U.S. Environmental Protection Agency Report
April 1995, EPA #220-R-95-004
This study focuses on freshwater fishing in rivers and streams as a starting point for estimating potential impacts to recreational fishing from climate change. As greenhouse gases accumulate in the atmosphere and alter the climate, rising temperatures, changes in precipitation, and changes in other weather patterns are likely to affect ecological processes and ecosystem services. Among those systems and organisms affected may be a variety of fish species. The potential negative impacts to fish species and the popularity of recreational fishing led to an EPA sponsored research project which examined the potential impacts of climate change on fish species survival, and the effect on future recreational fishing opportunities.
Significant losses of cold water fish were projected to result from climate change, with the greatest losses occurring in the southern border of a species natural range, where baseline temperatures were closest to thermal tolerances. Cold water species were most affected, but significant losses were also predicted for the cool water guild and for individual members of warm water and rough guilds (e.g., crappie, rock bass, smallmouth bass and white sucker).
Projected losses of cold water fishing opportunity resulting from climate change were fairly significant when considered in isolation, but the economic losses may be partially offset by the opportunity for anglers to fish in lakes and impoundments or to turn to other types of fishing (cool, warm, and rough). Two equilibrium Global Climate Change Models projected estimated annual damages of $95 million and $85 million while in the other two models gains in cool and warm water fishing offset losses in cold water fishing, resulting in annual benefits of about $80 million each. The GFDL transient 2050 scenario projected annual losses of $320 million, the largest welfare losses of all the scenarios. The transient 2100 scenario predicted cold water acreage losses twice as large as those losses predicted by 2050, but the losses are offset slightly by gains in cool, warm, and rough acres, resulting in an annual loss of $266 million. When alternative modeling methods were employed, or assumptions relaxed, estimated damages increased substantially.
Two analytical tools were used to conduct the assessment: a thermal model and an economic model. The thermal model estimates the effects of temperature changes on habitat conditions within different geographic areas and the subsequent effect on the ranges of fish species. The economic model uses measures of habitat changes estimated by the thermal model to project changes in the frequency and type of recreational fishing. The thermal modeling predicted significant losses of cold water fish, with the greatest losses in the southern border of a species' natural range. Cold water species were most affected, but significant losses were also predicted for the cool water guild and for individual members of warm water and rough guilds (e.g., crappie, rock bass, smallmouth bass, and white sucker).