Rainbow Trout

Rainbow trout in the hands of an angler

 

Rainbow trout (Oncorhynchus mykiss) are native to North America in waters that drain to the Pacific Ocean from northern Mexico to Alaska. Of the nonnative fish in Yellowstone, rainbow trout have the closest geographic origin. As the most adaptable members of the salmonid family, they have been successfully introduced throughout the world. Unfortunately they readily hybridize with cutthroat trout.

 

Description

• Silvery body, red lateral band, often white on the edge of lateral fins.
• Numerous black spots on head and back, none on belly.

Behavior

• Mainly spring spawners between March-July. Select populations spawn in fall.
• Eats aquatic and terrestrial insects, crustaceans, mollusks and earthworms.

Distribution

• Widely distributed due to historic stocking efforts.
• Not present in Yellowstone Lake.
• Not present in the Yellowstone River above the Upper Falls or the Snake River.

 

Cutthroat x Rainbow Trout Hybrids

In waters where rainbow trout have been introduced, there has been a serious degradation of the cutthroat trout population through interbreeding.

Presently, hybridized cutthroat trout exist throughout the Bechler, Falls, Gallatin, Gardner, and Lamar river drainages, and the Yellowstone River below the Upper Falls. Hybrids will have characteristics consistent with both species, often making identification difficult.

 

Cutthroat x rainbow trout hybrid

NPS

 

Resources

Bigelow, P.E. 2009. Predicting areas of lake trout spawning habitat within Yellowstone Lake, Wyoming. Doctoral dissertation, University of Wyoming, Laramie, WY.

Gresswell, R.E. 2009. Scientific review panel evaluation of the National Park Service lake trout suppression program in Yellowstone Lake, August 25–29, 2008: Final report, October 2009, Edited by USGS Northern Rocky Mountain Science Center. Bozeman, MT.

Koel, T.M., P.E. Bigelow, P.D. Doepke, B.D. Ertel, and D.L. Mahony. 2005. Nonnative lake trout result in Yellowstone cutthroat trout decline and impacts to bears and anglers. Fisheries 30(11):10–19.

Koel, T.M., P.E. Bigelow, P.D. Doepke, B.D. Ertel, and D.L. Mahony. 2006. Conserving Yellowstone cutthroat trout for the future of the Greater Yellowstone Ecosystem: Yellowstone’s Aquatic Sciences Program. Yellowstone Science 14(2).

Middleton, A.D., T.A. Morrison, J.K. Fortin, M.J. Kauffman, C.T. Robbins, K.M. Proffitt, P.J. White, D.E. McWhirter, T.M. Koel, D. Brimeyer, and W.S. Fairbanks. 2013. Grizzly bears link non-native trout to migratory elk in Yellowstone. Proceedings of the Royal Society B 280:20130870.

Munro, A.R., T.E. McMahon, and J.R. Ruzycki. 2006. Where did they come from?: Natural chemical markers identify source and date of lake trout introduction in Yellowstone Lake. Yellowstone Science 14(2).

Wyoming Water Project. 2014. Science supporting management of Yellowstone Lake fisheries: Responses to frequently asked questions. Trout Unlimited: Lander, WY.

Ruzycki, J.R., D.A. Beauchamp, and D.L. Yule. 2003. Effects of introduced lake trout on native cutthroat trout in Yellowstone Lake. Ecological Applications 13:23–37.