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Last modified
7/14/2009 5:02:36 PM
Creation date
5/22/2009 5:00:55 PM
Metadata
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UCREFRP
UCREFRP Catalog Number
9533
Author
Muth, R. T. and E. Wick.
Title
Field Studies on Larval Razorback Sucker in Canyonlands National Park and Glen Canyon National Recreation Area, 1993-1995.
USFW Year
1997.
USFW - Doc Type
Fort Collins.
Copyright Material
NO
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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />~J <br /> <br /> <br />EXECUTIVE SUMMARY <br /> <br />Field studies on larval razorback sucker Xyrauchen texanus were conducted during <br />sprin -'1-993-1995 in reaches of the lower Green River and middle Colorado River <br />(1994 only) within or bordering Canyonlands National Park and in the Colorado River inflow to <br />Lake Powell within Glen Canyon National Recreation Area as part of a three-year National Park <br />Service, Rocky Mountain Region endangered-fish program for Colorado River basin parks <br />funded by the Natural Resource Preservation Program. Studies included (1) fish collections <br />using floating quatrefoil light traps and seines in nursery habitats, (2) description of the diet of <br />adult nonnative red shiner Cyprinella lutrensis captured in the lower Green and middle Colorado <br />rivers (1994), (3) initial evaluation of a method to at least partially block access of adult red <br />shiner into portions of important larval razorback sucker nursery habitats on the lower Green <br />River using net exclosures (1995), (4) field marking of sucker larvae using techniques <br />developed in the laboratory for incorporating fluorescent chemicals into otoliths (1995), and (5) <br />use of enclosures to evaluate growth and survival of wild razorback sucker larvae in nursery <br />habitats on the lower Green River (1995; study was planned, described in methods, but not <br />conducted due to low numbers of sucker larvae collected). <br /> <br />Results and Conclusions <br /> <br />. Nonnative minnows (e.g., red shiner, sand shiner Notropis stramineus, and fathead minnow <br />Pimephales promelas) dominated all fish collections (76 to > 99% of total number of fish <br />collected in each sampling area over all sampling periods). Native fishes collected include <br />larval razorback sucker (185 total; 122,47, and 1 from the lower Green River in 1993, 1994, <br />and 1995, respectively; 15 from the Colorado River inflow to Lake Powell in 1993), and larval <br />and early juvenile Colorado squawfish Ptychocheilus lucius (12 larvae and 133 juveniles total; <br />12 larvae from the Colorado River inflow to Lake Powell in 1993; 1, 36, and 82 juveniles from <br />the lower Green River in 1993, 1994, and 1995, respectively; 6 and 5 juveniles from the <br />Colorado River inflow to Lake Powell in 1993 and 1994, respectively; 3 juveniles from the <br />middle Green River in 1994). Of the 185 razorback sucker larvae collected, 168 were captured <br />in light traps and 17 (from the lower Green River) in seines. The Colorado squawfish larvae <br />were captured in light traps and juveniles were captured in seines. <br /> <br />. The capture of razorback sucker larvae in the lower Green River, combined with data from <br />Colorado River Recovery Program Flaming Gorge and razorback sucker monitoring studies, <br />strongly suggests localized spawning. <br /> <br />. Collections of razorback sucker and Colorado squawfish larvae from the Colorado River <br />inflow to Lake Powell in 1993 suggest that flowing, lotic conditions throughout the inflow are <br />necessary for larval transport into nursery habitats from upstream river reaches. <br /> <br />. Larval suckers were efficiently and accurately identified alive in the field, but procedures for <br />successfully transporting wild razorback sucker larvae captured in remote areas (e.g., lower <br />Green River) to rearing facilities require further development. <br /> <br />. Digestive tracts of 22 adult red shiner (5% of those examined) contained cypriniform fish <br />larvae, most were catostomids. Insects, including parts, chironomid larvae, simulid pupae, and <br /> <br />vi <br />
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