Lake Francis Case, a Missouri River reservoir : changes in the fish population in 1954-75, and suggestions for management /

Changes in fish abundance and species composition were mainly a result of poor reproductive success caused by water-level fluctuations during the spring and early summer, and physical changes in the shoreline environment. Fish reproduction was most successful in years when the reservoir was filled in the spring and a nearly constant level was maintained through July. Survival and growth would probably improve if the pool drawdown in the fall were reduced. Fish abundance could be increased if water-level management conformed more closely to requirements for fish reproduction. However this is only possible in some years because of the multipurpose function of the reservoir. In consideration with this restraint, a 3-year cycle in pool level management was recommended with a relatively low level maintained for two years to encourage growth of shoreline vegetation followed by a high level during the 3rd year, through July, to encourage successful spawing and survival of young of a number of important game species, as well as increase the abundance of forage fishes and invertebrates.Studies conducted during the first 23 years of impoundment of Lake Francis Case indicated that fish abundance in the early 1970's was about half of that in the late 1950's. Of 39 species collected, 12 were abundant in the 1950's and 8 in the 1970's, but only 4 were abundant throughout the impoundment period.Bibliography: p. 11-12.Changes in fish abundance and species composition were mainly a result of poor reproductive success caused by water-level fluctuations during the spring and early summer, and physical changes in the shoreline environment. Fish reproduction was most successful in years when the reservoir was filled in the spring and a nearly constant level was maintained through July. Survival and growth would probably improve if the pool drawdown in the fall were reduced. Fish abundance could be increased if water-level management conformed more closely to requirements for fish reproduction. However this is only possible in some years because of the multipurpose function of the reservoir. In consideration with this restraint, a 3-year cycle in pool level management was recommended with a relatively low level maintained for two years to encourage growth of shoreline vegetation followed by a high level during the 3rd year, through July, to encourage successful spawing and survival of young of a number of important game species, as well as increase the abundance of forage fishes and invertebrates.Studies conducted during the first 23 years of impoundment of Lake Francis Case indicated that fish abundance in the early 1970's was about half of that in the late 1950's. Of 39 species collected, 12 were abundant in the 1950's and 8 in the 1970's, but only 4 were abundant throughout the impoundment period.Mode of access: Internet