Smallmouth Bass Page

The predatory threat of invasive and large-bodied piscivorous taxa such as smallmouth bass in the upper Colorado River basin is substantial. For example, based on results of a bioenergetics model, Johnson et al. (2008) ranked smallmouth bass as the most problematic invasive species because of their high abundance, habitat use that overlaps with most native fishes, and ability to consume a wide variety of life stages of native fishes (Bestgen et al. 2008). Expanded populations of piscivores such as smallmouth bass are a major impediment to conservation actions aimed at recovery efforts for the four endangered fishes in the upper Colorado River basin: Colorado pikeminnow Ptychocheilus lucius, razorback sucker Xyrauchen texanus, humpback chub Gila cypha, and bonytail Gila elegans (U.S. Fish and Wildlife Service 2002a, b, c, d). [1]

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Updates PAGE, Ariz. —On July 1, 2022, juvenile smallmouth bass were found in the Colorado River below the Glen Canyon Dam. Smallmouth bass are a predatory non-native fish that have adversely impacted native and federally protected fish in the upper basin of the Colorado River over the last 20 years. The National Park Service (NPS) is working closely with partners and stakeholders to coordinate rapid response actions to address this finding in accordance with previously approved management plans. Lower lake levels at Lake Powell and rising temperatures in the Colorado River have increased concerns that non-native, warm-water predators, including smallmouth bass, could pass through the dam and begin reproducing. If these warm-water predators establish populations below the dam, it is likely they would negatively impact native fish communities in Glen Canyon National Recreation Area and in Grand Canyon National Park. The NPS encourages anglers to report any observations or catches of smallmouth bass below the dam. If caught, please remove the fish, put on ice and contact staff at Glen Canyon National Recreation Area or Grand Canyon National Park with a description of the location where found. Report findings to: Jeff Arnold, Glen Canyon National Recreation Area, e-mail us or Brian Healy, Grand Canyon National Park, e-mail us. [2]

Links Nonnative Invasive Aquatic Species Projects Evaluate effects of flow spikes to disrupt reproduction of smallmouth bass in the Green River downstream of Flaming Gorge Dam Presentations and Papers 2022 'Worst fears confirmed' in biologists' fight to save ancient Colorado River fish Flow spike to reduce smallmouth bass reproductive success, Green River, 2021 Near-Term Threat of Smallmouth Bass Establishment below Glen Canyon Dam Fish modelling to support management decisions Other Stuff