Climate Change Impacts on Stream Temperature and Flow: Consequences for Great Lakes Fish Migrations

Background/Need: Having achieved consensus that Wisconsin’s air and water are warming under global climate change (http://www.wicci.wisc.edu/), a key challenge now is to understand the breadth of ecological impacts. Wisconsin citizens benefit greatly from the services provided by water resources, and fisheries have particular cultural importance. Present understanding of climate warming impacts on fish is based largely on thermal tolerances; effects on breeding behavior and success are poorly known. Many important fish species migrate from the Great Lakes into tributaries to breed every year, and potential cues for these migrations (temperature, flow) are being altered by climate change. However, historical rates of change in migration timing are unknown, the abiotic triggers of migrations remain uncertain, and ecosystem responses to fish migrations have not been determined. This project addresses needs for both scientific and public understanding of climate-driven shifts in the timing of Great Lakes fish migrations, and their ecological implications.
Objectives: Objective 1: Quantify the historical timing of Great Lakes fish migrations into Wisconsin tributaries. Objective 2: Monitor the current migration timing along a latitudinal gradient of Wisconsin tributaries to identify threshold temperature and flow levels that trigger the onset of migrations. Objective 3: Predict how the timing of migrations is likely to shift with future climate change, and evaluate the implications from species to ecosystems.