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-15- Table 8. Average density (njha) and biomass (kgjha) for river segments 1-6 versus river segments 7-12 for the Dolores River between Metaska Campground and Bradfield Bridge, May & August 1991. Numbers/Hectare Kilograms/Hectare Species & Size (cm) 1 6 7 12 signa 1 6 7- 12 signa - - - May 1991 Browns <!: 15 26.0 25.8 nsd 12.9 8.16 nsd Browns <!: 40 12.2 3.0 ** 9.95 2.14 ** Rainbows <!: 15 33.7 5.2 nsd 20.7 1.60 nsd Rainbows <!: 40 21. 8 0.8 nsd 17.1 0.74 nsd Cutthroat <!: 15 4.5 4.0 nsd 1.62 0.68 nsd Cutthroat <!: 40 2.3 0.4 2.15 0.24 ** Total trout <!: 15 99.0 48.2 nsd 35.9 10.3 * Total trout <!: 40 35.5 3.4 * 29.2 5.5 ** August 1991 Browns <!: 15 81.8 45.8 nsd 15.0 5.0 nsd Browns 20 - 40 33.8 13.3 nsd 6.64 0.92 * Browns <!: 40 8.6 1.3 ** 6.66 2.58 nsd Rainbows <!: 15 51.0 10.8 nsd 15.9 0.77 * Rainbows 20 -40 17.4 2.8 * 6.66 0.38 * Rainbows <!: 40 12.4 0.0 * 9.66 0.00 * Cutthroat <!: 15 22.0 0.67 * 2.24 0.08 * Cutthroat 20 - 40 13.2 0.67 * 0.88 0.08 nsd Cutthroat <!: 40 3.2 0.00 * 1. 36 0.00 nsd asign- level of statistical significance (*) at the psO.05 level for a one- tailed student's t - test; i.e., are the population statistics for river segments 1 - 6 significantly greater than river segments 7-12. The data in Table 8, a summary and statistical analysis of the data presented in Tables lA and 2A (Appendix), provide strong evidence that there is a biological demarcation line in the Dolores River at approximately river mile 6, i.e., just downstream from Ferris Canyon Campground. Downstream from this point all components of the Dolores River trout population are severely depressed. In every instance, the mean density and/or biomass levels for river segments 1-6 are 2-20 times greater than the same statistic for river segments 7 through 12 (Table 8). These statistically significant (in many