Susceptibility of Rio Grande Cutthroat Trout to Displacement by Non-Native Brown Trout and Implications for Future Management

The Rio Grande cutthroat trout is New Mexico’s state fish; but habitat loss and non-native trout invasions threaten the persistence of this fish throughout the remaining 12% of its historic range. Stakeholders, including state agencies, federal agencies, Tribal nations, Pueblos, and private groups are particularly concerned about the impact that non-native brown trout have on native cutthroat trout.

 

This project will be the first to demonstrate how non-native brown trout negatively affect Rio Grande cutthroat trout populations. The project has two primary objectives: 1) compare the health and characteristics of native Rio Grande Cutthroat Trout in areas both with and without invasive brown trout in cold and warm streams; and 2) determine if competition with invasive brown trout for food resources is associated with reductions in Rio Grande cutthroat trout populations. Understanding the relationship between temperature and non-native species invasion for this southernmost subspecies of cutthroat trout will benefit all cutthroat subspecies into the future as northern latitudes endure the effects of both a warming climate and continued non-native trout invasions.

 

Although the Rio Grande cutthroat trout is not at immediate risk of extinction according to the U.S. Fish and Wildlife Service, more than half of the remaining populations are considered to be in fair or poor condition. Results from this project will be valuable and useful for managers tasked with balancing Rio Grande cutthroat trout restoration efforts while maintaining popular sportfish destinations. This science, for example, could help stakeholders identify and focus restoration efforts on streams with the greatest potential to support Rio Grande cutthroat trout into the future.