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Last modified
7/14/2009 5:02:35 PM
Creation date
5/22/2009 6:55:41 PM
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UCREFRP
UCREFRP Catalog Number
9408
Author
Foster, D. K. and G. Mueller.
Title
Movement Patterns, Behavior, and Habitat Use of Razorback Sucker Stocked Into the Green River at Canyonlands National Park, Utah.
USFW Year
1999.
USFW - Doc Type
Open-File Report 99-107,
Copyright Material
NO
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<br /> h <br /> aut <br />ors report survival rates ofradio-tagged razorback suckers between 40 and 53%. <br /> Twenty-five of the 656 pit-tagged razorback suckers were recaptured during the first <br /> 6 months. The recapture rate ofpit-tagged fish is quite high when considering the large <br /> size of this study area and may indicate that the San Juan River is an excellent choice for <br /> future stocking of razorback suckers. However, since growth rates were low during the <br /> first 6 months following release (mean growth rate = .0105% of total length per % year), <br /> perhaps the aquatic food base available to the razorback sucker in the San Juan River is of <br /> poor quality or made partially unavailable due to competition with other fishes, the threat <br /> of predation, or some other factor. Or perhaps the low growth rates indicate that a <br /> substantial period of time is required for razorback sucker to make the transition from <br /> hatchery to turbid river. <br /> The survivorship of stocked razorback sucker has been increased by releasing relatively <br /> lazge fish (>250 mm) instead of larvae (10 to 20 mm) (Mueller 1995), however, adult <br /> razorback suckers stocked into rivers undertake large movements during the first weeks <br /> of liberation and often suffer high mortality. For example, the releases of adult razorback <br /> sucker made by Ryden and Pfeifer (1995) in the San Juan River, Burdick and Bonar <br /> (1997) in the upper Colorado and Gunnison Rivers, and Day and Modde (1999) in the <br /> Green River have shown that stocked razorback sucker will undertake movements <br /> directed downstream (0 to 80 km) during the first few weeks following their release. This <br /> directed movement downstream accounted for a combined 46 out of 91 (50.5%) <br /> razorback suckers departing the two sites targeted for their introduction. Exceedingly few <br /> suckers (4 of 91) were observed to move upstream from their release points. Downstream <br /> emigration combined with fatalities (27 fish] have contributed in part to the difficulty in <br /> creating and maintaining viable, reproducing populations of razorback suckers in the <br /> habitats deemed to be suitable, as listed in the razorback sucker recovery plan (Tyus <br /> 1998). Researchers have suggested that stocked fish should be "...stocked as far <br /> <br />'~ upstream as possible" (Burdick and Bonar 1997, Ryden and Pfeifer 1996) . This <br />suggestion does have merit considering the propensity of razorback suckers to initially <br /> move downstream from a stocking site, but this technique requires that a great many <br /> individuals be stocked at a far distant location due to the low probability that a particular <br /> fish will survive, move downstream a set distance, and become a resident in a targeted <br /> section of river. <br />This project assessed movements and habitat use of razorback sucker stocked in the <br />Green River, Canyonlands National Park, and tested pre-stocking acclimation as an <br />alternative method to "upstream stocking," as suggested by Burdick and Bonar (1997) <br />and Day and Modde (1999). The study was directed at determining the practicality of <br />reestablishing/augmenting a viable population of razorback sucker into the Green and <br />Colorado Rivers within Canyonlands National Pazk. <br />Two groups of 15 razorback suckers were compared: an acclimated group held in a <br />backwater for ~2 days, and a second group handled identically and placed immediately <br />1 <br />3 <br /> <br />
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