7402

• UCREFRP Catalog Number: 7402
• Author: Nesler, T. P.
• Title: Aquatic Nongame Research, Endangered Fishes Investigations.
• USFW Year: 1989.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

Upper Colorado River Endangered Fishes Recovery Implementation Plan was
dropped as a job objective from this study. This survey responsibility has
been assumed by Colorado Division of Wildlife (CDOW) fish management
biologists in the Northwest Region office in Grand Junction, Colorado. The
standardized monitoring survey was incorporated into this study's sampling
design to exploit a potential data source, but experience demonstrated adult
warmwater gamefish species were not efficiently captured by the spring
electrofishing approach. Spring sampling efforts are still coordinated with
CDOW NW Region biologists to avoid back-to-back sampling of the same river
reaches in the Colorado and Yampa rivers by both monitoring and research

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Also, the White and Dolores rivers were dropped from the study area due to
time and manpower limitations. The Yampa and Colorado rivers remain as the
primary study areas. Potential duplication of effort with NW Region fish
management biologists resulted in the job objective regarding warmwater
fishery losses to be dropped from the study also. Directives issued by the
Colorado Division of Wildlife in 1987 required stringent control of warmwater
gamefish stocking in waters associated with endangered fishes habitat in
western Colorado. Jhis prompted NW Region fish management to begin to assess
the magnitude and quality of warmwater fisheries affected by these
limitations.
As a result of these changes, the focus of this study was narrowed,
permitting concentration upon interactions between non-native gamefish and
endangered fish. Field sampling was expanded with more field trips to the
Yampa River to conduct radio tracking of implanted northern pike and sampling
of northern pike and channel catfish populations for life history data.
Standardized seine sampling in the Colorado River for"young-of-the-year
Colorado squawfish during the fall remains as part of the sampling strategy of
this study due to consistent captures of small centrarchids and ictalurids.
In addition, two jobs were added that involved short-term funding assistance
and contract supervision. These were the publication of a taxonomic key for
larvae and early juveniles of most catostomid species in the Upper Basin,
including the razorback sucker, and also a pilot study to determine habitat
use by endangered fishes in the Little Snake River. The normal reporting

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