CLIMATE CHANGE IMPACTS ON FRESHWATER RECREATIONAL FISHING IN THE UNITED STATES

We analyzed the potential impacts of climate change on stream suitability for freshwater fish assemblages in the United States. We quantified the projected changes in stream water temperatures, stream flow, and areal extent of suitable habitat resulting from a range of projected changes in temperature and precipitation. Based on the projected shifts, we estimated potential economic impacts associated with changes in freshwater recreational fishing. Using a geographic information system, we developed a spatially explicit modeling framework of grid cells organized into 2,099 8‑digit hydrologic unit code (HUC) polygons for the coterminous United States. Projected temperature and precipitation changes associated with climate change were obtained for 2030, 2050, and 2100 and three future emissions scenarios representing low, moderate, and high emissions. We then generated a grid of projected water temperatures using regional air/water temperature regressions. Habitat suitability was derived from the value of the lowest average monthly water temperature within a HUC compared to a model-calibrated maximum water temperature tolerance of coldwater and warmwater fish guilds. Although projections vary somewhat by emissions scenario and year, in general the spatial distribution of coldwater fisheries is predicted to contract, being replaced by warm/coolwater and rough fisheries. As expected, these projected changes are more pronounced with increasing time and emissions. To estimate the potential economic impacts of predicted habitat changes on recreational fishing, we used a national-scale economic model of recreational fishing, updated with current data. Using projected losses in fishing days, multiplied by per-day values derived from the current economics literature, we estimate that the total present value of estimated national economic losses to freshwater recreational fishing from 2009 to 2100 will range from US$81 million to $6.4 billion, depending on the discount rate assumed, and the emissions scenario.