Nonnative Invasive Aquatic Species

Nonnative Invasive Aquatic Species Non-native fish species present in Grand Canyon were mostly established as a result of intentional stocking to develop sport fisheries in the Colorado River and its tributaries during the late 1800s and early 1900s. Impacts of these actions was not fully understood until later in the 20th Century when a shift to native species conservation management occurred in the NPS. Negative impacts of non-native fish and altered habitats on native fish species has been well-documented throughout the world. Over 20 non-native fish species have been documented in GCNP; However, the more common, large-bodied, species of management concern include rainbow and brown trout, common carp, channel catfish, and bullhead species, striped and smallmouth bass. These species are known predators on native fish or native fish eggs or compete with native fish species. (NPS CFMP-EA_Pg 62) (17 warmwater species, 2 coldwater species, and 1 coolwater species)--- At least 7 additional species occur in nearby or adjoining waters with potential access to the Glen Canyon Ecosystem. LTEMP Experimental Action: Aquatic Resource-Related Experimental Treatments (BA, pages 30-41) [1] Nonnative fish control actions would be implemented if the Little Colorado River humpback chub population declined and proactive conservation actions failed to reverse declining populations [2]. Mechanical removal of nonnative species is a controversial issue in the Colorado River through Glen and Grand Canyons. A spring 2015 meeting of Grand Canyon biologists (NPS, FWS, AGFD, GCMRC) to assess current trout removal triggers resulted in a concept of early conservation measure intervention to maximize conservation benefit to humpback chub and minimize the likelihood of mechanical predator removal. Under the preferred alternative, mechanical removal of nonnative rainbow and brown trout (and other nonnative predators) would be implemented through a triggered, tiered approach (see Appendix D in BA) near the confluence of the Little Colorado River and the Colorado River if conservation actions designed to reverse declines in the Little Colorado River humpback chub aggregation were ineffective. Two different tiers of population metrics would be used to trigger responses such as actions to increase growth and survival of humpback chub (Conservation Actions, Tier 1), or mechanical nonnative fish control (Tier 2), which would only be implemented when Tier 1 conservation actions (actions would focus on increasing growth, survival and distribution of chub in the Little Colorado River and LCR mainstem aggregation area) fail to slow or reverse the decline in the humpback chub population (see Appendix D in BA, Young et al. 2015). In addition, if humpback chub decline and the identified actions are not working, the FWS, in coordination with action agencies and traditionally associated Tribes, will identify future appropriate actions (among other caveats specified in Young et al. 2015).

Online training	Fish Species of the Colorado River in Lower Glen Canyon and Grand Canyon	Fish photos, information, and maps

Updates Potential Threats: "Prior to Glen Canyon Dam, the Colorado River was dominated by highly predacious non-native channel catfish. Catfish are warm water fish...Regular flooding of the LCR may be keeping catfish out of the LCR and cold water in the Colrado River does not provide habitat for catfish or other warm water fish. Without Glen Canyon Dam chubs may have been extirpated from Grand Canyon, catfish would still be the dominant fish in the Colorado River and the LCR." (090711_Minority Report to TWG_FFF_Mark Steffen) Smallmouth Bass -- In early 2000, smallmouth bass increased dramatically in abundance in the Yampa River and Upper Colorado River. Just over a decade later, the species cannot be brought under control.

Links and Information 2016 Fish Protocol Evaluation Panel (PEP) National Park Service Comprehensive Fisheries Management Plan State of Arizona Lees Ferry Fish Management Plan Lees Ferry Anglers Trout Fishery Recommendations Fish Pages Brown Trout Page Green Sunfish Page Presentations and Papers 2017 Is Rainbow Trout Control Necessary, and if so, What is the Most cost-effective approach? PPT System Wide Monitoring PPT 2016 2015 GCMRC Science Updates - Fisheries Native and Nonnative Interactions; Factors Influencing Predation and Competition Quagga Mussel Risk Assessment 2014 Status of Fish Resources Quagga Mussels-Impacts and Solutions for Hydropower Facilities National Park Service Comprehensive Fisheries Management Plan Non-native Fish Control in Tributaries: Grand Canyon National Park (Healy) 2009 Surveys of fish in the Glen Canyon Dam forebay 1992 Nonnative fishes of the Grand Canyon; A review with regards to their effects on native fishes. Allen Haden, GCES Other Stuff NPS Fish Species found in the Grand Canyon NPS Grand Canyon Vertebrate Species List NPS Grand Canyon Threatened & Endangered Species List