Habitat Use by Striped Bass in Relation to Seasonal Changes in Water Quality in a Southern Reservoir

Abstract

Adult striped bass Morone saxatilis (n = 61; 597-914 mm total length) were captured by hook and line throughout Lake Murray, South Carolina, and by electrofishing in the Greenwood Dam tailrace and upper Saluda River above Lake Murray, implanted with temperature-sensitive radio transmitters, and tracked biweekly. During late winter-early spring, striped bass were concentrated in the upstream portions of the reservoir. By midsummer, they were primarily located in the lower embayment of the reservoir, but several fish remained in the tailrace of the upstream dam as well as in a thermal refuge in the Saluda River. After the reservoir began to cool in fall, fish dispersed from the lower embayment and moved upstream toward the headwaters of the reservoir, where they had been captured the previous spring. Several fish returned to locations within 10 m of their original capture locations. Mean movement rates were lowest in winter and summer and highest in spring and fall. Low movement rates in summer were associated with a severe reduction of suitable habitat. In addition to the standard biweekly sampling, a 7.5-km² section of the lower embayment of Lake Murray was searched every 2 h over a continuous 48-h period from 10 to 12 August 2000. During this period, striped bass were observed to use the same areas on a seasonal basis as they did on a diel basis. However, mean hourly rates of movement were greater than the movement rates calculated for the normal 2-week interval between samples. Changes in location between biweekly samples may not indicate displacement but rather only randomly chosen locations in normal use areas.