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WSP07684
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Last modified
1/26/2010 2:28:26 PM
Creation date
10/12/2006 2:32:01 AM
Metadata
Fields
Template:
Water Supply Protection
File Number
8240.200.10.B
Description
UCRBRIP Annual Report
Basin
Colorado Mainstem
Date
12/22/1997
Author
UCRBRIP
Title
1997 Annual Reports Package Part 3
Water Supply Pro - Doc Type
Publication
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<br />over 12,500 cfs. The high water enabled us to effectively <br />sample many of the flooded tributary mouths that squawfish <br />inhabit during high flows. <br /> <br />A total of 77 adult/juvenile Colorado squawfish were <br />collected in the 4 official reaches, and 11 more in the <br />elective reach. An additional 14 squawfish were observed <br />but not collected in the 4 official reaches, and 3 were <br />missed in the elective reach. Twelve juveniles were too <br />small to pittag, at less than 175mm TL. All others received <br />pittags. The fish ranged from 60 to 786mm, with the average <br />size increasing upstream (Table 1) . <br /> <br />Several distinct year classes appear from a length- <br />frequency graph (not shown). The 1996 ISMP results showed a <br />year class of fish grouped from 200-300mm which are now at <br />300-360mm. The large 1986-87 class, seen in several <br />preceding years data, is still grouped from 500 to 650mm, <br />having not grown as much. <br /> <br />Seventeen squawfish were recaptured, between 1 and 5 years <br />apart. The average growth rate for fish caught in the <br />Colorado River was 20.3mm/year, and 29.7mm/year for the <br />Green, with a range of 7.2 to 48.9mm/year. The average <br />length at first capture was 470.8mm, and the average <br />recapture length was 547.3mm. <br /> <br />The percentage of recaptures has been increasing each year <br />in the Colorado River, but is low and variable in the Green <br />River (Table 2). No fish have been recaptured in an <br />elective reach, but one fish was recaptured in the lower <br />Colorado reach that was originally tagged in the elective <br />reach. <br /> <br />Movement of fish between captures varied from 0 to 109 <br />miles. Fish in the Colorado River are more active than <br />those in the Green river. Average movement in the Colorado <br />was 26.7 miles and only 2.35 in the Green. However, one <br />Colorado River fish was recaptured 5 years later within 0.1 <br />miles of its original capture. One fish originally captured <br />in the Gunnison River (RM 3.0) was recaptured at RM 65.0 in <br />the Colorado River. <br /> <br />Native fishes were more abundant than non-natives, with <br />Colorado squawfish the most abundant of all species except <br />carp in the Green River. Non-native predator fish species <br />collected in all reaches include; 11 walleye, 11 green <br />sunfish, 1 black bullhead, and 17 channel catfish. <br /> <br />In the Green River, some additional electrofishing was done <br />in flooded tributary mouths where the concurrent sampling <br />for razorback sucker larvae is conducted. Millard Canyon, <br />Anderson Bottom and Holeman Canyon are located between <br />reach 5 and the elective reach. Sampling produced 3 <br />subadult and 3 YOY Colorado squawfish. Of particular <br /> <br />2 <br />
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