Salmonid Abundance and Distribution in the middle Green River

Salmonid abundance and distribution in the Green River between Flaming Gorge Dam the Split Mountain Boat Ramp (middle Green River, Figure 1) are governed by recruitment, habitat requirements and interspecific competition, played out on the framework of the Green river hydrology and geomorphology. Although salmonids historically did not inhabit the middle Green River after the end of the last glaciation, construction of the Flaming Gorge Dam in 1962 drastically reduced water temperature and silt in the middle Green River, creating habitat that meets salmonid needs for cool, clear water. The tail water and downstream section of the Green support four types of salmonids: brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), Snake River cutthroat trout (Oncorhynchus clarki bouvieri), and mountain whitefish (Prosopium williamsoni). While the brown trout and the whitefish are self- sustaining populations, the rainbow and cutthroat trout are maintained through a large stocking effort (Schneidervin 2006, personal communication). Salmonid abundance patterns result from both food availability and the influx of new trout every year through natural reproduction and stocking. With the exception of P. williamsoni, the salmonids are closely related and have very similar habitat requirements. On a broad scale, temperature and foo