Population Characteristics and Angler Harvest of White Crappies in Four Large Missouri Reservoirs

Populations of white crappie Pomoxis annularis were studied at four Missouri reservoirs to determine population characteristics and develop techniques to improve the quality of fishing. Trap-netting in October was used to sample white crappies in Stockton, Pomme de Terre, Lake of the Ozarks, and Wappapello reservoirs. At all four reservoirs, trap-net capture rates for year-classes that were age-2 or older were significantly correlated with estimated harvests the following year. Growth rates were consistently rated satisfactory; age-3 white crappies averaged 9 in or longer at all of the reservoirs except Wappapello, where they averaged 8.6 in. Trap-netting and creel surveys both indicated that the populations consisted mainly of young white crappies; few age-4 and older fish were captured in nets, and more than 90% of the harvest consisted of ages 1–3. Exploitation rates, determined from tag returns from white crappies tagged at Stockton and Pomme de Terre, were estimated to be about 60% for fish 9 in and longer (age 3 and older). Total annual mortality averaged about 50% for age-2 white crappies and 80% for ages 3 and older. Annual harvests of white crappies were variable because of fluctuations in year-class strength, but they averaged about 22 fish/acre at each reservoir. Mean lengths of harvested white crappies, which were frequently less than 9 in, also varied because of fluctuations in year-class strength and were smaller when age-2 fish dominated the harvest. Large-reservoir white crappie populations with satisfactory growth and high angler exploitation have the potential to provide larger fish in the creel if restrictive regulations that reduce the harvest of age-1 and age-2 fish were imposed. Such regulations also should reduce the effect of fluctuations in year-class strength, because the populations would contain a higher percentage of older fish.