Abstract We used a Beverton–Holt equilibrium yield model to predict the effects of four different length limits (203, 229, 254, and 279 mm) on harvest of black crappies Pomoxis nigromaculatus and white crappies P. annularis in Weiss Lake, Alabama. The current 254-mm length limit took effect in 1990, and we wanted to assess length limits with more recent data. We documented angler harvest and catch rates before and after the initiation of the size limit. Size structure, growth, and total mortality were estimated for fish collected with trap nets and by electrofishing. Growth was above average compared with other reservoirs in the state with fish reaching 254 mm in about 2.4 years. Estimates of total annual mortality ranged from 51% to 64% and annual exploitation was 33%, but because of uncertainty, a wide range of fishing and natural mortality rates were incorporated into the simulations. Three years after the length limit took effect, angler harvest and catch of crappies increased two–four fold and the si...