Effects of non-native salmonids on stream ecosystems

non-native brook troutFabio Lepori and Kurt Fausch
Stream Fish Ecology Laboratory, Colorado State University, Fort Collins, CO

Joe Benjamin and Colden Baxter
Stream Ecology Center, Idaho State University, Pocatello, ID

Across Western U.S. streams, populations of non-native brook trout (above) are replacing native cutthroat trout (below); what are the consequences for the food web? One hypothesis tested is that non-native trout alter key energetic pathways, such as the flux of aquatic invertebrates into the riparian area, with consequences affecting not only stream biota, but also reverberating to neighboring riparian communities. Hypotheses are tested using a blend of approaches, ranging from field experiments to large scale observational studies.native cutthroat trout



Funding for this research is provided by the National Science Foundation.

A Field Test of Effects of Livestock Grazing Regimes on Invertebrate Food Webs that Support Trout in Central Rocky Mountain Streams

W. Carl Saunders
Department of Fish, Wildlife and Conservation Biology
Colorado State University

Although current grazing management, as it relates to streams, is designed to protect bank stability and instream habitat, recent research indicates that riparian vegetation itself may also supply terrestrial invertebrates to the stream system that are critical for sustaining trout. General guidelines used to manage riparian grazing include maintaining 40% to 50% of the aboveground vegetation to protect plant roots that bind banks, and maintaining at least a four inch stubble height to prevent browsing on riparian shrubs. The guiding principle has been that bank erosion causes siltation that fills in pools that trout need for overwinter survival, and clogs riffles that support aquatic invertebrates that make up much of trout diets. However, research in Japan, New Zealand, Alaska, and Virginia, as well as my M.S. research, is changing the basic assumptions about what is needed to sustain trout populations.


Effects of groundwater withdrawal and drought on native fishes in Great Plains streams

Jeffrey A. Falke
Department of Fish, Wildlife and Conservation Biology
Colorado State University
Goals and Objectives:  Intensive groundwater withdrawal for irrigation over the past century has resulted in significant declines in groundwater levels across the Great Plains, and in rivers with high groundwater connectivity, to decreased annual discharge. Lowered flows have led to decreased dispersal opportunities among the spawning, rearing, and refuge habitats vital for the persistence ofnative fish populations. My research focuses on:
  • Linking fish ecology to groundwater hydrology in a western Great Plains stream to make recommendations for conservation and management under climate change and drought.
  • Measuring the spawning phenology and recruitment of under-studied Great Plains fishes across spatial scales.