An approach to determine the extinction risk of exploited populations

Abstract

We propose a method for assessing the persistence of species where the resource is harvested. Four sustainability measures are employed, namely a population measure, a harvest measure, a profitability measure and a catchability measure. These are used to assess the sustainability of two natural resources representing terrestrial and aquatic species, namely White Rhino (Ceratotherium simum) and South African abalone (Haliotis Midae) species, respectively. The framework is used to evaluate these two resources against relevant local and international protected species listings. The results show that the proposed framework produces a more conservative approach to listing threatened species, consistent with the precautionary principle. The framework provides a way of conducting a precautionary assessment of extinction risk under conditions of exploitation, across a range of aquatic and terrestrial species. Once developed, we also apply this framework to seven additional species using a scenario analysis. The results highlight the importance of taking into consideration institutional factors under conditions of overexploitation.