Demographic Analyses

Using the information resulting from PSRC life history studies, we will begin to examine the population dynamics of commercially exploited elasmobranchs from the ENP. We will model demographic parameters, including net reproductive rate, generation times, intrinsic rates of increase, and stable age distributions of Pacific sharks using life history table analysis and age-based Leslie matrices. We will also conduct sensitivity and elasticity analyses to determine the most sensitive life stages of select species of Pacific sharks. Deterministic and stochastic demographic models will be developed in an effort to best predict the population status and future trends of Pacific sharks. These approaches are ideally suited to sharks and rays due to the lack of or uncertainty in life history information that is generally available for most species. Demographic analyses are being coordinated with and methodologies are being further developed by PSRC colleague, Dr. Henry Mollet. Species currently being assessed include the diamond stingray (Dasyatis dipterura), pelagic stingray (D. violacea), and shortfin mako (Isurus oxyrinchus).