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Last modified
7/14/2009 5:02:32 PM
Creation date
5/22/2009 5:23:56 PM
Metadata
Fields
Template:
UCREFRP
UCREFRP Catalog Number
7980
Author
Archer, D. L., H. M. Tyus and R. Valdez.
Title
Field Methodologies of the Fish and Wildlife Service's Colorado River Fisheries Project.
USFW Year
1980.
USFW - Doc Type
Denver, Colorado.
Copyright Material
NO
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<br /> <br />I <br /> <br />17 <br /> <br />A radio tagging program is to be initiated to better follow <br />spawning behavior of squawfish and to define specific spawning areas <br />so as to determine the constituents of spawning habitats. <br /> <br />An assessment of disease organisms affecting the endemic as well <br />as the introduced species will be carried out during 1980. These <br />investigations will be conducted on a cursory plane by field crews and <br />intensively by a group of disease specialists who will sample all <br />major components of the populations in both rivers three times a year <br />for all major pathogens and parasites. <br /> <br />Humpback chub YOY studies and movement patterns will be addressed <br />by our team in cooperation with the Colorado Division of Wildlife. <br /> <br />Equipment <br /> <br />The field teams were faced with the very challenging task of <br />effectively sampling a very extensive river system under some very <br />difficult conditions. To do this the most advanced technological <br />equipment was utilized to collect fish and to measure the associated <br />chemical and physical parameters (Appendix A-2). <br /> <br />The effectiveness of electroshocking equipment is diminished <br />substantially by the high conductivities, great depths and high <br />turbidites. However, a unit was developed using a rotating field with <br />pulsed DC current which was reasonably effective under most conditions. <br />The unit used a 4.0 kilowatt generator as a power source. A smaller <br />unit of 1.8 Kilowatts was developed for use on a raft, but it had very <br />limited effectiveness. Fish collection with the larger unit was <br />generally most.effective at 200-250 volts and 8 to 12 amps. Condunctivities <br />fluctuated extensively requiring continual adjustment of the electrical <br />equipment and electrodes. This gear was especially useful in collecting <br />squawfish which appeared to be more vulnerable to electroshock than <br />most of the other species. <br /> <br />Trammel nets were set in the slow-flowing pools and eddies. They <br />of course often collected much debris but were effective on squawfish, <br />chubs, suckers, catfish and carp. They rarely caught intermediate and <br />small fishes. Because fish generally succumb in this gear after a <br />short while, They were tended regularly every two to three hours. <br />Gill nets were only occasionally used because they have been credited <br />with being more lethal to fishes. This, however, was not borne out in <br />our experiences and we feel that in all likelihood they are less <br />destructive to the rare fishes than trammel nets. <br /> <br />The trammel nets we utilized were 150 ft long x 6 ft deep and of <br />1 in and 1.5 in bar mesh of #139 twine with a wall of 10 to 12 in bar <br />mesh. <br /> <br />Funnel-type wire mesh traps of 1 in chicken wire approximately <br />1.5 ft in diameter by 2 1/2 ft long were very effective when set among <br />large boulders or accumulations of debris in catching catfish and the <br /> <br /> <br />
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