Laserfiche WebLink
<br />-9- <br /> <br />Trout population density (fables 2, 4, and 6) and biomass (fables 3, 5, and 7) estimates provide <br />" convincing evidence that the chronic low streamflow conditions (in effect since March 1990) have <br />been detrimental to the trout population. Moreover, the continued decline in density and biomass <br />from October 1990 to October 1991 indicate continued low flows are holding back recovery. With <br />rare exception, the species and total trout density estimates for October 1990, April 1991, and <br />October 1991 are below the lower 95% confidence Iimit(s) for the same statistics for September 1989. <br />The only exceptions were brown trout at the IFIM site for October 1990, April 1991, and cutthroat <br />trout at the Ferris Canyon site for April 1991 (fable 2). <br /> <br />Table 2. Dolores River trout (:2: 15 cm) density (n/ha), 1986-1991. <br /> <br />Species 10/86 10/87 10/88 09/89 10/90 04/91 ~I <br /> IFIM Site - Metaska Campground - River Mile 0.5 <br />Brown 50 104 57 64(62)" 67 63 24 <br />Rainbow 27 29 36 89(87) 73 50 64 <br />Cutthroat 16 23 13 30(28) 16 5 2 <br />Total trout 91 145 106 183(177) 142 90 84 <br /> Ferris Canyon Campground - River Mile 6 <br />Brown 26 49 101 116(110) 81 44 95 <br />Rainbow 4 4 62 82(63) 55 15 32 <br />Cutthroat 2 8 20 10(9) 2 89 5 <br />Total trout 31 82 138 208(188) 133 93 132 <br /> Rock Stockpile Area - River Mile 10 <br />Brown 18 141 167 99(97) 79 55 74 <br />Rainbow 4 21 52 82(71) 55 34 31 <br />Cutthroat 0 2 99 20(18) 0 57 2 <br />Total trout 21 165 318 201(191) 131 150 105 <br /> <br />"Number in parentheses are the lower 95 % confidence limit. <br />