Predation on Age-0 Paddlefish by Walleye and Sauger in a Great Plains Reservoir

Abstract

From July to October 1994 and 1995, the food habits of walleye Stizostedion vitreum, sauger S. canadense, northern pike Esox lucius, and channel catfish Ictalurus punctatus were studied in Lake Sakakawea, a Missouri River main-stem reservoir in North Dakota. In 1994, no paddlefish Polyodon spathula were found in stomachs of these predators. In 1995, 3% of the walleyes, 12% of the saugers, and 1% of the channel catfish with identifiable prey ate wild age-0 paddlefish. Walleyes ate paddlefish from August to October, with the highest proportions in September, whereas saugers ate paddlefish from July to October in equal proportions. Walleye and sauger stomachs contained wild age-0 paddlefish as large as 167 mm body length (BL; 305 mm total length, TL), and one channel catfish stomach contained a 142-mm-BL (269-mm-TL) paddlefish. Predators were also sampled after 8,000 hatchery-reared, age-0 paddlefish (mean BL = 189 mm) were released in White Earth Bay, Lake Sakakawea. Hatchery-reared paddlefish were absent from stomachs of 47 walleyes, 3 saugers, 9 channel catfish, and 3 white bass Morone chrysops with identifiable prey. However, two hatchery-reared paddlefish (175 and 220 mm BL) were found in 2 of 17 northern pike with identifiable prey. Because we found that walleyes and saugers were capable of eating paddlefish of at least 167 mm BL (305 mm TL), many stocked paddlefish may be susceptible to predation. State agencies should consider stocking larger paddlefish where high densities of sauger or large walleyes (>490 mm TL) are present.