9447

• UCREFRP Catalog Number: 9447
• Author: Burdick, B. D.
• Title: Evaluation of Stocking Sub-Adult Colorado Pikeminnow Via Translocation in the Upper Colorado River Between Palisade and Rifle, Colorado.
• USFW Year: 2003.
• USFW - Doc Type: 105,
• Copyright Material: NO

us to suspect none of the five domestic-reared fish implanted with radio transmitters in 2000
survived long following release (Figwe 4), None of the 55 other domestic-reazed Colorado
pdceminnow from the 1991 year-class nor any of their five radio-tagged counterparts were seen or
collected during sampling in mid-July of 2000 and 2001 using electrofishing in the Upper
Colorado River from Rifle to the Westwater boat landing in eastern Utah (Bwdick 2003). None
of these fish nor the 246 other juvenile Colorado pikeminnow stocked at RM 229.9 in the Upper
Colorado River in late-May 2001 have been subsequently reported during other Recovery
Program sampling activities during 2000, 2001, or 2002. However, post-stocking survival of
hatchery-reared fish used in experimental stocking (Valdez et al. 1982; Archer et al. 1985;
Bwdick 2003), reintroduction programs (Ryden 2000), and telemetry studies (Chart and Cranney
1993; Modde and Meyer 1991) in mainstem rivers of the Upper Colorado River Basin has been
low.
Holding domestic-reared Colorado pdceminnow in the kettle at Horsethief SWA following
radio-transmitter implantation may not have been prudent and could have stressed them further.
Following capture in the Colorado River and transport to Horsethief SWA, all five wild Colorado
pikeminnow were also held in the kettle for about 2 weeks prior to being implanted with radio
transmitters. The kettle has been used in the past to temporarily hold and sort razorback sucker
broodfish. However, both the wild and domestic-reazed Colorado p~ceminnow may have been
held too long in the kettle. This may have compromised the ability of the wild radio-tagged fish
to readjust following stocking and the ability of the five domestic-reared radio-tagged Colorado
pikeminnow to acclimate to a river environment. Furthermore, this may have affected movement
behavior; none of the domestic-reared Colorado pikeminnow that were radio tagged and released
were detected exhibiting upstream movement. Results from fish radio tagged and released in
2000 should, therefore, be treated with caution.
Fish Radio Tagged in 2001
Contact was maintained with this group offish 19-403 days following release. Twelve fish
exhibited upstream river movement (mean=8.1 miles; range=0.3-22.6) following release.
However, none of these fish were ever detected upstream from the stocking point. The mean
downstream river movement for these 19 fish was 40.3 miles (range=3.2-77.2) (Table 2). During
a short 13-day period in mid-June 2001 (13 25), seven different radio-tagged wild Colorado
pikeminnow (Codes 135, 136, 137, 139, 147, 152, and 156) that were stocked earlier in May and
June were within 8.5 miles (RM 229.2-220.7) of each other. Five of these fish (Codes 135, 136,
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