Nutrient content of Clupeid forage fishes in Tennessee reservoirs

Gizzard, threadfin, and hybrid shad, and alewives were collected from Cherokee, Dale Hollow, and Old Hickory Reservoirs, Tennessee, from January 1984 through December 1984. Collections of fish were analyzed for proximate composition (moisture, ash, protein, and lipids) and gross energy content. Overall ranges of nutrients for all collections were: moisture, 69.7 - 84.9%; ash, 12.0 - 32.5%; protein, 45.4 - 79.1%; lipids, 3.3 - 31.5%; and gross energy, 3.92 - 6.06 kcal/g. Changes in protein, ash, and moisture percentages within an age class of a species were primarily the result of changes in lipid percentage. In general, lipid content increased through the summer, peaked during the fall, and declined during the winter. Seasonal variations in feeding level and reproductive condition, and differences in reservoir productivity, age, and sex were causes of variations in body composition within a species. Proximate composition and gross energy content of the clupeids examined were similar; however, young-of-year and adult alewives exhibited the highest individual gross energy values in their respective age classes.

Hybrids of gizzard and threadfin shad comprised 3.2% of shad collected from Cherokee Reservoir from August 1983 through August 1984. They exhibited intermediate and high morphometric and meristic values when compared with the parent species.