WSP05499

• File Number: 8200.766
• Description: Gunnison River General
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 4/1/1997
• Author: Mueller and Hiebert
• Title: Assessment of Kokanee Salmon Transport through Blue Mesa Powerplant - Colorado - During the Spring and Summer of 1994-1996
• Water Supply Pro - Doc Type: Report/Study

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Table 5.
based on
of 1994.

Estimates of
hydroacoustic

the pelagic fishery of Blue Mesa Reservoir
surveys conducted in June, AuguSt, and October

Month Fishjha STD Population Range (90% eonf. )
1994
June 485 983,600 ----------------
August 344
330
Average 337 7.63 683,400 586,100 to 780,800
October 149
110
Average 130 19.5 263,600 14,200 to 513,100
1995
August 201 454,000 -----------------

Population estimates were also calculated based on specific fish
density information and weighted area of the major basins and
tributary arms of the reservoir. These estimates were conducted to
determine if distribution might skew reservoir-wide estimates.
Distribution did not. Population estimates were similar for both
techniques (Tables 5 and 6) and a second set of confidence limits were
not calculated.

Table 6. Pelagic fish population estimates based on weighted area and
fish densities for reservoir basins and tributaries during 1994 and
1995.

1994 Tributaries Io1a Cebolla Sapinero Total
June 47,900 99,750 496,070 317,280 961,000
August 124,180 230,110 176,810 135,450 666,550
October 98,350 65,210 64,380 50,200 278,140
1995
August 81,400 103,120 120,880 146,860 452,260

Fish Size Size analysis of detected fish showed some interesting
but inconclusive trends. Target strength of returned signals were
analyzed and separated into three target strengths; >-38dB, -39 to -
44dB, and <-45 or basically, large, medium, and small sized fish.
Figure 18 shows the proportion of these three size groups of fish.
Over 80 percent of the June sample was made up of fish smaller than

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