Lake Whitefish Diet, Condition, and Energy Density in Lake Champlain and the Lower Four Great Lakes following Dreissenid Invasions

Abstract

Lake Whitefish Coregonus clupeaformis support some of the most valuable commercial freshwater fisheries in North America. Recent growth and condition decreases in Lake Whitefish populations in the Great Lakes have been attributed to the invasion of the dreissenid mussels, zebra mussels Dreissena polymorpha and quagga mussels D. bugensis, and the subsequent collapse of the amphipod, Diporeia, a once-abundant high energy prey source. Since 1993, Lake Champlain has also experienced the invasion and proliferation of zebra mussels, but in contrast to the Great Lakes, Diporeia were not historically abundant. We compared the diet, condition, and energy density of Lake Whitefish from Lake Champlain after the dreissenid mussel invasion to values for those of Lake Whitefish from Lakes Michigan, Huron, Erie, and Ontario. Lake Whitefish were collected using gill nets and bottom trawls, and their diets were quantified seasonally. Condition was estimated using Fulton's condition factor (K) and by determining energy density. In contrast to Lake Whitefish from some of the Great Lakes, those from Lake Champlain Lake Whitefish did not show a dietary shift towards dreissenid mussels, but instead fed primarily on fish eggs in spring, Mysis diluviana in summer, and gastropods and sphaeriids in fall and winter. Along with these dietary differences, the condition and energy density of Lake Whitefish from Lake Champlain were high compared with those of Lake Whitefish from Lakes Michigan, Huron, and Ontario after the dreissenid invasion, and were similar to Lake Whitefish from Lake Erie; fish from Lakes Michigan, Huron, and Ontario consumed dreissenids, whereas fish from Lake Erie did not. Our comparisons of Lake Whitefish populations in Lake Champlain to those in the Great Lakes indicate that diet and condition of Lake Champlain Lake Whitefish were not negatively affected by the dreissenid mussel invasion.

Received March 15, 2012; accepted November 5, 2012

ACKNOWLEDGMENTS

We thank Mark Ebener (Chippewa Ottawa Resource Authority), Tim Johnson, Jim Hoyle, and Lloyd Mohr (Ontario Ministry of Natural Resources), Chuck Madenjian and Steve Pothoven (U.S. Geological Survey, Ann Arbor, Michigan) for providing their unpublished Lake Whitefish data from the Great Lakes. We give special thanks to Ted Strang (U.S. Geological Survey, Oswego, New York) for sample processing and assistance with the bomb calorimeter. We also thank Steve Smith, Elias Rosenblatt, Neil Thompson, Josh Ashline, Kevin Osantowski, Lindsay Schwarting, and Joanna Hatt for assistance in the field and laboratory, and Richard Furbush, Joe Bartlett, and Rebecca Gorney for assistance with fish collection. Ruth Mickey and Alan Howard provided statistical advice. Funding for this project was provided by NOAA through the Lake Champlain Sea Grant Project. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This article is Contribution 1724 of the U.S. Geological Survey Great Lakes Science Center.