9559

• UCREFRP Catalog Number: 9559
• Author: Martinez, A. M.
• Title: An Evaluation of Nonnative Fish Control Treatments in Ponds along the Colorado and Gunnison Rivers, 1996-2002.
• USFW Year: 2004.
• USFW - Doc Type: 18/19,
• Copyright Material: NO

' either 1/4" or 3/16" mesh; 5 steel hoops - 2' diameter; 3 tapered throats on 19, 2'd and
3`d hoops; 25' lead; treated). Trammel nets were set for no more than three hours to
' avoid potential mortality to endangered fish. Fyke nets were set over night. Seine hauls
were done in small bays or along shallow shorelines.
All fish sampled were identified and in most cases weighed in grams (g) and the
total length was measured in millimeters (mm). When large numbers of fish were
collected, a subset of fish was weighed and measured and the remainder were
identified and enumerated.
Native Fish Salvage -- Citizens expressed concern regarding the impact of
nonnative fish removal on the availability of food for piscivorous birds (USFWS 1998a).
' To address this concern, native fish were salvaged from the Lewis Wash siphon in the
Government Highline Canal (1999, 2000, 2001, and 2002) immediately after the canal
' was drained in the fall. By stocking these fish into a reclaimed pond and an isolated
oxbow of the Colorado River they were made available to piscivorous birds. Excess
salvaged native fish were stocked directly into the Colorado River.
Nonnative Fish Control - NNFC techniques included chemical reclamation
(liquid/powder rotenone or chlorine), installation of pond outlet/inlet screen(s), water
management, use of black plastic, and/or rerouting irrigation water. Individual control
treatments were determined following consultation with landowners and evaluation of
' site specific constraints. NNFC treatments took place an average of 7.8 months post-
sampling. However, due to access constraints treatment dates ranged from two days to
' 50 months post-sampling. Powder rotenone (a restricted-use pesticide) and chlorine
were most often applied from boats by gasoline powered pump-eductor systems.
' However, for ponds that were inaccessible to vehicles, liquid rotenone was dripped off
the back of a cataraft. Sand mix (sand coated with rotenone and gelatin) was also
' applied to difficult-to-reach areas such as seeps and dense vegetation (Spateholts and
Lentsch no date). Ponds with outlets were pumped down prior to piscicide treatment to
prevent the movement of toxicant out of the treatment area.
Industry standards concerning the use of rotenone were followed (Cailteux et al.
' 2001, Finlayson et al. 2000). Piscicides were applied in accordance with manufacturer's
labels and local, state, and federal regulations regarding the application of restricted-
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