How to choose? A bioeconomic model for optimizing river barrier mitigation actions

Abstract River infrastructure can cause adverse impacts on fish populations, which, in turn, compromises the ability of river ecosystems to provide a range of ecosystem services. In this paper, we present a methodological approach to assess the potential economics costs and benefits of river connectivity enhancement achieved through removal and mitigation of fish dispersal barriers. Our approach combines the results of a stated preference study for nonuse values of rivers and statistical models of fish population responses to barrier mitigation actions within an integrated bioeconomic optimization framework. We demonstrate the utility of our methodology using a case study of the River Wey catchment in southeast England, which contains over 650 artificial barriers. Our results reveal the presence of benefit-cost trade-offs which can form the basis for river barrier mitigation policy development. In particular, we find that benefits exceed costs in the River Wey for all levels of investment in barrier mitigation considered (£2.5 to 53.4 M). Furthermore, from an economic efficiency standpoint, a total budget of approximately £22.5M allocated to barrier mitigation would maximize net societal benefits derived from anticipated increases fish species richness and abundance.