7834

• UCREFRP Catalog Number: 7834
• Author: Burdick, B. D. a. R. B. B.
• Title: Experimental Stocking Of Adult Razorback Sucker In The Upper Colorado And Gunnison Rivers.
• USFW Year: 1997.
• USFW - Doc Type: \
• Copyright Material: NO

and Gunnison rivers. The intent is to stock all surviving captive-reared
razorback sucker into the Gunnison and Upper Colorado rivers if fish meet the
"Genetics Management Guidelines" (Williamson and Wydoski 1994).
The major goal of this stocking is to re-introduce razorback sucker into
the Upper Colorado and Gunnison rivers and establish an adult population of 10
fish per river mile. In the Gunnison River, the target is to re-establish a
population of about 600 adult razorback sucker from Austin, Colorado, downstream
to the confluence with the Colorado River. In the Upper Colorado River, an
initial target is to re-establish a population of about 1,200 adult razorback
sucker between Rifle, Colorado, and Westwater Wash, Utah (Burdick et al. 1995).
Final goals for population parameters in the different reaches will be determined
from Recovery Program Management Objectives and the final recovery plan for
razorback sucker (FWS 1997). The second goal is to evaluate the relation between
survival of razorback sucker and size at release into the river. Other
objectives of this study will be to 1) determine the dispersal of stocked fish
of various sizes (4- and 8-12-inch) following release, 2) determine habitat use,
3) evaluate different gear for sampling juvenile and sub-adult razorback sucker,
and 4) provide recommendations for the optimum size(s) for stocking razorback
sucker into Upper Colorado River Basin rivers.
As part of this stocking effort, 316, 4-6-inch razorback sucker were
stocked in the Gunnison River (RM 59.3) in October 1995 immediately downstream
of Hartland Diversion Dam. None of these PIT-tagged fish have subsequently been
recaptured during followup monitoring. An additional 287, 9-16-inch razorback
sucker, offspring of San Juan River adult fish, were stocked 4 October 1996 in
the Gunnison River (RM 57.0) at Delta. Seven of the fish stocked in 1996 were
subsequently captured downstream of the stocking site one week later. The
furthest razorback sucker capture was 11 river miles downstream from the stocking
site.
RECOMMENDATIONS
Major recommendations (bolded print) are:
1. Stocking Sites. Stock fish as far upstream as possible. In the
Gunnison River, fish should be stocked immediately downstream of
Hartland Diversion Dam (RN 60.0); the most feasible stocking location
being Confluence Park boat launch (RH 57.1). In the Upper Colorado
River, fish could be stocked at Rifle (RN 240.7). Results of this and
other studies conducted in the San Juan River suggest stocking as far
upstream as possible due to the predominantly downstream dispersal of
fish immediately following release.
2. Size Number and Condition to Enhance Post-stocking :)urvivai.
Evaluate the survival and performance of different sizes of hatchery-
and pond-reared razorback sucker to be released over the next 4 years
in the Gunnison River to recommend the number and optimum size of
razorback sucker to be stocked in riverine environments to restore
populations in the Gunnison and Upper Colorado rivers. Determining
the optimum size of razorback sucker to stock should enhance post-
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