Age and Growth of Grass Carp in Lake Guntersville, Alabama

A total of 139 grass carp (Ctenopharyngodon idella) of unknown ploidy were collected by bowfishing during 1993 and 1994 in Lake Guntersville, Alabama. Ages were determined from sectioned otoliths (lapilli), then age-specific total lengths were back-calculated using scales of known age. Mean back-calculated total lengths of grass carp were 334, 627, 768, 852, 896, 895, 920, 965, and 973 mm at ages 1 through 9, respectively. A length-to-weight relationship was calculated as: weight (g) = 0.00000519 x total length mm3-14, r2 = 0.92. A von Bertalanffy growth equation described growth as: Lt = 954 (i-e-0.590(t-0.257)), r2 = 0.99. Growth averaged 2.33 kg/year through age 4; subsequent growth was much slower, averaging 0.71 kg/year. Growth in Lake Guntersville was slower and more variable than in the Santee Cooper reservoirs, South Carolina. Occurrence of 3 age classes not stocked by Tennessee Valley Authority (TVA) precluded mortality estimates.

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