A biotelemetry study of spring and summer habitat selection by striped bass in Cherokee Reservoir, Tennessee, 1978

Habitat selection of 3l adult striped bass was monitored by temperature sensing ultrasonic and radio transmitters in Cherokee Reservoir, Tennessee, from March through October 1978. This study sought to corroborate summer data obtained by Waddle (1979) in 1977 and to examine mechanisms of habitat selection by observing establishment of the summer distribution. During the spring and early summer months, March through early July, the striped bass ranged throughout the study area in the downstream half of the reservoir. Temperature preference ranged from 10.5 C in March to 15.8 C in May and corresponded to the warmest temperatures available at 1 to 3 m. Fish stayed near the bottom at the preferred temperatures throughout the whole study, and no individuals were observed in open water. Movement rates of up to 2.6 km/day were estimated and rates of 1 km/day were common in the spring.

As the temperatures increased during the summer, the striped bass selected temperatures in the range 15.5 to 25.0 C at depths to 8 m and more. By late July they were apparently avoiding low dissolved oxygen (D.0.) concentrations (<3 mg/e) near the bottom of the main reservoir and epilimnion temperatures greater than 22 C, and they moved into cool, oxygenated spring or creek channels (refuges). These refuges, approximately 4% of the total reservoir area, were less than l0 m deep and had temperatures of 15 to 25 C and D.0. concentrations of >5 mg/e. Temperatures selected remained between 15.5 to 25.0 C within these refuges, and little movement within or migration between the refuges was observed. Low movement rates of 0 to 25 m/day within these refuges

iv occurred. The rates of the few migrations between refuges could not be estimated. Tagged fish moved out of the refuges 3 to 4 weeks after the fall overturn when reservoir temperatures approximated 22 to 24 C. Some indication of an ontogenetic change in temperature preference was seen. Older striped bass seemed to prefer cooler temperatures (16 to 20 C) than the younger striped bass (20 to 23 C).