Life history of paddlefish Polyodon 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/second, 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 one year. Paddlefish should be managed consistently within biologically relevant regions.
Food habits and food selectivity of the black bullhead (Ictalurus melas) in Lake Poinsett, South Dakota, were studied from March to November 1970. The black bullhead preyed upon a wide range of food sources in the limnetic, littoral, and benthic zones and seasonal differences in diet occurred in response to availability of prey species. The total food volume in stomachs of 558 black bullheads (143–304 mm total length) comprised about 32% planktonic crustaceans, 25% chironomids, 27% fish, 9% crayfish, 2% filamentous algae, and 5% miscellaneous organisms. Planktonic crustaceans made up 94.4% and chironomids made up 5.6% of the volume of food ingested by 220 young-of-the-year black bullheads. Black bullheads were most selective for the largest cladocerans available, Leptodora kindtii, Daphnia pulex, and D. galeata mendotae, and for Chironomus spp. pupae. Black bullheads were least selective for Diaphanosoma leuchtenbergianum, copepods, and chironomid larvae. The black bullhead in Lake Poinsett was primarily a selective planktivore throughout its life history.
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