investment and saving rates is a renewable source. Also the result showed that harvest fish from a fishery over 10 periods with fixed-rate of about 0.05 percent, and started from the second year Total value of net benefits in this case is the equivalent of 15.29 million rials. While that after implementing dynamic planning model amount of fish of resource changed of 0.05 to 0.124. After optimization amount harvest of resource, total net present value by model dynamic planning to estimate 22.75 million rials that indicating increase net present value 7.46 million rials regard to present state. Also the net present value of benefits (NPV) of fish harvested during the 10 consecutive periods reduced to increase discount rate and with discount rate cut has increased. In other words, the relationship between changes in the present value of net benefits and the discount rate indirect or reverse. In addition, by increasing and decreasing the rate of return on investment, increase and decrease the amount of storage. This suggests the existence of a direct relationship between changes rate of return on investment and save the fish is over 10 consecutive periods. And relationship between the rate of return on investment and change of net present value of harvesting fish during 10 consecutive periods.
In the end, is recommended the use of dynamic programming models due to its flexibility and ability to calculate time series data in order to allocate renewable natural resources during consecutive periods harvesting of resources. The use of these models to determine the appropriate and schedule program for the harvest of natural resource renewable, cause to protection and stability this resources in long term. In the end, the use of dynamic planning models is recommended due to their flexibility and the ability to calculate time series data in order to allocate renewable natural resources during successive periods of resource extraction. The use of these models, in addition to determining a suitable and scheduled program for the extraction of renewable natural resources, causes the preservation and sustainability of these resources in the long term.