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? Do fall HFEs result in increased upstream migration by brown trout to find suitable spawning habitat? "Within the rest of the October-November time frame, one should look for the heavy rains and rising stream flows, which trigger fresh migrations of brown trout from lake to stream and river to feeder creek." 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 Hasegawa, K. 2016. The density dependent interspecific competition between nonnative salmonids, rainbow trout and brown trout. Environmental Biology of Fishes. April 2016, Volume 99, Issue 4, pp 433-438. Hasegawa, K., N. Ishiyama, H. Kawai. 2014. Replacement of nonnative rainbow trout by nonnative brown trout in the Chitose River system, Hokkaido, northern Japan. Aquatic Invasions. Vol. 9 Issue 2, p221-226. 6p. Brown trout tend to grow faster and be more aggressive than rainbow and brook trout, so they outcompete the rainbows and the brooks for limited resources. When they get big enough, brown trout are known to prey directly on smaller trout... [2] S.D. George, B.P. Baldigo, A.J. Smith, and G.R. Robinson. 2016. Effects of extreme floods on trout populations and fish communities in a Catskill Mountain river. Freshwater Biology. "The divergent responses of brown trout and rainbow trout populations to the summer flood could be explained by competitive interactions. Brown trout are autumn spawners, whereas rainbow trout are spring spawners, and thus, YOY brown trout emerge earlier, are larger and may outcompete YOY rainbow trout (Gatz, Sale & Loar, 1987; Strange et al., 1992 ). Conversely , the autumn spawning of brown trout increases the risk of egg loss if autumn or winter floods occur. Several investigations showed that YOY brown trout or brook trout were generally more numerous than YOY rainbow trout except during years when floods scoured the eggs of the autumn spawners (Seegrist & Gard, 1972; Strange et al., 1992; Warren et al., 2009 ). " [3] Spearfish Creek offers some of the best fishing in the Black Hills. Well known for its ample brown, rainbow and even brook trout, the stream, with its clear, cool waters is the destination of many anglers year-round. But with 2,000 to 4,000 fish per mile, the size of the fish may not be as large as in other area creeks. So, the South Dakota Game, Fish and Parks removed approximately 3,000 brown trout this summer in hopes of enhancing the size of the fish... Davis said the rainbow trout population is also ample, but sizes also are smaller than in other streams. He said he hopes removing some of the brown trout will give the rainbows a boost in size as well. Davis said brown trout are generally more aggressive and will outcompete a rainbow population. [4]