8059

• UCREFRP Catalog Number: 8059
• Author: Burdick, B. D. and F. K. Pfeifer.
• Title: Discussion Of The Merits For Fish Passage At Hartland Diversion Dam On The Gunnison River Near Delta, Colorado-Final Report.
• USFW Year: 1996.
• USFW - Doc Type: Grand Junction, Colorado.
• Copyright Material: NO

Fish Community
Native Fishes
Upstream of the Redlands Diversion Dam (river mile 3), native fishes comprised
approximately 79% of all fishes collected with electrofishing during a recent riverwide inventory
(Burdick 1995). The predominant native fishes include bluehead sucker (Catostomus discobolus),
flannelmouth sucker (C. latipinnis), and roundtail chub Gila robusta (Burdick 1995). The
Gunnison River upstream of the Redlands Diversion Dam is currently occupied by a small
enclave population of Colorado squawfish and is historical habitat for the razorback sucker and
bonytail (G. ele ans . Five adult Colorado squawfish were captured upstream of Redlands
Diversion Dam in the Gunnison River during fishery surveys conducted in 1993. In the summer
of 1993, one radio-tagged Colorado squawfish was located about 0.2 mile downstream of
Hartland Diversion Dam.
No razorback sucker were captured during this two-year survey. The last documented
capture of an adult razorback sucker from the Gunnison River was 1981 near river mile 53
(Johnson Boy's Slough area) (Holden et al. 1982). Hartland Diversion Dam presently bisects a
17-mile long floodplain of the Gunnison River between Roubideau Creek (river mile 50) and
Austin (river mile 67). Although razorback sucker appear to be extirpated from the Gunnison
River, this 17-mile reach is considered a priority razorback sucker restoration site because it is
the only flooded bottomland habitat that exists in warmwater reaches of the Gunnison River.
Historically, the upstream range and distribution of the razorback sucker in the warmwater
reaches of the Gunnison River are unknown. However, historical accounts indicate razorback
sucker were found both up- and downstream of Hartland Diversion Dam (Quartarone 1993;
Personal communications, Kenneth Johnson, Wendell Johnson). How the razorback sucker
actually utilized the reach upstream of Hartland Diversion Dam is uncertain, but based on
floodplain habitat availability, it may have been used for spawning. Today the transition from
cold-water species (e.g., salmonids) to warmwater species (e.g., flannelmouth and bluehead sucker
and carp Cyprinus c io) is considered between the confluence with the North Fork (river mile
75) and Austin. Conceivably, the upstream range of the razorback sucker could be the confluence
with the North Fork because both the native flannelmouth sucker and bluehead sucker are
abundant upstream to this point.
Nonnative Fishes
Three nonnative small-bodied species, fathead minnow Pime hp ales promelas, sand shiner
Notropis stramineus, and red shiner Cyprinella lutrensis, are prevalent in the Gunnison River
upstream of Redlands Diversion Dam. During seining surveys conducted during 1992 and 1993,
these three species accounted for approximately 60% of all fish collected (Burdick 1995). In the
reach immediately downstream from Hartland Diversion Dam, fathead minnow and sand shiner
are abundant whereas red shiner and plains killifish Fundulus zebrinus are common and rare,
respectively. A very positive factor for razorback sucker reestablishment in the Gunnison River
is the absence of channel catfish Ictalurus punctatus. Other piscivorous fishes that are rare to
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