9383

• UCREFRP Catalog Number: 9383
• Author: SWCA, I.
• Title: Recovery Goals for the four Colorado River Endangered Fish Species.
• USFW Year: 2000.
• USFW - Doc Type: Logan.
• Copyright Material: NO

4.0 RECOVERY CRITERIA BY RECOVERY AREA

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systems that may allow them to excrete excess selenium efficiently, thereby maintaining
constant concentrations in their tissue. The primary effect of selenium on fish is
newly hatched have enlargened heads from fluid in the tissues. Most edemaceous
fish die swimup.
Selenium is hypothesized as a cause for the decline of the endangered fish and as a water
quality factor that continues to inhibit recovery by adversely affecting reproductive success and
recruitment (Hamilton 1998, 1999, Osmundson and Osmundson 2000). Studies of endangered
razorback sucker, . hen texanus, from Ashley Creek, a tributary ofthe Green River with 59-
IN
78 ug SelL (Hamiltt" Waddell 1994) showed selenium concentrations of 4.4-32 ug/g dry
'_A_/I~"." ?~%'*"-.
weight, and 3.7-10.6 ug/g dry weight from female muscle plugs and eggs, respectively. They
also reported 3.6-26 ug Se/g dry weight and 1.1-6.7 ug Se/g dry weight from male muscle plugs
and milt, respectively. Definitive effects were not demonstrated because of a lack of information
on the species in the wild (Hamiltonet al. 1999). However, possible effects on larval survival
was a concern; selenium concentrations of 3.7-10.6 ug/g are within the range of no adverse
effects (2.0-3.1 ug/g) and adverse effect -24 ug/g) on fish. Peltz and Waddell (1991) also
reported concentrations of 4.9-28 ug/ 'ght selenium from eggs of razorback sucker from
"Razorback Bar" on the mainstem Green River with waterborne concentration of about 1.5 ug
SelL. Relationships have not been established, but extensive declines in populations of
razorback suckers indicate possible effect on reproduction. An evaluation of selenium effects on
endangered fishes must be conducted, and necessary actions untaken if selenium is determined to
have a significant detrimental effect on survival and/or rec .

4.1 Humpback Chub

4.1.1 Site-Specific Management Actions To Achieve Recovery
The following are site-specific management actions necessary to recover the endangered
humpback chub by recovery area. Details of these and other actions that contributTovery
are identified in the Recovery Implementation Program Recovery Action Plan (RIPT of the
Upper Colorado River Recovery Program, and in the Annual Work Plans of the Grand Canyon

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