The Effect of Annual Water Level Management on Population Trends of White Crappie in Elk City Reservoir, Kansas

To improve a marginal white crappie (Pomoxis annularis) sport fishery in a 1,800 hectare Kansas reservoir, a management plan for water level manipulation was devised to increase the population. The essence of the plan was to increase the water area during the spawning season to stimulate natural reproduction, while flooded vegetation increased the amount of spawning habitat. The effect of this procedure was significantly (P < 0.05) related to an increase in the relative year-class strengths of white crappie during a 5-year period, as compared to year-class indices measured 5 years previously. However, the hectare-days of flooded vegetation during the spawning season were not significantly related to the increase in crappie numbers, but may have been overshadowed by environmental conditions that limited reproduction or recruitment of the white crappie. Fluctuations in water levels during the crappie spawning season had a significant (P < 0.05) but negative relationship on crappie year-class strengths. Also, floodwater releases were negatively correlated with year-class strengths at the 0.001 level of significance. Water level management can be an effective management tool when unregulated conditions severely restrict crappie reproduction and recruitment.