That helps assure a good mix of genetics and a robust fish population. Finding spawning habitat may not be the only need to move about. In small streams, fish find refuge in deep pools to ride out the winter. Getting to the same pools may mean the difference of surviving a summer when flows drop and temperatures climb. Without the access to these necessary habitats, fish populations may suffer.
Mobility is everything.
The Service's Arizona Fishery Resources Office is similarly engaged. The East Fork White River is important habitat for two fishes, both federally listed as threatened, the loach minnow and Apache trout, an important sport fish. But a low-head dam that delivered irrigation water also blocked fish movement. The White Mountain Apache Tribe and Arizona Fishery Resources Office redesigned the dam to continue delivering irrigation water. Flows are now concentrated midstream over a natural bottom that easily passes fish.