Estimating the value of threatened species abundance dynamics

Conservation spending aimed at helping threatened species lacks information on the marginal benefits of increases in the abundance of threatened species that occur at different points in time. This paper develops an empirical approach combining a choice experiment and a structural model to estimate two key parameters in a dynamic willingness-to-pay function: the current marginal benefit of increases in threatened species abundance and the rate implicitly used to discount future marginal benefits. An application to a threatened Coho salmon along the Oregon coast illustrates the method. We find that the public values a one-year marginal increase in Coho abundance of 1000 fish from $0.08 to $0.19 per household with a discount rate for future increments in salmon abundance of 2.1%. We apply these results to an instantaneous and permanent marginal increase in salmon abundance of 0.79% resulting from a policy change in one watershed and show this marginal change can generate over $63 million in present value of social marginal benefits to the greater Pacific Northwest region. Results provide direct evidence that conservation activities that achieve immediate abundance gains for a threatened species (or prevent immediate losses) produce significantly higher benefits than activities that gradually achieve the same abundance gains.