Hatching Periodicity and Growth
Rates of Black Crappies and White Crappies in Normandy Reservoir, Tennessee
Veronica A. Grear, Steve M. Sammons, and Phillip W.
Bettoli, Tennessee Cooperative Fishery Research Unit, Tennessee Technological University,
Box 5114, Cookeville, Tennessee 38505; Voice 931-372-3094; FAX 931-372-6257; E-Mail pbettoli@tntech.edu, ssammons@tntech.edu
Keywords: crappie, hatching periodicity, growth
rates
Age-0 black crappies Pomoxis nigromaculatus and
white crappies P. annularis were collected in cove samples from Normandy Reservoir,
a 1,307-ha flood control impoundment on the upper Duck River in south-central Tennessee.
Three coves were treated with rotenone (1.5 ppm active ingredient) during the first week
of August each year. Age-0 crappies were measured and weighed; otoliths were removed for
age analysis. In some years fish were subsampled for age analysis. Hatch dates and daily
growth rates were determined from the otoliths of age-0 crappies. Crappies hatched as
early as April 10 and as late as June 3. Hatch date distribution and length frequencies
were unimodal for each species in all years. Peak hatching preceded peak catch of larval
crappies in neuston samples by 7-10 d in each year. Growth for both species ranged from
0.4 to 0.8 mm/d and was positively related to hatch date. Crappies hatched earlier and
grew slower than largemouth bass and spotted bass collected concurrently in Normandy
Reservoir. Unlike largemouth bass, crappies never experienced bimodal hatching
distributions; earlier-hatched fish grew at slower rates than later-hatched fish, likely
due to warmer water temperatures experienced by later-hatched fish. Compared to largemouth
bass, growth and hatching of age-0 crappies appeared to be little affected by spring or
summer water-level events.
|