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

factor. The survival reported was likely affected by the high density of larval fish in the control
enclosure resulting in an outbreak of Ichthyophthiriasis.
i
Table 5. Larval razorback sucker survival estimates with 95% confidence limits for low- ~
density, high-density and control enclosures at The Stirrup floodplain wetland,
Green River (RM 276.0) July 30-August 13, 2002.
Enclosure Survival Estimate Lower Limit Upper Limit
Low-density 0.67% 0.62% 0.87%
High-density 0.37% 0.37% 0.41 % ~
Control 10.8% NAe NAe
a Confidence intervals not applicable because we assumed all fish were removed from the control enclosure.
Growth
Growth rates varied for the different treatments suggesting density dependence. On June
a
27, asub-sample of 29 razorback suckers was taken from the low-density, and 157 from the
high-density group. The mean total length for the high-density group was 27.7 mm, for the low- ~
density group it was 33.2 mm.
On July 23-30, razorback suckers collected outside the enclosures averaged 90 mm.
During depletion sampling (July 30-August 13) razorback sucker in the low-density enclosure
averaged 69 mm, in the high-density enclosure they averaged 58 mm, and in the control
enclosure they averaged 69 mm.
At the end of the study (October 8, 2002), razorback suckers that had been released into
the main wetland had grown to an average length of 163 mm, with a range of 95-294 mm. The
average growth per day was 1.1 mm for the 139 days of the study. ~

12 ~