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c) C, ...... (0 C) o SAN JUAN RIVER TOTAL HABITAT COUNTS 125 W ::l ::5100 - :!!:. ~ 75 - z ::l o CJ 50 !;( I- m 25 <( J: o o 50 100 125 150 RIVER MILE 200 250 225 25 75 175 1- LOW FLOW - MEDIUM FLOW - HIGH FLOW I Figure 3.12. Total count of habitats by river mile for the San Juan River averaged for all low-, medium-, and high-flow mapping runs conducted by Bliesner and Lamarra (2000). Habitat count was determined as the total number of different habitats (versus different habitat types) within each mile reach of river. Portions of the San Juan River with high habitat counts and richness were the most used by adult and juvenile Colorado pikeminnow, and by stocked razorback sucker. Although, on average, habitat richness was not vel)' high in the river, as shown in Table 3.3, the San Juan River provided areas with high richness that were not only found, but heavily used, by the endangered fishes. Only the lower 70 miles of the river appear to be low in habitat richness, and that is likely a constraint of geological features. Propst and Hobbes (2000) and Gido and Propst (1999) showed that secondary channels were an important habitat for fishes in the San Juan River. Secondary channels are not as common in other Colorado River streams as in the San Juan River, and it was thought that secondary channels may provide the same type of habitat that backwaters and low-velocity main channel habitats provide in other rivers. Initially, it was anticipated that YOY Colorado pikeminnow used these areas in late summer and fall, but low numbers of wild Colorado pikeminnow prevented verification. When YOY Colorado pikeminnow were stocked into the San Juan River, substantial numbers of YOY September 2000 3-28 Program Evaluation Report