Age and growth of largemouth bass and temporal and spatial movements of fishes in thermally enriched Flint Creek Cooling Reservoir.

摘要

The one year water temperature mean (upper 4 m), of Flint Creek Reservoir was 29{dollar}spcirc{dollar}C. This indicates that thermal effluent can affect up to 100% of the reservoir to depths in excess of four meters. The average horizontal thermal gradient, from the hot water outlet to the make-up water outlet by the dam, was 8{dollar}spcirc{dollar}C. Vertical thermal gradients were observed with a maximum of 20{dollar}spcirc{dollar}C in one meter. The laboratory thermal preferendum for largemouth bass (30.0{dollar}spcirc{dollar}C) was in agreement with that reported in the literature. Catch-per-unit-effort and mark-recapture data indicated that largemouth bass were highly mobile and made local and intrareservoir movements consistent with their thermal preferendum. Large adult bass did move less than the juveniles, except in summer when the adults abandoned their territories to migrate to the thermal refuge stations. Black bullheads also concentrated in the summer thermal refuge stations that received an influx of cooler water. The channel catfish used in the laboratory study did not have a well defined final thermal preferendum though upper and lower avoidance temperatures were in agreement with those reported in the literature. Channel catfish largely avoid the summer thermal refuge stations and were commonly collect in the main reservoir in summer.; Analysis of largemouth bass scales, including those from 48 tagged and recaptured fish, revealed that many scales had more 'annuli' than possible for the age of Flint Creek Cooling Reservoir. The mark-recapture data indicated the formation of one supernumerary annulus per year for most bass. Time of formation of true and supernumerary annuli and the causitive factors are discussed.; Growth of bass from this reservoir greatly exceeded that reported for thermally unaltered reservoirs of Northwest Arkansas, due to the existence of a nearly year-round growing season, a result of thermal enrichment. The relationship between the ratio of electric power output to reservoir surface area and growth of fish was evaluated with reference to published data on cooling reservoirs.