9432 ‎(2)‎

• UCREFRP Catalog Number: 9432
• Author: Modde, T. and M. Fuller.
• Title: Feasibility of Channel Catfish Reduction in the Lower Yampa River.
• USFW Year: 2002.
• USFW - Doc Type: Vernal.
• Copyright Material: NO

1993). Northern pike can be consistently collected in low numbers upstream from
Delta (Burdick 1995; McAda 1997). Channel catfish are quite abundant and
widespread in the Upper Colorado River and Lower Gunnison River downstream of
Redlands Dam but are virtually absent upstream of the dam. Only one adult
channel catfish was captured during the 2-year survey in 1992-1993, another was
captured near Little Dominquez Creek (RM 30.6) in August 1997, and carcasses of
two individuals were collected on the upstream trash grates at the Redlands
passageway in 1999.
The upstream limit of distribution for the endangered Colorado pikeminnow
and razorback sucker in the Gunnison River is Hartland Diversion Dam (Burdick
1995; Burdick and Pfeifer 1996). Although fish have access to the full 57 miles
between the two dams, most pikeminnow have been located in the lower 35 miles of
the available habitat. These two reaches also contained most of the Colorado
pikeminnow captures and observations as well. During the 1992-1993 study, only
five Colorado pikeminnow were captured upstream of the Redlands Diversion Dam;
three were captured within a 0.2-mile reach (RM 33.5 to 33.7). During 1993 and
1994, six radio-tagged pikeminnow used most of the river between Redlands and
Hartland dams, but 48% of all radio contacts were made between RM 30-42 and 32%
were made between RM 15-29 (Burdick 1995). These same six radio-tagged Colorado
pikeminnow congregated in a short river reach between RM 30 and 35 during the
presumed spawning period (early- to mid-August) in 1993, with four fish located
between RM 32-33. In 1994 three of the same six radio-tagged pikeminnow had
converged to the same location as in 1993. Earlier investigations (Valdez et al.
1982; Wick et al. 1985; personal communication, Edmund Wick) captured Colorado
pikeminnow between RM 26.7 and 33. All of these investigators believed that the
reach between Dominquez Creek and Peeples Orchards (RM 30-34) was important for
this species. The population abundance of sub-adult and adult Colorado
pikeminnow in the Gunnison River upstream of the Redlands Diversion Dam was
estimated at N=13 (95% CI=9-31)(see Appendix; Table L.1.).
Larval Colorado pikeminnow have been collected up- and downstream of the
Redlands Dam in low numbers, and document the existence of a spawning population
in the Gunnison River. Larvae have been collected by drift nets immediately
downstream of the Redlands Dam in 1986 (Osmundson and Kaeding 1989), 1992
(Anderson 1994), and 1995 (Anderson 1999). Larvae have been collected
immediately upstream of the dam in 1995 and 1996 (Anderson 1999) and at
Bridgeport (RM 30) in 1994, 1995, and 1996 (Anderson 1999). The fact that larval
Colorado pikeminnow were collected at Bridgeport is evidence that Colorado
pikeminnow did spawn and reproduction occurred somewhere upstream. However, the
collections of larval pikeminnow, downstream from Bridgeport do not help pinpoint
specific spawning sites because larvae could have drifted downstream for an
unknown distance before being collected.
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