White crappie summer movements and habitat use in Delaware Reservoir, Ohio
habitat, adult, habitat preference, night, light intensities, Gradient, active, slope, marking, structures
Journal or Book Title
North American Journal of Fisheries Management
Adult white crappies (Pomoxis annularis) were radio-tagged to determine summermovement patterns and habitat preferences in Delaware Reservoir, a 532-hectare flood controlreservoir in central Ohio. Movements of 29 white crappies (271–352 mm total length) increased atdusk, peaked at night, declined at dawn, and remained low throughout the day. Day and nightmovements averaged 17 and 47 m/h in 1988 and 9 and 28 m/h in 1989, respectively. Movementwas significantly greater (P . 0.05) between 2200 and 0200 hours than it was for all time periodsbetween 0600 and 2000 hours in 1988 and between 0800 and 2200 hours in 1989. Peakmovements occurred when measurable light intensity approached zero. Greater movements alsooccurred during times of high barometric pressure and during times of little change in barometricpressure. Transmitter signal strength, calibrated to estimate fish depth, indicated that whitecrappies were generally deeper during the day (5.4 m) than at night (4.3 m). Ten high-use areaswere mapped. Features common to all areas included a relatively steep bottom gradient (6–22°)and the presence of structure in the form of tree stumps, logs, and large rocks. The fish wereusually located over steep bottom gradients. The median daytime home range was 0.63 hectaresin 1988 and 0.49 hectares in 1989; the nighttime home range was 1.25 hectares in 1989,significantly larger (P = 0.002) than the day home range that year. Day and night movementsrevolved around a central location. Crappie anglers frequently fish in shallow areas during the daywhen fish are least active and have relocated in deeper water over steep slopes. Improvingsummertime angling may require marking favourable white crappie areas to attract fishermen, aswell as enhancing available habitat with structures to increase fish densities.