Growth and food habits of introduced stizostedion hybrids in Cherokee Reservoir, Tennessee

Growth and food habits of young-of-year and yearling Stizostedion hybrids stocked in Cherokee Reservoir, Tennessee, were examined from July 1983 to December 1985. Growth was excellent throughout the study and hybrids averaged 296 and 442 mm at ages 1 and 2, respectively. Both young-of-year and yearling hybrids attained 90% of their annual growth by December. Condition factors (K) of hybrids increased with age (0.62- 1.17), while relative weights (W_r) were within the acceptable range (95-105) for all but three months of the first two years following introduction. Both condition indices decreased sharply during the spring and summer. Reduced abundance of appropriate-sized shad following winter and sub-optimal temperature/dissolved oxygen characteristics may negatively affect hybrids during this period. Hybrids began consuming fish immediately following stocking, with shad being the most important food item for both young-of-year and yearlings during each year of the study. Insects, primarily chironomids and Hexagenia nymphs, were consumed by hybrids during the spring and summer, but were a minor component of the total hybrid diet. Non-shad fishes were frequently collected in forage samples, but occurred rarely in the diets of hybrids. Results from prey-predator length relationships suggested that there was a decrease in the abundance of appropriate- sized shad during the late spring.