**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**
Whitefish Natural Mortality Coordination Workshops
Mark P. Ebener 1 and Michael T. Arts2
1Chippewa Ottawa Resource Authority, 179 West Three Mile Road, Sault Sainte Marie, Michigan USA 49783, mebener@lighthouse.net
2National Water Research Institute, Environment Canada, 867 Lakeshore Road, PO Box 5050, Burlington , Ontario Canada L7R 45A6, michael.arts@ec.gc.ca
Abstract
We held three annual workshops in 2004 to 2006 to assess the magnitude of natural mortality (M) in exploited lake whitefish populations of the Great Lakes, to understand how it varies, and the potential causes of that mortality. Twenty-one individuals gave oral presentations at the three workshops and there were 1-3 plenary talks given at each workshop by invited researchers from throughout North America and Europe. E vidence was presented that M does vary temporally and these temporal changes can be monitor ed using m ark-recapture and telemetry techniques . We recommend that agencies estimate M on a stock-by-stock basis using these two techniques . M changes with life stage of fish and the primary causes of death change with life stage, but there is insufficient information to rank these causes . We suspect that essential fatty acids play a key role in the health of lake whitefish and impinge on M . We suggest examples of laboratory-based studies that might assess the role of essential fatty acids in M . Traditional methods of expressing condition factor of fish, such as Fulton’s K, are not useful in describing health of lake whitefish. We recommend a visceral fat index and percent water in muscle plugs as useful indicators of fish condition and health. W e propose eleven research priorities and identify numerous laboratory studies that should advance scientific knowledge of natural mortality and fish health.