Initial Poststocking Mortality, Oxytetracycline Marking, and Year-Class Contribution of Black-Nosed Crappies Stocked into Tennessee Reservoirs

Abstract

Initial poststocking mortality, oxytetracycline mark persistence, and year-class contribution were evaluated for black-nosed crappies, a morphological variant of the black crappie Pomoxis nigromaculatus, stocked into Tennessee reservoirs during 1997–1999. Average initial poststocking mortality was low (x = 13%, N = 44). Lake temperature and the difference between lake and hauling tank water temperatures were significant in explaining variability in arcsine-transformed mortality estimates; however, the variability explained by these factors was low (R2 = 0.15). Oxytetracycline immersion was a highly effective marking tool; 97–100% of all crappies treated were marked, and 99% of the marks were visible 36–110 weeks after marking. All control otoliths were correctly scored as unmarked during the evaluation, and mortality rates did not differ between marked and unmarked crappies. Year-class contribution was variable across reservoirs and was highest in Normandy Reservoir (34–93% at ages 1–3). Contribution at ages 1 and 2 was 11–24% in Woods Reservoir. Stocking did not supplement the crappie population in Lake Graham. Black-nosed crappies made up a significant portion (>50%) of the crappies harvested by anglers in Center Hill Reservoir 3 years after stocking was initiated. Conversely, black-nosed crappies made up a relatively small percentage (≤12%) of the crappies harvested in Cherokee Reservoir in the 4 years after initial stocking.