Lake Superior supports a variety of commercially, recreationally, and/or ecologically significant, self-sustaining species including lake whitefish, lake trout, lake herring, deepwater ciscoes, yellow perch, walleye, rainbow smelt and three species of sculpins. It is the only Great Lake that has maintained a majority of its native species, and during the past 20 years has undergone progress toward restoration of lake trout, lake whitefish, and lake herring. Restoration of the Lake Superior ecosystem is a long-term goal of State, Federal, Provincial, and Tribal resource management agencies in the United States and Canada. The major objective of that goal is to reestablish native fishes that occupy different trophic levels such as lake trout (top predator) and ciscoes (planktivores). The task of restoration of native species has been complicated by the intentional introduction of exotic predators, such as the Pacific salmon, that have become naturalized throughout the basin. In addition and in contrast to these planned introductions, sea-lamprey, rainbow smelt, ruffe, round goby, zebra mussel, the spiny water flea, and other aquatic species, that represent several trophic levels, have been unintentionally introduced and also have become naturalized. Based on food habit studies, the food web of Lake Superior now includes a diversity of species and species interactions unknown in its ancestral state. Annual bottom trawl surveys conducted by the U.S. Geological Survey's Great Lakes Science Center represent the only lake-wide inventory of most of the 73 fish species in Lake Superior. State, tribal, and federal fishery management agencies have relied on annual assessments in the nearshore U. S. waters of the lake in spring, and assessments of Chequamegon Bay in summer, because these have provided the best quantitative descriptions of the status and trends of prey and young predator fishes across space and through time. Those assessment results have been used to measure progress toward rehabilitation and restoration of fishes in the lake. Thus, this study will help the Great Lakes Science Center meet its mission by continuing to provide data and information to help scientifically manage the living resources of the Great Lakes ecosystem. The objective of this continued work is to continue to provide annual estimates of recruitment, relative abundance, age structure, and size structure of important prey fishes (especially lake herring, rainbow smelt, slimy sculpin, spoonhead sculpin, deepwater sculpin, and ninespine stickleback) in Lake Superior and Chequamegon Bay.

Progress of this study as of January, 2001:
Forage fish abundance is a key constraint for all salmonids in Lake Superior. Rainbow 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 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. Siscowet lake tout has become very abundant and plays a major role in food web structure, bu offers little potential for restoration of a valuable commercial or recreational fishery. Even a combination of strong management actions cannot restore lean 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.

Lake Report: Status and Trends of Prey Fish Populations in Lake Superior, 2004