The Ichthyofauna of Small Streams on the Charles M. Russell National Wildlife Refuge, Montana

Abstract

The ichthyofauna of the small streams on the Charles M. Russell National Wildlife Refuge is poorly known because no systematic survey had been conducted previously. We sampled fish and visually evaluated habitat at 18 third and fourth order streams, stratified to ensure good geographic coverage. A total of 13 streams had fish present, two streams had water but no fish, and three streams had no water present. Most streams with water were intermittent; only two streams had flowing water. A total of 19 fish species was captured of which 14 species were native to Montana. From one to 12 fish species, and from one to 899 individual fish were captured per site. Overall, 87 percent of individual fish captured were native species. Introduced species made up over 50 percent of fish captured at only one site and 7 of 13 streams had no introduced species. The most common species were fathead minnow (Pimephales promelas), plains minnow (Hybognathus placitus), lake chub (Couesius plumbeus), white sucker (Catostomus cornmersoni), common carp (Cyprinus carpio), flathead chub (Platygobio gracilis), and longnose dace (Rhinichthys cataractae). Rough positive correlations between a qualitative habitat index and numbers offi sh species and individual fish were observed. Because most of the species we captured are rare in the adjacent Missouri River or Fort Peck Reservoir, we suspect that most fish complete their life cycles within the streams we sampled, despite the low quantities of water present. We further speculate that connectivity among streams that enter Ft. Peck Reservoir has been reduced because the reservoir acts as a partial barrier to the movements of most of the fish species we captured.