Natal Origins Project (NO)

There is a low probability for an individual rainbow trout to move large distances. Abundance is a key factor: the more rainbow trout upstream in the Lees Ferry reach = more trout will move downstream to the LCR reach in search of unoccupied habitat Condition may be a secondary factor: when food resources become limited, rainbow trout will move downstream in search of food Recruitment in the reach below the LCR can be accounted for solely by immigrants from upstream sources Food limitation led to the collapse in the trout population, and by extension also likely happened in the downstream reaches. Inflow hydrology and reservoir limnology likely govern the quality and quantity of nutrients supplied to the downstream river segments. Nutrient limitation is hypothesized as being the “BIG HAMMER” to the riverine ecosystem, which needs to be evaluated in greater detail in future research. [1]

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Updates https://www.usbr.gov/uc/progact/amp/twg/2017-01-26-twg-meeting/AR16_Yard.pdf Episodic movement occurs under periods of high recruitment (lots of little trout looking for a place to live) https://www.usbr.gov/uc/progact/amp/twg/2017-01-26-twg-meeting/AR16_Yard.pdf Episodic movement occurs under periods of environmental stress (poor conditions) https://www.usbr.gov/uc/progact/amp/twg/2017-01-26-twg-meeting/AR16_Yard.pdf https://www.usbr.gov/uc/progact/amp/twg/2017-01-26-twg-meeting/AR16_Yard.pdf

Links and Information Bioenergetics Studies The Rainbow Trout Page The Near Shore Ecology (NSE) / Juvenile Chub Monitoring (JCM) Page The Nutrients Page Background Initial investigations found: Efficacy of Mechanical Removal is dependent on immigration levels RBT abundance was high and variable, partially offset by trout immigration BNT were more predaceous than RBT RBT were more numerous than BNT Predation risk is a function of both density & predatory behavior Information Needs: What controls trout abundance? Where were RBT migrants originating from? How many sub-adult HBC move into the mainstem? How variable was subadult HBC survival? Was there a relationship between HBC survival & RBT abundance? Outcomes: Need to develop alternative sampling methods for determining trout and chub abundance and vital rates Natal Origin Project: Movement and trout dynamics NSE/JCM Projects: Juvenile HBC survival and other regulating factors Presentations and Papers 2018 Yackulic, C.B., Korman, J., Yard, M.D., and J. Dzul.. 2018. Inferring species interactions through joint mark-recapture analysis. Ecology. Early view article. 2017 Korman, J., M.D. Yard, and T.A. Kennedy. 2017. Trends in rainbow trout recruitment, abundance, survival, and growth during a boom-and-bust cycle in a tailwater fishery. Trans. Am. Fish. Soc. 146:1043-1057. Korman, J., and M.D. Yard. 2017. Effects of environmental covariates and density on the catchability of fish populations and the interpretation of catch per unit effort trends. Fish. Res. 189:18-34. Dzul, M.C., Yackulic, C.B., and J. Korman. 2017. Estimating disperser abundance using open population models that incorporate data from continuous detection PIT arrays. Can. J. Fish. Aquat. Sci. e-first article. Boom-and-Bust Cycles in the Population of Rainbow Trout in Glen Canyon and Effect of Fall High Flow Experiments Natal Origin Project PPT 2016 Yard, M.D., Korman, J., Walters, C.J., and T.A. Kennedy. 2016. Seasonal and spatial patters of growth of rainbow trout in the Colorado River in Grand Canyon Arizona. Can. J. Fish. Aquat. Sci. 73:125-139. Korman, J, Yard, M.D., and C.B. Yackulic. 2016. Factors controlling the abundance of rainbow trout in the Colorado River in Grand Canyon in a reach utilized by endangered humpback chub. Can. J. Fish. Aquat. Sci. 73:105-124. Dodrill, M.D., Yackulic, C.B., Yard, M.D. and J.W. Hayes. 2016. Prey size and availability limits maximum size of rainbow trout in a large tailwater: insights from a drift-foraging bioenergetics model. Can. J. Fish. Aquat. Sci. 73: 759-772. Dzul, M.C., Yackulic, C.B., Korman, J., Yard, M.D., and J.D. Muehlbauer. 2016. Incorporating temporal heterogeneity in environmental conditions into a somatic growth model. Can. J. Fish. Aquat. Sci. 74:316-326. Finch, C., W. E. Pine, C. B. Yackulic, M. J. Dodrill, M. Yard, B. S. Gerig, L. G. Coggins, and J. Korman. 2016. Assessing Juvenile Native Fish Demographic Responses to a Steady Flow Experiment in a Large Regulated River. River Research and Applications 32:763-775 Natal Origins of Rainbow Trout Project, Years 1-4 (Nov 11 – Dec 15) 2015 Korman et al. 2015. Factors controlling the abundance of rainbow trout in the Colorado River in Grand Canyon in a reach utilized by endangered humpback chub. Canadian Journal of Fisheries and Aquatic Sciences, 2016, 73(1): 105-124 Update on the 2015 decline in fish condition and abundance at Lees Ferry Natal Origins of Rainbow Trout: Glen Canyon and Marble Canyon Rainbow Trout Growth, Condition, Population Dynamics and Modeling in Glen Canyon 2014 Yackulic, C.B, Yard, M.D., Korman, J. and D.R. Haverbeke. 2014. A quantitative life history of endangerd humpback chub that spawn in the Little Colorado River: variation in movement, growth, and survival. Ecol. Evol. 4: 1006-100. New Insights on Trout from the Natal Origins Study Natal Origins of Rainbow Trout: Glen Canyon and Marble Canyon 2013 Natal Origins: Glen Canyon and Marble Canyon Other Stuff Local recruitment in Marble Canyon down to the LCR: There does appear to be some local trout recruitment in Marble Canyon down to the LCR but the numbers of trout at the LCR are driven more by immigration from upstream sources (i.e. the Lees Ferry reach) than by local recruitment. [2] [3]