**The information in the completion report for this project is currently under review by the Canadian Journal of Fisheries and Aquatic Sciences. The title, authors, and abstract for this completion report are provided below. For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**
The challenge of inferring possible effects of climate change on Great Lakes fisheries: models that link habitat supply to population dynamics can help
Michael L. Jones1,4, Brian J. Shuter2, Yingming Zhao2, Jason D. Stockwell1,3
1Department of Fisheries and Wildlife
13 Natural Resources Building
Michigan State University
East Lansing, MI, 48824, USA
2Department of Zoology
25 Harbord St.
University of Toronto
Toronto, ON, Canada
3Current address: U.S. Geological Survey
Lake Superior Biological Station
2800 Lakeshore Drive East
Ashland, WI 54806
Future changes to climate in the Great Lakes basin may have important consequences for fisheries. Recent assessments suggest that global and regional temperatures have risen substantially during the past century, as has regional precipitation to a lesser degree. In the Great Lakes water temperatures have risen and duration and extent of ice cover has lessened. Projections from Global Circulation Models indicate further warming and increases in precipitation in the region during the 21st century. We present new evidence that water temperatures have risen in western Lake Erie, particularly during summer and winter in the period 1965-2000, particularly in. Forecasts from GCMs coupled with basin physical models suggest lower annual runoff, less ice cover, and possibly lower lake levels in the future. The certainty of these forecasts is low, however. We argue that assessment of the likely effects of climate change on fish stocks requires an integrative approach which considers the combined effect of change to several components of habitat. Most assessments to date have emphasized the effect of increases in water temperature alone. We recommend the use of mechanistic models that couple habitat conditions to population demographics to explore integrated effects of climate-caused habitat change. We use a model for Lake Erie walleye to show that the combined effect of plausible changes in temperature, river hydrology, lake levels, and light penetration, can be quite different from that which would be expected based on consideration of only one of these factors. We review evidence that climate change is likely to be an important stressor for Great Lakes fishes, present new evidence that climate-driven habitat changes are already occurring in the Great Lakes, and discuss challenges associated with forecasting the consequences of alterations to future climate. We argue that mechanistic models that link plausible habitat change to fish population dynamics have an important, and underutilized, role in assessing potential climate-change effects on fishes and in guiding future research.