Balancing Change and Tradition: Fishery Management at Rifle Gap Reservoir in Northwest Colorado

Rifle Gap Reservoir (Garfield County, Colorado) is a popular, sport-fishery (cold and cool water fishes) during the open-water and ice fishing seasons.  The 360 surface acre reservoir was constructed during the mid-1960's for agricultural, recreational, and fish and wildlife purposes.  The fish assemblage has changed over time, due primarily to illicit fish introductions.  Four fish species (rainbow trout, brown trout, smallmouth bass, and walleye) occupied the reservoir in 1974 with six additional fish species present in 2009.  Yellow perch and northern pike are recent invaders, with "quality" to "memorable" yellow perch (8 to 12 inches) and "quality" to "trophy" northern pike (21 to 44 inches) available.  Angler fishing preferences (species targeted) and behaviors (harvest versus catch-and-release) have transformed as a result of these fish assemblage changes.  The CDOW completed angler creel surveys in 1987 (April-July) and 2009 (May-October) during the open-water season.  Angler hours in 2009 decreased 32% from 1987, despite three additional survey months in 2009.  Angler catch per hour, however, tripled from 1987 (0.6) to 2009 (1.8).  Rainbow trout (30,291 fish) comprised 80% of the total catch in 1987, and only 11% (8,014 fish) in 2009.  Yellow perch dominated angler catch in 2009, constituting 82% (61,185 fish) of the total catch.  More anglers practiced catch-and-release in 2009 (56% of fish caught were released) than in 1987 (22% of fish caught were released).  Only 8% of rainbow trout caught in 1987 were released compared to 52% in 2009.  The CDOW also completed an ice fishing creel survey from December 2009-February 2010.  Yellow perch comprised 86% of the total catch by ice anglers.  These anglers also released fewer fish (25% of fish caught were released) in comparison to open-water anglers.  Balancing modifications to the reservoir's fish assemblage, and addressing traditional angler behaviors are several challenges the CDOW faces in developing a biologically sound fishery management plan for Rifle Gap Reservoir.  Additional issues include reservoir fish stocking restrictions due to downstream critical habitat for native, federal-listed and non-listed fishes; potential operations change at Rifle Gap State Park due to budgetary concerns; and sport-fish consumption advisories for mercury.