Hatching periodicity, hatching distributions, and daily growth rates of age-0 white crappies in response to hydrology and zooplankton densities in Normandy Reservoir, Tennessee

Steve M. Sammons, Phillip W. Bettoli, and Veronica A. Greear,
Tennessee Cooperative Fishery Research Unit, U. S. Geological Survey, Box 5114, Tennessee Technological University, Cookeville, TN 38505, U.S.A. (931) 372-6205, FAX (931) 372-6257, E-mail: ssammons@tntech.edu

Age-0 white crappies Pomoxis annularis were collected from 1994 to 1998 in cove samples from Normandy Reservoir, a 1,307-ha flood control impoundment on the upper Duck River in south-central Tennessee. Crappies were collected in every year buts 1995. Age-0 crappies were measured and weighed; otoliths were removed and hatch dates and daily growth rates were determined for the aged fish. Crappies hatched as early as 10 April and as late as 3 June. Hatch date distributions and length frequencies were unimodal in all years. First hatch date and mean hatch date of white crappies were positively correlated to the first day the reservoir achieved full pool. Growth ranged from 0.32 to 0.83 mm/d. Growth did not appear to be affected by density of crappie larvae, but was weakly correlated with cladoceran and copepod densities. White crappies hatched earlier and grew slower than largemouth bass Micropterus salmoides and spotted bass M. punctulatus collected concurrently. Unlike largemouth bass, white crappies never experienced bimodal hatching distributions; earlier-hatched fish grew at slower rates than later-hatched fish in three of four years, likely due to warmer water temperatures experienced by later-hatched fish. Growth of age-0 white crappies appeared to be little affected by spring or summer water-level events, but may have been influenced by hatch date and zooplankton density.