9540

• UCREFRP Catalog Number: 9540
• Author: Christopherson, K., G. J. Birchell and T. Modde.
• Title: Larval Razorback Sucker and Bonytail Survival and Growth in the Presence of Nonnative Fish in the Stipprup Floodplain.
• USFW Year: 2004.
• USFW - Doc Type: Salt Lake City, UT.
• Copyright Material: NO

Razorback Sucker
Survival
On July 30, 2002, the area outside the enclosures was sampled to quantify the number of
razorback suckers that escaped the enclosures. The Schumacher and Eschmeyer method
produced an estimate of 1,113 fish with 95% confidence limits between 761 and 2,070 for
razorback suckers that escaped the enclosures (Table 2).
Similar results were obtained using the Peterson method. The estimated population was
1,512 fish with 95% confidence limits between 917 and 3,547 fish (Table 2).
Table 2. Total razorback sucker population estimate for The Stirrup floodplain wetland,
Green River (RM 276.0) in August 2002.
Schumacher and Eschmeyer Peterson
Nhat Lower Upper Nhat Lower Upper
Outside enclosures 1,113 761 2,070 1,512 917 3,547
a High-density 1,586° 1,586 1,773 1,709 1,704 1,896
a Low-density 319 276 445 402 359 528
b Control 98 n/a n/a 98 n/a n/a
Total 3,116 2,721 4,386 3,634 2,877 5,863
a Razorback sucker numbers used for this table are the population estimates with confidence limits for each
enclosure. b Control population is not an estimate. It is the total number recovered. ° Actual number offish captured
was used for the population estimate.
From July 30 to August 13, 2002, the enclosures were repeatedly netted to establish
depletion curves (Table 3 and Table 4).
In the low-density enclosure, the Peterson razorback sucker population estimate was 402
fish with 95% confidence limits between 359 and 528 fish (Table 2). Survival ranged from 0.62
to 0.87 percent (Table 5).
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