Juvenile Pallid Sturgeon are Piscivorous: A Call for Conserving Native Cyprinids

Abstract

We examined the diets of age-6 and age-7 hatchery-reared juvenile pallid sturgeon Scaphirhynchus albus (mean fork length [FL] = 538 ± 13 mm [90% confidence interval]; mean weight = 518 ± 49 g) and indigenous shovelnose sturgeon S. platorynchus (mean FL = 525 ± 12 mm; mean weight = 683 ± 41 g) sampled in 2003 and 2004 from the Missouri River above Fort Peck Reservoir, Montana. Diet overlap between juvenile pallid sturgeon and shovelnose sturgeon was low. Fish were the primary prey of juvenile pallid sturgeon, and aquatic insects were the primary prey of shovelnose sturgeon. Sturgeon chub Macrhybopsis gelida and sicklefin chub M. meeki, two species that have declined throughout much of the Missouri River, comprised 79% of the number of identifiable fish in juvenile pallid sturgeon stomachs. The prevalence of sicklefin chub and sturgeon chub as a food resource of juvenile pallid sturgeon indicates that recovery and management of native cyprinids is a potentially important step in the recovery of pallid sturgeon.