Summer habitat selection by striped bass, Morone saxatilis, in Cherokee Reservoir, Tennessee, 1977

Summer habitat selection patterns of 18 adult striped bass (Morone saxatilis) in Cherokee Reservoir were monitored with externally attached temperature-sensing acoustic or radio transmitters from June through September 1977. Mortalities of adult striped bass in this reservoir were hypothesized to be related to high summer temperatures and low dissolved oxygen (DO). Summer home ranges of most fish corresponded to cool, oxygenated spring or tributary effluents feeding shallow, submerged channels (less than 10 m deep) located in the lower reservoir. The inhabited areas or refuges differed from non inhabited areas by maintaining temperatures less than or equal to 22 C and DO concentrations greater than 5 mg/liter. Total water hardness, pH, and water transparency were not significantly different among refuges and non inhabited areas.

Movement of fish outside refuges occurred more frequently and for longer periods during June when the summer pattern of high temperatures and low DO was less severe. Fish experienced temperatures between 15 and 27 C with mean temperatures of individuals ranging from 18.5 to 22.0 C. Several tagged fish migrated outside the refuges and selected the lowest available temperature, generally near 21 C, even though DO concentrations at these temperatures were 3 mg/liter or less. Long-term survival of tagged and nontagged fish outside refuges was undetermined because no fish were tracked outside a refuge for more than 12 days without being lost. This study indicates that temperature strongly influences the behavior of striped bass and that adults of this species may have a thermal preferendum of approximately 21 C.