Biology and Exploitation of Paddlefish in the Missouri River below Gavins Point Dam

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Abstract
Life history of paddlefish P. spathula was investigated in the unimpounded, unchannelized stretch of Missouri River below Gavins Point Dam, South Dakota-Nebraska during 1972-1979. Females were longer and heavier than males of similar age. The von Bertalanffy growth equation for males and females was Lt = 84.9 {1- exp[-0.133(t + 5.159)]} and Lt = 90.3{1- exp[-0.173(t + 2.215)]}, respectively, where L = eye-to-fork length in cm and t = age in years. The length-weight (W, kg) relation for both sexes was logeW = 2.77 logeL - 10.14. The sex ratio was 0.89 male to 1 female; few females had ovaries in advanced stages of maturation. The mean coefficient of condition (K = 105W/L) for all fish was 1.50. Annual total mortality was estimated to be 18% from catch-curve analysis and the annual rate of exploitation was at least 7%. During summer, paddlefish were most often found in areas downstream from submerged sandbars where the current velocity was 0-0.3 m/s and the depth was 2-3 m; fish were located in areas where the depth was at least 3 m during winter. Paddlefish moved extensively; many tagged fish moved farther than 50 km, and some traveled over 600 km within 1 yr. Paddlefish should be manged consistently within biologically relevant regions.