Brown Trout

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Brown trout caught at the LCR during the 2013 summer Natal Origins trip

Brown Trout Brown trout are native to Europe and were introduce to tributaries in the Grand Canyon in the 1920s. They are capable of withstanding slightly higher temperature than other trout. Unlike most other trout species, brown trout spawn in the late fall. Their spawning behavior, however, is similar to other trout species. Like rainbow trout, young brown trout feed on aquatic and terrestrial insects and invertebrates but brown trout are more apt to switch to eating other fish as they get bigger. The rainbow trout found in Grand Canyon are more likely to continue to eat mostly insects and invertebrates even as adults. Many studies have shown that rainbow trout and native fish like humpback chub often have a difficult time persisting with large populations of brown trout.[1] Desired Future Condition for the Lees Ferry Trout Fishery A high quality trout fishery in GCNRA, as further described in the Recreation DFC that does not adversely affect the native aquatic community in GCNP. • Minimize emigration of non-native fish from the Lees Ferry reach in Glen Canyon National Recreation Area to downstream locations. • Minimize emigration of non-native warm water fish to the mainstem Colorado River.

Rainbow Trout	Brown Trout

Updates Brown trout numbers during AZGFD monitoring in the Lees Ferry reach. AZGFD identifies that the increase in brown trout numbers may be related to the recent fall HFEs increasing the availability of quality spawning substrate prior to the fall brown trout spawning season. Brown trout are much more likely to eat other fish (piscivory) but since there are many more rainbow trout in the Colorado River between Glen and Marble Canyons, rainbow trout probably eat more fish numerically than brown trout. An increasing brown trout population could, however, pose a problem for both the rainbow trout fishery in Glen Canyon and native fish in Grand Canyon because brown trout eat both rainbow trout and native fish alike. A brown trout collected during 2016 trout monitoring below Flaming Gorge dam that had eaten a 10" stocked rainbow trout.

Information and Links Lees Ferry Rainbow Trout Fishery Page The HFE Page The Temperature Page Bright Angel Creek Trout Reduction Project Questions Why are brown trout increasing in the Lees Ferry reach? When do brown trout spawn in Lees Ferry? Could delaying a fall HFE be effective in disrupting the brown trout spawn? Presentations and Papers 2016 Brown Trout Update Lees Ferry Bright Angel Creek Non-Native Trout Reduction, Grand Canyon National Park 2013 Diets of trout in Bright Angel Creek Nonnative fish control in GCNP tributaries 2011 Yard et al. 2011. Trout piscivory in the Colorado River, Grand Canyon: Effects of turbidity, temperature, and fish prey availability. Transactions of the American Fisheries Society. Other Stuff