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<br />7 <br /> <br />RESULTS <br /> <br />Job 1. <br />Job 2. <br />Job 3. <br /> <br />Title: Gamefish species life history data <br />Title: Gamefish predation upon endangered fishes <br />Title: Northern pike habitat utilization <br /> <br />Results for the above Jobs are provided according to the Tasks outlined <br />above. Field work was performed as indicated below. <br /> <br />Task 1: A total of 17 individual backwaters were sampled between April 23 <br />and June 25, and 55 samples were taken. Ten backwaters were sampled more <br />than once; eight backwaters were sampled four times or more, and accounted <br />for 80% of the total number of samples taken. The fish capture data should <br />be adequate for evaluating the methodology and effects of pike and catfish <br />removal upon associated fishes. This data will be incorporated into the <br />existing backwater sampling/removal data. The data will demonstrate flow <br />levels at which adult fish use and vacate this habitat type, species <br />associations, and treatment effects. <br /> <br />Task 2: Attempts to establish predation on drifting Colorado squawfish <br />larvae by channel catfish in Yampa Canyon (Echo Park) have been unsuccessful <br />to date due to lack of drifting larvae (bad timing or no larvae) and <br />inability to capture juvenile channel catfish (wrong technique or low <br />abundance). This effort could be modified to include analysis of potential <br />CS larvae predation among nongame, non-native species like red shiner, and <br />would require an intensive field time commitment with no certainty of <br />obtaining satisfactory sample results. This was accomplished by CSU Larval <br />Fish Lab personnel in conjunction with ongoing drift net sampling associated <br />with Flaming Gorge studies. <br /> <br />, <br /> <br />Another approach was to intensively sample select backwater(s) in the <br />Colorado River in the Grand Valley in conjunction with drift ne.t sampling to <br />evaluate potential nighttime predation patterns and prey selectivity by <br />juvenile channel catfish. These efforts were performed by CDOW personnel in <br />July 1991 during the weeks of the 8th and 22nd. Four backwaters were blocked <br />with trammel nets and seined periodically from dusk into the evening. <br />Presence, relative abundance, and gut content of gamefish species collected <br />were examined for differences relative to similar parameters from daylight <br />standardized seine data. Drift net samples were collected concurrently to <br />document presence and abundance offish species as larval drift and as a <br />potential fish prey base to juvenile gamefish. Seventy-four juvenile fish <br />comprised of channel catfish, black bullhead, green sunfish, black crappie, <br />and largemouth bass were collected in eight seine hauls. Six dawn drift net <br />samples were collected. Analysis of these samples is continuing. <br /> <br />Additionally, stomach contents of gamefish species sampled during the fall <br />standardized seine sampling in the Colorado River in Colorado in 1990 were <br />analyzed for ingestion of fish prey. This sample consisted of 95 fish, and <br />included channel catfish, green sunfish, black bullhead, and largemouth bass <br />juveniles. <br />