Factors associated with Paddlefish restoration success in Oklahoma reservoirs: Availability of potentially suitable spawning substrate in reservoir tributaries

Abstract

American Paddlefish (Polyodon spathula) were once widely distributed, but have been extirpated from parts of their native range, primarily due to habitat fragmentation and degradation brought on by dams. To mitigate losses in Oklahoma, restoration stocking has occurred in some reservoirs with variable success. One factor thought to contribute to successful restoration efforts is the availability of suitable hard substrates in reservoir tributaries used by Paddlefish for the attachment and incubation of their eggs. Using side-scan sonar and supervised classification of aerial imagery we classified 4,550 ha of river substrates upstream of the river-reservoir interface in 10 reservoir tributaries. Additionally, substrate composition and accuracy of substrate maps varied among rivers and was usually associated with river morphology. We found that in general substrate availability coincided with a reservoir's Paddlefish population status. Future research should focus on additional areas identified for substrate mapping as well as studies assessing the location of successful spawning efforts in systems with natural reproduction to further our understanding of suitable habitats.