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I)qntl~",.. !b , Study Title: Stream Fisheries Investigations Job No. 2 Job Title: Wild Trout Introductions Job Objective: To establish, then quantitatively describe, wild rainbow trout populations in the upper Gunnison (Almont to Gunnison), Rio Grande (above Creede to Del Norte), Animas (at and downstream from Durango), and Blue rivers (between Dillon and Green 'Mountain reservoirs). Period Covered: July 1, 1987 through June 30, 1988 INTRODUCTION New documentation' was written for Federal Aid Project F-5l (Stream Fisheries Investigations) to cover a 5-year study plan from July 1, 1987 through June 30, 1992. Under the old documentation (l982-87) the study entitled, "Wild Trout Introductions," was designed as Job ,4'. Under the new documentation (1987-92), this job is designated as Job 2. The number of study st~eams has been expanded from one, the Rio Grande River,to four. The three streams added to the study are the Blue, upper Gunnison, and Animas rivers, as shown in the job objective. Elect~oshocking surveys on some of the larger trout streams, such as the- Rio Grande and Arkansas rivers,have shown brown trout to be the dominant species of salmonid almos't to the exclusion of othersalmonids such as the rainbow. Yet, our studies on many other streams where special 'regulations (Nehring 1987) have been used to protect the vulnerable rainbow stocks from over-harvest by anglers, reveal that rainbow populations will actually thrive, and in many cases, outcompete and outproduce brown trout. We have observed dramatic changes from brown trout dominance in streams managed under an eight trout/day angling limit to rainbow dominance 3-5 years after 'imposition of restrictive angling regulations., Rainbow trout become numerically superior to the'browns in biomass, density; and numbers of quality size (35 cm or l4 in.) trout. Rainbows also provide a catch rate from 3-5 times greater than the brown trout on a per fish basis. The objectives of Colorado's Gold Medal Trout Management program are threefold: l. Maintain trout biomass at 45 kg/ha (40 lb/ac). 2. Maintain quality trout density (~35 cm or l4 in.) at 30/ha (l2/ac) on a sustained basis. 3. Maintain total catch-per-man-hour (CPMH) at 0.7 trout/hour or higher. With these objectives in mind, it is almost a necessity that our gold medal waters be managed with a rainbow coexisting in sympatry with the brown trout. The second and third objectives are difficult to meet on a sustained basis with allopatric brown trout populations. ' --;,; . ." ,~ ;'~'f IJ 00002397