基于贴现率的东黄海鲐鱼动态生物经济模型分析

A Dynamic Bio-Economic Model Combined with Discount Rate for Chub Mackerel in the East China Sea and the Yellow Sea

渔业资源是一种可再生资源,其资源的可持续利用不仅与其种群大小有关,而且还与作业规模、单位作业的经济成本和贴现率等有关。传统生物经济模型通常忽视了贴现率对渔业资源配置的影响。本文根据1999年-2009年中、日、韩三国在东黄海捕捞的鲐鱼渔获量以及生产成本数据,结合贴现率和渔获价格等数据,构建基于贴现率的东黄海鲐鱼动态生物经济模型。结果表明,贴现率为10%～30%时,短期利益占长期利益的10%～20%,渔获价格在(2327～4654)元/t时,可保证鲐鱼渔获量低于最大可持续产量,从而有效地控制捕捞强度,确保鲐鱼资源的可持续利用。

Fishery resources are renewable. Previous studies were primarily focused on theoretical investigation into bio-economical models of fishery resources. Sustainable use of its resources is not only related to its population size, but also related to fishing scale, fishing cost per unit of effort, and discount rate. In the traditional bio-economical models, only two extreme cases, i.e., the discount rates are zero or infinity, are considered. However, the impact on fisheries resources by the discount rate is often ignored. In this paper, a dynamic bio-economical model was established using fishery data and fishing economic data from China, Japan, and South Korea during the period 1999-2009, and considering the effect of the discount rate on resources exploitation of Chub mackerel （Scomber japonicus） in the East China sea and Yellow sea. The dynamic bio-economical model was designed to estimate the stock and yield under different management goals. An appropriate discount rate is used to determinate the number of D accepted by current society, which is the proportion of immediate interests. The discount rate-supply curve was plotted for investigation into the development and management of fishery resources carried out in the catch prices. Results show that the fishery was generally overcatched. The declining resources would make the social and ecological benefits decrease. The discount rate ranged between 10% and 30%, and the short-term interests accounted for 10%-20% of the long-term interests. When the catch prices are 2327-4654 Yuan per ton, it can ensure that the catch of Chub mackerel is less than the maximum sustainable yield （MSY）, and the fishing effort can be effectively controlled for the resources of Chub mackerel. If the fishery of Chub mackerel becomes a scarce resource in fish markets, the prices would go up due to an increasing demand. The developers might extend the production scale for financial gain. With the rapid development of catch, the base of ecological resources has been weakened. The fishery of Chub mackerel may be destroyed when the fishing intensity is beyond the limits of regenerative capacity of fishery. Therefore, the landing price of Chub mackerel is affected by the discount rate indirectly. With rising discount rate, the price is declined, and the fishing effort could be reduced and the catch can thus be under the MSY. The amount of fishing business loan fund can be limited by increasing the discount rate, and fishing effort and fishery revenue could also be decreased. A change in discount rate can be adjusted by the government. The change is in form of receiving rent from fishery to control the fishing effort. Meanwhile, consumption rate of fishery resources could be slowed down by rent capture in fishery of Chub mackerel and increasing the cost of the direct exploitation of fish. In general, the sustainable development level of Chub mackerel can be elevated by the strategic management above. This study provide some guidance for scientific management of fishery resources.