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Last modified
7/14/2009 5:02:32 PM
Creation date
5/17/2009 11:15:16 PM
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UCREFRP
UCREFRP Catalog Number
8025
Author
Valdez, R., et al.
Title
Colorado River Fishery Project, Tributary Report (Gunnison and Dolores River) Final Report.
USFW Year
1982.
USFW - Doc Type
Grand Junction, CO.
Copyright Material
NO
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<br />5 <br /> <br />conducted through 3/8-in. stainless steel strand cable at a ratio of 1-3 <br />cathodes to 1 anode, depending on river conductivity. Electrofishing was <br />the most successful at output levels of 250-300 v with 10-15 amp of <br />current. <br /> <br />Trammel nets <br /> <br />Trammel nets used were 150 ft long and 6 ft high with I-in. mesh on <br />the inner panel and 10-in. mesh on outer panels. TIlese nets were set for <br />1-3 h during the day and overnight. Trammel nets fished effectively, <br />especially during conditions of high turbidity. <br /> <br />Gill nets <br /> <br />Several s~zes of gill nets were used during this study. Nets most <br />commonly used were 150 ft long x 6 ft high, with mesh sizes of 1.5, 2.0 <br />and 3.0 in. Experimental, monofilament gill nets O/2-in. and 3/4-in. <br />mesh) were also used. Nets were set 1-3 h during daylight hours and <br />overnight. Gill nets were not used as extensively as trammel nets <br />because they caused higher fish mortality. <br /> <br />Fyke nets <br /> <br />Fyke nets were used sparingly throughout this study because of <br />limited applic2bility in the reaches sampled. Fyke nets with double <br />wings were set in mouths of small streams entering the rivers. Fyke nets <br />with one center wing were set in tranquil pools during low flows. <br /> <br />Seines <br /> <br />Three seine sizes were used in the tributary study. Small seines (8 <br />ft x 3 ft with 1/8-in. mesh or 15 ft x 4 ft with" 1/4-in. mesh) were used <br />to capture young fishes and cyprinids of all ages in shallow areas. A <br />larger seine (30 ft x 6 ft with 1/2-in. mesh) was used to capture <br />juveniles and adults in deeper areas. <br /> <br />Fish Handling <br /> <br />Target Species <br /> <br />Special precautions were taken to insure survival of the target <br />fishes. Each endangered fish was carefully placed in a holding tub and <br />salt added to replenish electrolytes and thus reduce stress. The fish <br />was measured for total length (TL) in millimeters, weighed (grams) and <br />examined for external parasites, e.g. Lernaea sp. A red Carlin tag was <br />attached to the base of the dorsal fin of the fish. The small tag wounds <br />were treated with Betadine@ to deter infection. Scales were removed and <br />photographs were taken. The target species were released near the <br />original capture sites. <br />
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