A method of evaluating white bass (Morone chrysops) populations sampled with gill nets during fall in Missouri's large reservoirs was developed by establishing objectives for growth, size structure, and age structure parameters. Growth objectives were 300 and 350 mm mean total lengths for age-1 and -2 white bass in reservoirs where gizzard shad (Dorosoma cepedianum) are the primary prey, and 330 and 380 mm in reservoirs where threadfin shad (D. petenense) are the primary prey. Objectives for size and age structure were determined by modeling population structures of white bass with acceptable growth and intermediate total annual mortality rates (about 40%-50%). Objectives for size structure (percentages of white bass ?age 1 that were also ?300 mm and 380 mm) were 65%-85% and 5%-25% for gizzard shad prey reservoirs, and 80%-100% and 30%-50% for threadfin shad prey reservoirs. The objective for age structure (percentages of fish ? age 1 that were ? age 4) was 10%-20% for all reservoirs. Using these criteria and objectives, fishery managers can evaluate white bass populations and determine problem areas when populations consistently fail to meet objectives. Results of the evaluation can be used to implement specific management practices to correct problems, or to justify the need for more-detailed studies that will identify the causes of the problems.
