A Comparison of Riffle and Beaver Pond-Dwelling Trout in Northeastern Utah

Authors: Susan Washko, Phaedra Budy, Brett Roper, Trisha Atwood

Year: 2018

Abstract

Beavers are increasingly implemented as agents in stream restoration, though little work has shown how fish utilize beaver habitats. While beaver ponds provide many types of refugia to fish, foraging habits, habitat preference, and growth within beaver ponds remains unclear. Trout were expected to forage more within beaver ponds relative to riffles due to hypothesized greater availability of aquatic macroinvertebrates. We also hypothesized that an ample feeding source combined with a lower velocity habitat would result in higher growth for trout that use beaver ponds, and due to this we suspected trout would demonstrate a preference for beaver ponds over riffles. Through a variety of stream surveys and experiments in the Logan River watershed, we determined that there were no differences in growth, body condition, or diet between trout caught in beaver ponds and trout caught in riffles. Brown Trout were larger in beaver ponds, while Bonneville Cutthroat Trout were larger in riffles. Some trout did exhibit fidelity to beaver ponds, though riffles housed more trout per volume of stream. In this system, trout may be highly adapted to beaver-created habitats such that they can utilize both beaver ponds and riffles.