9641

• UCREFRP Catalog Number: 9641
• Author: Hedrick, T. N., K. R. Bestgen and K. D. Christopherson.
• Title: Entrainment of Semi-Buoyant Beads and Razorback Sucker, Xyrauchen texanus, Larvae into Flood Plain Wetlands of the Middle Green River, Utah.
• USFW Year: 2009.
• USFW - Doc Type: C-6/RZ-ENTR,
• Copyright Material: NO

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samples at the site. Data were also used to estimate distance and travel rate of beads and larvae,

and spatial patterns and mixing of beads across the channel over the longitudinal distance

between capture sites.

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2006

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Consistent with changes in other years, the sampling design in 2006 was altered from

2005 to provide new information. Emphasis in 2006 was placed on understanding specific

entrainment rates at breaches of flow-through flood plain wetlands. This was accomplished by

releasing beads and larvae just upstream from (e.g., 1.6 km upstream), and near the channel

margin of, breaches of Thunder Ranch, Stewart Lake, and Bonanza Bridge wetlands. Stewart

Lake was limited to a single inflow with no outlet in 2005, but managers from the Utah Division

of Wildlife Resources (UDWR) (K. Christopherson, S. Brayton, UDWR, pers. comm.) assured

us that the outlet would remain open until Green River flow peaked in 2006. Thus, unlike during

2005 sampling, all sampling efforts in 2006 at Stewart Lake occurred during flow-through

conditions until peak flow in the Green River was reached, after which the outlet was closed.

Thus, no sampling was conducted at Stewart Lake during flows on the descending limb of the
hydrograph.

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Thunder Ranch

Approximately 540,000 beads were released upstream of each of the flood plain sites on
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various dates between 17 and 30 May in 2006. Tetracycline-marked razorback sucker larvae

were released only at Thunder Ranch and only on the first three sampling occasions, because

. numbers were insufficient for other releases there or at other locations. Yellow beads and larvae

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