What is the liklyhood they could have left the creek down stream to the river where more water exists?
I am not a biologist but...
Like earlier posts mentioned,
it depends.
A study of resident trout on a popular local freestone river with very little supporting data returns speculated "
some downstream movement to better adult habitat might occur as trout grow". There was no mention of a low water condition.
Fish will search for favorable temperature and dissolved oxygen that are affected by local conditions, e.g., riparian barrier and density (shade), topography-geology (
gradient, shade, springs, substrate, isolation...), time of day, weather...
Some studies suggest these local conditions may actually cause fish to move
upstream to find favorable conditions.
Life history (
fluvial, adfluvial, resident) of those particular fish in that particular stream in relationship to other bodies of water can also be a factor.
What
@Stonedfish and
@Mossback said. Despite the Latin names, it really is a simple description of the relationship between adult life strategies/behavior and spawning strategy.
Fluvial - Adults live in larger rivers and spawn in smaller tributaries (think Yellowstone Cutthroat trout in Paradise Valley - they live in the Yellowstone but spawn in tribs like Mill Creek, Pine Creek, Big Creek, Gardner River)
Adfluvial (often termed lacustrine) - Adults live in lakes and migrate to spawn in tributaries (think YCT in Yellowstone Lake - they live in the lake but spawn in...
Are you going to just stay where you are, or would you move to a place that fixes all of those things?
The Travers fish may just kick everyone else out of the nearest prime lie if it has everything required and eat little guys for trespassing.