Recreational fisheries as a driver of salmonid population conservation

O_LIThe need to monitor and protect biodiversity has never been greater, yet resources are often constrained economically. The ecosystem service paradigm could promote nature conservation while sustaining economic activity and other societal benefits, but most efforts to assess biodiversity-ecosystem service (B-ES) links have focused on diversity measures, with little attention on how species abundance relates to the magnitude of ES provision.\nC_LIO_LIHere, we utilised four national scale, multi-decadal, Atlantic salmon (Salmo salar) datasets to investigate links between juvenile density, the abundance of returning adults, and two measures of recreational angling provision: rod catches and angling effort.\nC_LIO_LIRecreational rod catches only tracked juvenile density and returning adult numbers in catchments where juvenile and adult numbers were decreasing, implying important early-warning of ES decline. In contrast, angling effort declined consistently through time.\nC_LIO_LISynthesis and applications. These data illustrate i) the difficulty in measuring ES in ways that explicitly relate human resource use to nature conservation, and ii) the need for better quantification of populations at all life stages that determine ES provision, particularly in species where long-distance movements bring exposure to multiple global pressures. We suggest additional opportunities (e.g., monitoring of smolts, eDNA and citizen science initiatives) to facilitate conservation efforts and increase capacity to monitor ecosystem service sustainability.\nC_LI