Food habits, age and growth, and forage value of the alewife in Watauga Reservoir, Tennessee

In 1976, the alewife (Alosa pseudoharengus) was stocked in Watauga Reservoir, Tennessee, by the Tennessee Wildlife Resources Agency in an attempt to strengthen the forage base. To assess ecological impacts of the introduction, both food habits and age and growth of alewives were evaluated along with food habits of game fishes and age and growth of walleye. Alewives and game fishes were collected using electrofishing, horizontal and vertical gill netting and "borrowing" from angler creels.

Alewives fed primarily on cladocerans, copepods, and crustacean eggs in both littoral and limnetic regions. Piscivority in alewives was not found to be a significant problem due to the small size of age 2 alewives (103 mm) and the low occurrence of piscivority (0.6%). The alewife population was composed of three age classes (0+, 1+, and 2+). Back-calculated lengths were 70 mm at annulus I and 103 mm at annulus II. No significant differences between sexes were found with back-calculated lengths or with the length-weight relationship (α = 0.05).

Alewives contributed to the diets of walleye, smallmouth bass, crappie, rainbow trout, and Ohrid trout. Only in largemouth bass, were there no identifiable alewives found, though unidentified clupeids (alewives and/or gizzard shad) occurred. Age classes of wall-eye identified by the collection procedures included age 2 through 6. Back-calculated growth at annuli were I-183 mm, III-315 mm, III-395 mm, IV-442 mm, V-475 mm, and VI-534 mm. Females were found to be significantly heavier than males of the same length and longer at age than males, by length-weight relationships and back-calculated lengths, respectively. Condition factor of walleye was 1.04 indicating sufficient forage for the population size of walleye in Watauga Reservoir. Predator-prey analyses supports a hypothesis that the alewife population in Watauga (maximum size 131 mm) is available to the piscivorous game fishes in the system.