7796

• UCREFRP Catalog Number: 7796
• Author: Burdick, B. D.
• Title: Conceptual Management Plan for Habitat Enhancement in Flooded Bottomlands, Escalante State Wildlife Area, Gunnison River Downstream of Delta, Colorado.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

' lithium, uranium, selenate, and boron) suggest a high toxicity to the swim-up fry
of hatchery-reared razorback sucker, Colorado squawfish, and bonytail (Appendix
C). Toxicity tests were conducted in water that simulated conditions in the
middle Green River near Jensen, Utah. This area had elevated concentrations of
some trace elements in water, bottom sediments, and biological tissue (fish,
aquatic invertebrates, and plants).
The next logical step would be to conduct in situ bioassays using the most
vulnerable life stages of the species of concern. It is beneficial to have a
site to conduct in situ studies to access bioaccumulation in and toxicity of
selected elements to target endangered fishes. This may provide some answers to
determine if trace elements are limiting the survival of this species.
Razorback sucker of different sizes ranging from post-larvae to fingerlings
could be stocked into Site 1 at the Escalante SWA. Larvae of two other native
suckers (flannelmouth and bluehead) could also be stocked in this site for in
' situ bioassays. Fish used in these studies would be progeny from upper Colorado
River stock. A small sample of fish could be retrieved and sacrificed for
contaminant analysis at various intervals until the fish reach maturity.
Attempts would be made to monitor chronic effects of trace elements. A
laboratory would serve as the control site. In the laboratory, the
concentrations and combinations of the various trace elements could be
' controlled. The warmwater, productive area should grow fish rather quickly.
Fish would probably reach maturity in about 2-1/2 years following stocking.
After reaching maturity, gametes and F, progeny from these fish reared in this
site could be analyzed for selected trace elements. The bioaccumulation and
' concentration of trace elements thought to be harmful could be analyzed and
compared among life stages and among the three native sucker species for both the
control and "on-site" studies. The on-site or in situ studies would allow
' assessment of dietary uptake of potential trace elements and their impacts to the
three native sucker species. In the laboratory studies, growth and reproductive
"vigor" of these three native sucker species subjected to the various trace
' elements (singly or in combination) and concentrations could be compared to the
control group (subjected to 'background concentrations' of trace elements).
Contaminant biologists would be responsible for designing and conducting these
in situ studies.
' This information is critical in determining if selenium or other trace
elements contribute to mortality of razorback sucker in the Gunnison River. If
toxicity concentrations of these trace elements are shown to be deleterious to
' certain life stages, attempts will be made to remedy the accumulation of trace
elements that are harmful to the endangered fishes. This information will be
' useful a
be used s screening criteria for selection of a site
for recover or river reach that could
y.
Information on survival of razorback sucker stocked at various sizes from
' larvae to fingerling and in the presence or absence of predatory non-native fish
that occur in the river could be evaluated at this site. The three compartments
would allow replicate experiments to be conducted with controls. Also, fish
' stocked as larvae could be reared and tagged for restoration stocking of the
Gunnison River. Tagging and marking endangered fishes will follow Program
protocol. Food production and invertebrate indices would be monitored seasonally
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