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mixing of water in both areas so virtually the entire water column can support fish during some part of the year. So, as populations of non-game fish continue to increase, further declines (indicated in Figures 2, 3, and 4) in rainbow fisheries may be expected. The canyon area (average depth 60 m) favors production of game fishes because of lack of littoral area. The declining rainbow stock in the canyon is probably influenced by increasing mackinaw stock. The rapid increase suggested (Figure 2) for white suckers reflects location of net sets; nets must be set in what littoral area is available and catches reflect what is caught in the limited shallow water zones. These data suggest a continued decline in rainbow fisheries accompanied by, at least, a stable and perhaps increasing population of mackinaw and brown trout. Whether the evolution of the Flaming Gorge fishery will follow the pattern of smaller, shallower Klicava Reservoir (Europe) is unknown, but is seems likely that the northern two-thirds (relatively shallow with extensive shoreline) of the reservoir will continue to favor production of non-game fishes. The fisheries in the canyon will likely continue to favor trout because of lack of littoral areas but the rainbow may continue to decline because of increasing population of larger predator fishes, mackinaw and brown trout. We have considered introductions of various forage fishes (planktivores) such as threadfin shad, pond smelt, Mississippi silversides and brook silversides to depress Utah chub populations and provide a small pelagic food fish for rainbow trout. Where threadfin have become established in western reservoirs (Lake Powell, Lake Mead), it has been used by rainbow. However, introductions of other species elsewhere have caused depletion of game fish populations while contributing to the further development of a trophy fisheries (Hanson 1976, personal communication). Perhaps what is needed is an indifferent predator as suggested by Holcik and Pivnicka (op. cit.), but that would be accompanied by a reanalysis of the Flaming Gorge fisheries because trout are certainly not indifferent predators. 28