9699

• UCREFRP Catalog Number: 9699
• Author: Brunson, R.E., and K.D. Christopherson.
• Title: Larval razorback sucker and bonytail survival and growth in the presence of nonnative fish in the Baeser floodplain wetland of the middle Green River.
• USFW Year: 2005.
• USFW - Doc Type: Utah Division of Wildlife Resources, Vernal, Utah.
• Copyright Material: NO

INTRODUCTION
The Upper Colorado River Endangered Fish Recovery Program (Recovery
Program) initiated floodplain restoration on the Green River in 1996 (Birchell et al.
2002). Restoration was based on information that floodplain wetlands may provide
critical rearing habitat for endangered fish, primarily razorback sucker (Wydoski and
Wick 1998; Modde 1996 and Modde et al. 2001). The goal was to restore natural
floodplain wetland habitats and functions that support the recovery of razorback sucker
(Lentsch et al. 1996). Restoration to improve floodplain function includes mechanically
lowering levees at selected wetlands to increase frequency of the river-floodplain
connection to pre-Flaming Gorge Reservoir levels (Birchell et al. 2002).
Research questions following floodplain habitat restoration were the focus of
other studies (Birchell and Christopherson 2004, Christopherson et al. 2004), Including:
1) Can razorback sucker larvae be entrained in floodplains by lowering
levees to improve the river-floodplain connection?
2) Can larvae be entrained at high enough numbers to ensure survival
from predation by nonnative fish and predacious insects?
3) Will razorback sucker survive, voluntarily migrate from the floodplain
during high flows, and recruit into the river population?
4) What cues trigger migration from the floodplain?
To help answer the latter three questions, projects were proposed to evaluate
survival and growth of larval razorback sucker and bonytail by experimentally
introducing them into controlled enclosures. A study completed in 2002 at The Stirrup