Daily ration, feeding periodicity and prey selection of sauger (Stizostedion canadense) in the Ohio River
Wahl, David H.
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Predation by saugers was evaluated from stomach contents of 550 saugers collected by gillnetting in the Gallipolis Pool of the Ohio River during June 1980 - August 1981. Abundance of prey items in the river was assessed from seine samples collected at similar sites during the same period. Gizzard shad were the most abundant prey in sauger stomachs, comprising 42% of all identified prey, followed by emerald shiners (28%), freshwater drum (16%), channel catfish (12%), and mimic shiners (1%). Close correlation between abundance and size of prey in stomachs and in seine samples suggested lack of selection by saugers. Annual food consumption of saugers averaged 1.1% of the body weight per day. Growth and daily ration were high from August to January (maximum in October) and low from March to July. Rapid growth and high food consumption throughout the fall and early winter relate to the extended period of high temperatures and increased availability of gizzard shad. Conversion efficiency estimates during the growing season averaged 20%, similar to reports for other aquatic systems. Annual conversion efficiency averaged 15.7%, indicating a 27% overestimate of annual efficiency levels through the use of only growing season data. Daily feeding activity was continuous for saugers during October - January when light intensity was low and food abundance and daily ration were high. Feeding was also continuous during March - May but was highly variable. Feeding was significantly greater during the daylight hours in June, but was reduced during daylight hours in August. Turbidity levels were much higher in June than in August and may have affected the patterns of feeding periodicity during these months.
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