Evaluation of a 254-mm Size Limit and Supplemental Stocking as Management Strategies for Tennessee Reservoir Crappie Fisheries

Daniel A. Isermann*, Phillip W. Bettoli, and Steve M. Sammons
Tennessee Cooperative Fishery Research Unit Tennessee Technological University 205 Pennebaker Hall Box 5114 N. Dixie Ave. Cookeville, TN 38505, phone: (931) 372-3094 fax: (931) 372-6257, E-mail: dai7422@tntech.edu

Key words: crappies, size-limit, stocking, oxytetracycline, growth

Effects of a 254-mm size limit on crappie harvest in ten Tennessee reservoirs was simulated using a Beverton-Holt equilibrium yield model. Simulations indicated that size limit impacts varied across reservoirs and that potential yield benefits were not always realized with the restriction. At low levels of conditional natural mortality (CM = 30%) size limits positively impacted yield in all reservoir simulations; however, a 229-mm limit provided higher predicted yields than the current 254-mm limit in some scenarios. The effectiveness of size restrictions at CM = 40% was variable and generally increased with increases in exploitation. Size limits did not positively impact yield when CM was 50%. On average, crappies recruited to the 254-mm limit at age 3 and crappie growth was variable among systems. Relationships between crappie growth and species composition, annual mortality, and reservoir characteristics were analyzed. In fall 1997 and 1998 age-0 crappies were marked with oxytetracycline and stocked into four reservoirs. Marking efficacy ranged from 98 to 100%. Stocked crappies represented 90% of the age-1 crappies collected in rotenone samples from Normandy Reservoir in August 1998. Age-1 stocking contributions in 1999 will be presented for Woods, South Holston, and Normandy Reservoirs.