Kitchell, J. Center for Limnology, Univ. of Wisconsin, kitchell@macc.wisc.edu
Harvey, C. Center for Limnology, Univ. of Wisconsin,
Johnson, T. Ontario Ministry of Natural Resources,
Mason, D. Purdue Univ.,
Aydin, K. Univ. of Washington,
Ebener, M. Chippewa-Ottawa Treaty Fisheries,
Hansen, M. College of Natural Resources,

 
SUSTAINABILITY OF THE LAKE SUPERIOR FISH COMMUNITY: AN ECOSIM MODELING ANALYSIS OF OPPORTUNITIES AND CONSTRAINTS
 
Restoration of the native fish community has been and continues to be a goal for the Laurentian Great Lakes. In Lake Superior, restoration of the native lake trout populations is well underway and now deemed one of the major success stories in fisheries management. However, the ecosystem now contains an assemblage of exotic species such as sea lamprey, rainbow smelt and Pacific salmon (chinook, coho and steelhead). Those play an important role in defining the constraints and opportunities for management. We employed a combination of a mass balance model (Ecopath) and a food web model (Ecosim) to evaluate ecological consequences of future, alternative management actions. Forage fish abundance is a key constraint for all salmonids in Lake Superior. Smelt and Mysis play vital roles in sustaining the current trophic structure. Competition between native lake trout and exotic salmonids is asymmetric. Reductions in salmon stocking have only modest benefit for lake trout stocks while increased fishing on lake trout produce substantial potential increases in Pacific salmon yields to the recreational fisheries. The deepwater or siscowet race of lake trout has become very abundant and plays a major role in food web structure but offers little potential for restoration of a valuable commercial or recreational fishery. Even a combination of strong management actions (no fishing, no salmon stocking, etc.) cannot restore lake trout to pre-fishery and pre-lamprey abundances. Instead, management must accept the ecological constraints due, in part, to the presence of exotics and choose alternatives that sustain public interest in the resources while continuing the gradual progress toward restoration.
 
Day: Wednesday, Feb. 3
Time: 03:45 - 04:00pm
Location: Sweeney Center
 
Code: SS09WE0345S