U.S. Geological Survey

Chinook Salmon Oncorhynchus tshawytscha, along with other salmonines, were introduced in Lake Michigan dur-ing the 1960s to provide a viable sport fishery and biocon-trol for nuisance Alewife Alosa pseudoharengus populations (Tody and Tanner 1966). Chinook Salmon subsequently became an effective Alewife predator (Stewart and Ibarra 1991) and the focus of a popular, multibillion-dollar sport fishery. Since their introduction, population levels of Chi-nook Salmon have been maintained through stocking prac-tices to accomplish two conflicting management goals: (1) control of Alewife abundance, and (2) maintenance of a Chinook Salmon sport fishery dependent on available Ale-wife forage (Jones et al. 1993). In response to these objec-tives, managers have attempted to maintain salmon abun-dance at high levels within what can be sustained by available prey fishes, primarily Alewife