Potential Changes to Great Lakes Fish Assemblages in a Warming Climate

Warming climate threatens substantial change to fish habitats and populations. Quantifying the response of habitats and fish abundance to changes in climate conditions helps us measure that risk and plan for those changes. Great Lakes Regional Aquatic Gap Analysis models have successfully predicted stream water temperatures and fish abundances throughout the US Great Lakes Basin. We used a sensitivity analysis of the neural network models applied in New York State to simulate the effects of climate change on stream water temperature and fish habitat. Mean annual air temperature was incremented by 0.1°C, 0.5°C, 1.0°C, and 2.0°C. Preliminary results indicate that 5% - 11% of streams will shift to a higher temperature class with a mean annual air temperature increase of 0.1°C, while as much as 42% of streams may shift to a warmer temperature class when mean annual air temperature increases by 2°C, and the trend is non-linear. Some streams were also predicted to shift to a cooler temperature class; it is unclear if this is a model artifact or if a combination of environmental conditions exist that would result in cooler streams. Associated changes in optimal habitat extent for stream fishes will be discussed. These model responses suggest that small changes in mean annual air temperature could affect habitat and fish in the Great Lakes.