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.
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 is more associated with immigration from upstream sources (i.e. the Lees Ferry reach). [5][6]
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