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Limiting factor

     Is water temperature a limiting factor for trout habitat health in the Dolores River basin?

     Water temperature determines the suitability of a habitat through its role in physiological processes that affect growth, behavior, reproduction, and survival throughout all life stages [1, 2]. Modeling how trout distribution may develop in response to climate change in the western United States has shown that stream temperature, together with flow regime, and biotic interactions, likely will drive shifts in fish species distribution [3]. Therefore, water temperature is important to monitor, especially given a changing climate [2, 4, 5].

    Limiting | Drought | Debris

Installing temperature sensor at Slate

Slate 1

     Water temperature affects physiological processes in fish that determine growth, food consumption, metabolism, reproduction, and survival [1, 6, 7], and which also influence behavior and habitat selection [1, 2, 8]. Some physiological or biochemical processes, including growth, food consumption, and activity have optimum temperatures. For example, the rate of growth may increase with rising water temperature to a point and then decline [9]. In fact, studies have shown that growth rate is the most sensitive physiological process to water temperature [1, 10].

     Water temperatures that are too high, or too low, can lead to death, either immediate or delayed [9, 11]. The temperature extremes that result in death are influenced by the developmental stage of the fish and the temperature range to which it is accustomed [9]. Fish tend to select an environment near their optimal growth temperature, and generally have an optimal range of temperatures [9] or “zone of efficient operation” [12].

     Through its effect on growth, temperature plays a key role in determining the age when fish become sexually mature. Variation in the fecundity (number of eggs) of female salmonids is strongly related to their length [11, 13]. Water temperature also has a strong effect on recruitment of individuals from one-year class to the next in high-elevation populations [2, 14, 15, 16].

     Water temperature’s effects on growth, reproduction, and survival lead to consequences in fish behavior, in general, and to differences in habitat selection among salmonid species and subspecies [11]. Temperature can drive daily movements, seasonal movements, and competitive interactions [2, 17]. Therefore, water temperature is useful as an indicator of habitat suitability. Mean summer water temperature, together with available stream length, can be used to identify potentially suitable habitat for cutthroat trout [2, 13, 14].

     Researchers studying cutthroat, brook, rainbow, and brown trout found that stream temperature, flood seasonality, and the presence of other species strongly affected habitat occupancy. The coldest streams were occupied by cutthroat trout and brook; rainbow trout inhabited warmer streams; and brown trout, in the warmest streams [3].

     The influence that water temperature has on local and basin-scale habitat selection, species distribution, health, and movements make it a useful parameter for assessing and monitoring trout habitat and populations. Identifying thermal criteria for species is critical to the ability to maintain or restore both native and sport trout fisheries [11]. Not only is water temperature a key driver of the distribution, abundance, and health of a population, but it is also a sensitive indicator, because even small changes can have substantial effects [4, 5, 17].


  1. J. E. Williams, M. P. Dombeck, and C. A. Wood, “My Healthy Stream, A Handbook for Streamside Owners,” Trout Unlimited, Arlington, VA, 2012.

  2. G. Fornshell and C. Myrick, “Early Rearing of Cutthroat Trout Technical Report, “Western Regional Aquaculture Center, Seattle, 2009.

  3. J. J. Roberts, K. D. Fausch, D. P. Peterson and M. B. Hooten, “Fragmentation and Thermal Risks from Climate Change Interact to Affect Persistence of Native Trout in the Colorado River Basin,” Global Change Biology, pp. 1-16, 2013.

  4. Todd, A. S., M. A. Coleman, A. M. Konowal, M. K. May, S. Johnson, N. K. M. Vieira and J. F. Saunders, “Development of New Water Temperature Criteria to Protect Colorado’s Fisheries,” Fisheries, vol. 33, no. 9, pp. 433-443, 2008.

  5. Quality Criteria for Water, U.S. Environmental Protection Agency, 1986

  6. M. K. Young, “Colorado River Cutthroat Trout: a Technical Conservation Assessment,” U.S.D.A. Forest Service, Rocky Mountain Station, Fort Collins, 2008.

  7. S. J. Wenger, D. J. Isaak, C. H. Luce, H. M. Neville, K. D. Fausch, J. B. Dunham, D. C. Dauwalter, M. K. Young, M. M. Elsner, B. E. Rieman, A. F. Hamlet and J. E. Williams, “Flow Regime, Temperature, and Biotic Interactions Drive Differential Declines of Trout Species under Climate Change,” PNAS, vol 108, no. 34, pp. 14175-14180, 2011.

  8. K. D. Fausch, S. Nakano and K. Ishigaki, “Distribution of Two Congeneric Chars in Stream of Hokkaido Island, Japan: Considering Multiple Factors across Scales,” Oecologia, Vol 100, p 1-12, 1994.

  9. T. W. Hillman, M. D. Miller and B. A. Nishitani, “Evaluation of Seasonal-Cold-Water Temperature Criteria,” Idaho Division of Environmental Quality, Boise, 1999.

  10. D. W. Welch, Y. Ishida and K. Nagasawa, “Thermal Limits and Ocean Migrations of Sockeye Salmon (Oncorhynchus nerka): Long-Term Consequences of Global Warming,” Canadian Journal of Fisheries and Aquatic Sciences, vol. 55, pp. 937-948, 1998.

  11. C. C. Coutant, “Thermal Preference: When Does an Asset Become a Liability?” Environmental Biology of Fishes, vol. 18, pp. 161-172, 1987.

  12. M. Jobling, Fish Bioenergetics, New York, NY: Chapman and Hall, 1994.

  13. W. A. Brungs and B. R. Jones, “Temperature Criteria for Freshwater Fish: Protocol and Procedures,” U.S. Environmental Protection Agency, Duluth, MN, 1977.

  14. E. B. Bear, T. E. McMahon and A. V. Zall, “Comparative Thermal Requirements of Westslope Cutthroat and Rainbow Trout: Implications for Species Interactions and Development of Thermal Protection Standards,” Transactions of the American Fisheries Society, no. 136, pp. 1113-1121, 2007.

  15. L. I. Cranshaw, “Physiological and Behavioral Reactions of Fishes to Temperature Change, Journal of the Fishery Research Board of Canada, vol. 34, pp. 730-734, 1977.

  16. C. C. Downs, R. G. White and B. B. Shepard, “Age at Sexual Maturity, Sex Ratio, Fecundity, and Longevity of Isolated Headwater Populations of Westslope Cutthroat Trout,” North American Journal of Fisheries Management, vol. 17, pp, 85-92, 1997.

  17. P. Tyler and P. Calow, Fish Energetics: New Perspectives, London: Croom Helm, 1985.

    Limiting | Drought | Debris 

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