Predicted Effects of Global Climate Change on Fishes of Minnesota Lakes

According to global climate change models, e,g. that from the Columbia University Goddard Institute for Space Studies (GISS), Minnesota's mean air temperature will increase by an annual average of approximately 4.0 'C if atmospheric C02 doubles. This is likely to have many environmental consequences, including changes in lake water temperatures and dissolved oxygen concentrations which in turn are likely to affect fish populations. This interaction between climate parameters, lake water quality parameters and fish populations has been investigated through model simulations of Minnesota lakes. Previous results of this study were summarized in September 1991 (Stefan et al., 1991, 1992). Specifically the description of fish habitat is extended herein to include lake benthic area, in addition to lake volume used in the previous report. The findings are as follows: After the projected climate change, good growth habitat bottom area (GGHA) and good growth habitat volume (GGHV) will be reduced for coldwater fish. In contrast, GGHA and GGRV will be increased for coolwater and warmwater fish. Coldwater, coolwater and warmwater fish habitat will change approximately by the same percentage in terms of GGHA or GGHV. The reduction in good growth habitat area or volume for coldwater fishes will be about twice as high for southern Minnesota as it will be for northern Minnesota lakes. The increases for cool water and wa.rmwater fishes will be three times greater for northern Minnesota lakes than for southern Minnesota lakes. The models I and assessment techniques employed to derive these conclusions can serve as templates for analysis of projected climate change impacts in other regions. i