بهره برداری از یک گونه منفرد به وسیله آستانه سیاست های مدیریت

Continuous time models of single exploited populations usually generate outcomes expressing a dependence of yield and economic items on harvest intensity. In this work it is shown that a known threshold policy is able to generate yield and related economic items that do not depend on harvest intensity, but rather on the values of the population threshold itself and the species intrinsic parameters. It is argued that since this result can be carried over to other models of single species dynamics, it may have significant implications in the management and conservation of exploited populations.

Single as well as multispecies harvesting has been a subject of theoretical and empirical studies [21]. As to single species exploitation, fixed quota and fixed proportion harvest policies have been applied in the management of natural populations both in continuous and discrete time settings. Besides the two strategies named above, threshold policies have also been proposed as a means of population management [19]. Basically, threshold policies consist of two or more thresholds that dictate different harvest strategies according to the population level with respect to the considered thresholds. In this work it is shown that threshold strategies of exploited populations can generate sustainable yield and related economic items with harvest intensities (e.g., fishing effort) that would otherwise cause species extinction if they were continuously applied. To some extent, this result can be carried over to other continuous single species models and therefore may have significant implications in the management of exploited populations regarding economic and conservation issues.