Abstract: Recreational fisheries represent complex socio-ecological systems. Angler effort can be driven by local or global social factors, ranging from expanding human populations, shifting social norms to the dynamics of fish populations. Yet in many cases, recreationally targeted species lack fisheries-independent monitoring, and angler catch and effort metrics remain the best available data to infer information about population status and trends. Here, examining one of the most iconic recreational fisheries in the world, steelhead trout (Oncorhynchus mykiss) in British Columbia (BC) Canada we 1) quantify spatio-temporal shifts in angler effort and catch rates, and 2) assess the utility and limitations of recreational catch per unit effort (CPUE), as an index of spawner abundance.
Large scale patterns of catch and effort were assessed in over 200 steelhead-bearing streams during a 60-year period that included major shifts in abundance of several stocks. We discovered that effort varies through time, and regionally between urban areas and remote systems. Steelhead fisheries in some regions have collapsed completely, while angler effort has expanded in other regions. For example, angling effort has decreased to a small fraction of historical levels across the collapsing interior Fraser River stocks, whereas effort has increased substantially in more northern systems like the Skeena.
These data reveal a dramatic spatial restructuring of this important recreational fishery. However, there are relatively few long-term monitoring programs for steelhead which creates major uncertainties. Thus, we quantified the relationship between angler CPUE from the recreational fishery and fisheries-independent abundance indices in 15 streams. The strength of the relationship between CPUE and abundance varied by stream and by area and is affected by several properties of the data (e.g., sample size, survey method) and stock characteristics (e.g., ecotype, stocking). In some cases, CPUE does appear to be a viable indicator of abundance.Taken together, these findings showcase the collapse and expansion of a globally renowned recreational fishery, and highlight the challenges, opportunities and limitations of using recreational fishery data to monitor the status of this at-risk species.
