Laserfiche WebLink
<br />(summer 1993, Colorado and Gunn i son rivers); and 3) sei ne (YOY) and <br />drift-net (larvae) samples collected as part of Aspinall studies by USFWS <br />and the state of Colorado (summer 1993 and 1994 and fall 1993, Colorado <br />and Gunnison rivers), When processing is completed, data reports <br />(including dBase computer files) summarizing results for each study are <br />submitted to appropri ate researchers. After process i ng, sampl es are <br />stored at LFl. <br /> <br />Flow-Effects Collections: <br /> <br />Colorado and Gunnison Rivers, Summer 1993: <br /> <br />A total of 255 samples were received for processing. To date, all <br />collections have been preliminarily identified and about 25% verified. <br />Collections will be counted and measured in 5-mm length-frequency groups <br />by species and all Gila will be individually me~sured and examined for <br />dorsal and anal fin-ray counts. All preliminarily identified Colorado <br />squawfish have been verified, individually measured, and preliminarily <br />reported. Only six specimens were identified as Colorado squawfish; two <br />of these are tentative identifications (possibly chubs with high myomere <br />counts). These specimens measured 10-14 mm TL and were coll ected at <br />Colorado River Miles 148,4, 137.4, 90.3, 39,1, 32.5, and 32.4 between <br />July 28 and August 19, No probable razorback suckers were identified. <br /> <br />Colorado and Gunnison Rivers, Summer 1992 (backlog under FY 93 funds): <br /> <br />Data summarized and submitted. A total of 240 larval-fish collections <br />for Colorado River Miles 184,6 to 3,2 (above confluence with Green River) <br />and 16 larval-fish collections for Gunnison River Miles 3,0 to 1.2 (above <br />confluence with Colorado River) taken during 29 June through 21 August <br />1992 (256 collections together). The collections contain 103,226 <br />preserved fish (an average of 403 specimens per collection) representing <br />13 species, Minnows account for 92%, suckers 7%, livebearers 1% and the <br />remaining two families (killifishes and sunfishes) just 0.03% of all fish <br />preserved, Only 15% of all fish (8% cyprinids, 7% catostomids) are <br />native species. Percentage compositions for the more abundant species <br />are 53% for red shiner, 19% for sand shiner, 10% for fathead minnow, 7% <br />for speckled dace, and 6% for bluehead sucker, Chubs, measuring 10-37 mm <br />total length, account for 1% of all fish collected. Based on fin-ray <br />counts, most are roundtail chub, Most were collected above Colorado <br />River Mile 80 in early and mid July; 31% were taken from the Gunnison <br />River. No .obvious. razorback suckers were identified. Non-cypriniform <br />fish are represented only by mosquitofish, plains killifish, and green <br />sunfish. <br /> <br />Eight-five Colorado squawfish were collected from the Colorado River and <br />none from the Gunnison River; 84 were larvae measuring 9-23 mm total <br />length and 1 was a juvenile measuring 27 mm (River Mile 9.8, 13 August). <br />Two recently hatched specimens (9-10 nun TL) were taken between River <br />Miles 153 and 155, one on 7 July and the other on 16 July. All remaining <br />larvae were collected from g July to 13 August (9-10 mm specimens as late <br />a 30 JulY) below River Mile 99. The largest aggregations were taken <br />between River Miles 45 and 13 on 15 July and at River Mile 19.2 on 30 <br />July, <br /> <br />2 <br />