Evaluation of a Power Plant Reservoir As A Holding Area For Paddlefish Brood Stock

Twenty paddlefish (Polyodon spathula) released into the Big Stone Power Plant boiler make-up reservoir were monitored to determine growth, condition, and food habits. In addition, fish and zooplankton populations were sampled and chemical and physical parameters measured to determine the potential of the reservoir as a holding area for paddlefish brood stock. Paddlefish captured during the first year after their release into the boiler make-up reservoir averaged 2.2 kg body weight increases and 59 mm eye-fork length increases. Condition factors of captured paddlefish also increased during this period from 1.26 to 1.49. Paddlefish food in the reservoir consisted almost entirely of crustacean zooplankton. Cyclopoid copepods were the most abundant food item found in stomachs sampled, making up over 60% of the total food organisms consumed by numbers. Volumes of food in paddlefish stomachs sampled ranged from 0 to 90 ml. Feeding activity was greatest during April, May, and July. Feeding occurred at lower levels or ceased during June, August, September, October, and November. Cyclopoid copepods had the highest mean selectivity index and Diaptomus spp. the lowest mean selectivity index. Mean selectivity values of other food items were all near 0, indicating that paddlefish had no preference for or against them