9442

• UCREFRP Catalog Number: 9442
• Author: Muth, R. T. and T. E. Czapla.
• Title: Workshop Summary
• USFW Year: 2002.
• USFW - Doc Type: Designing Methods to Evaluate Stocked Fish in the Upper Colorado River, Green River, and San Juan River Subbasins.
• Copyright Material: NO

Return of razorback sucker < 200 mmTL was low (~4.8%); therefore post-stocking
survival of razorback sucker of this size in the wild was presumed low (Figure 4).
The 200-249 mm TL size class had the highest return (~29%); this was ~21 % of all
razorback sucker stocked during 1995-2000 (Figure 4).
The 250-499 mm TL size class accounted for 64% of the total number (n = 84) of
razorback sucker captured during 1997-2001; this was about 8% (3,549) of the total
number stocked (n = 43,700+) during 1995-2000 (Figure 4).
Lot 1992-2A had a higher return rate than any other family lot stocked; the mean TL at
stocking was 343 mm.
Greater returns and thus survival may be obtained by stocking larger razorback sucker
(> 200 mm TL).
Stocked razorback sucker were commonly captured from backwater habitats (65% of
occurrences) .
Dispersal following stocking was predominately downstream from the release site;
stocked fish are susceptible to downstream displacement. In the Colorado River mean
dispersal downstream (MDD) was 17.9 miles (for fish < 6 months at large) and 22.1
miles (for fish> 6 months at large). In the Gunnison River, MDD was 26.3 miles (for
fish < 6 months at large) and 73.8 miles (for fish> 6 months at large).

Razorback Sucker Stocked: April'94-0ctober 2001
Gunnisol\l & Colorado Rivers Combined
4" 6" 8" 10" 12" 16" 20"

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TOTAL LENGTH (mm)

Figure 3. Razorback sucker stocked in the Gunnison and Colorado rivers during April
1994-0ctober 2001.

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