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amount of time elapsed since birth (Gustaveson et ale 1984). Striped bass yoy have consistently been collected in large numbers near the inflow and near Glen Canyon Dam with only modest numbers found in midlake areas. Stocking was curtailed in 1979 to allow the magnitude of natural reproduction to be assessed. It was evident within two years that reproductive success of large proportions was taking place. It is thought that current created by entrained water released through penstocks of Glen Canyon Dam is detected by striped bass causing attraction and spawning aggregations. Prespawning staging of mature fish commonly have been found near the dam, and striped bass eggs have been collected with tow nets within 6 km of the dam. Unlimited reproduction of striped bass dramatically increased population size and placed an overwhelming predatory burden on threadfin shad which is the only pelagic clupeid forage fish present in Lake Powell. Trawling results showed that threadfin shad were eliminated from reservoir open water zones for most of the 1980's. Adult shad (>150 mm) were able to survive in sanctuaries in warm turbid backwaters where striped bass adults were unable to enter because of thermal limitations and where juvenile striped bass were not large enough to consume them. Absence of pelagic shad caused a decline in physical condition of adult striped bass and eventual starvation in some years. During initial striped bass introductions (1974-1979), the creel limit was 2 fish. with discovery of natural reproduction the creel limit was raised to 4 fish in 1983. A peak in striped bass harvest and rapid decline in physical condition led to another limit increase to 10 fish in 1984. Small average total length of striped bass in the low shad years of the 1980's led to a 1990 increase in creel limit to 20 fish, in attempt to harvest small fish. Finally, an abundant 1991 striped bass year class perched on the edge of starvation resulted in the removal of the creel limit altogether in 1993. Regulations were further 6