7065

• UCREFRP Catalog Number: 7065
• Author: Behnke, R. J. and D. E. Benson.
• Title: Endangered and Threatened Fishes of the Upper Colorado River Basin.
• USFW Year: 1983.
• USFW - Doc Type: Bulletin 503A,
• Copyright Material: NO

Of young squawfish to 2 and 3 years of age when they
would become effective predators on the small non-
native fishes. The evidence of harmful effects of
non-native species on the squawfish is largely cir-
cumstantial and much is yet to be learned on the
subject.
Prospects for the Future
When a species is listed as endangered by the
federal government a Recovery Team is usually ap-
pointed, made up of state and federal biologists and
often biologists from universities to develop a
Recovery Plan. The objective of a Recovery Plan is
to provide directions and guidelines for management.
If successful, the abundance of the species will
increase to a point where it is no longer endangered
or threatened and can be removed from the list.
The development of a workable Recovery Plan for
squawfish is not a simple matter. Although such a
plan has been written, the only clearly defined pro-
gram in the plan to increase squawfish abundance is
artificial propagation in hatcheries. The complex
issue of interaction of the squawfish with its physi-
cal and biological environment, and how various
factors may be manipulated to benefit the squawfish,
is included under the title of "development of habi-
tat management plans" in the Recovery Plan. The
problems of developing a workable habitat management
plan and implementing it have not yet been resolved.
Toward this goal, the U.S. Fish and Wildlife Service,
supported by funds from the U.S. Water and Power
Resources Services (formerly Bureau of Reclamation),
has initiated a large-scale study of squawfish and
humpback chubs. This study is designed to obtain the
information needed to develop habitat management plans,
to provide the basis for the planning and operation of
future water development projects in the upper basin,
and to seek ways in which future environmental
modifications might benefit the squawfish. The U.S.
Bureau of Land Management and the Colorado Division
of Wildlife have also been conducting studies and
monitoring programs on the squawfish.
Squawfish can be readily propagated in hatcher-
ies. Hormone injections are necessary to induce
spawning. Young squawfish feed on the same food fed
to trout, and large squawfish feed on fish. Squaw-
fish have been spawned and raised at the Willow Beach
National Hatchery, Arizona. Hatchery propagation,
however, must be considered only as a stopgap mea-
sure in the preservation of squawfish. It is obvious
that the stocking of hatchery reared fish in areas
where the squawfish once occurred but is now gone
will not result in a self-sustaining population
unless the factors causing the elimination of the
squawfish in the first place can be reversed or modi-
fied. Ways must be found to favor successful repro-
duction of squawfish in natural environments. Merely
trying to maintain the status quo by strict protection
of habitat where squawfish still occur will not do
the job of getting the squawfish off the endangered
species list.
Squawfish will play an important role in the
planning and operation of any future dams and water
development projects in the upper basin. Flow and
temperature releases from dams can be planned to favor
squawfish instead of trout. Successful reproduction
might be favored by the creation of artificial areas
where natural nursery sites no longer exist. Methods
of control and replacement of potentially harmful
non-native fishes will probably be necessary in
areas such as the Yampa River, before successful
reproduction of squawfish can be established.
The prognosis is that the squawfish can pro-
bably maintain a healthy and viable population
indefinitely in the Green River below the mouth of
the Yampa as long as the present environmental
conditions are maintained. The probability of
increasing the abundance and distribution into other
areas, where the squawfish has been eliminated or
exists in only small numbers, depends on the suc-
cessful application of creative and holistic thinking
and work.
1982 UPDATE
During recent years a great amount of both field approached. Some squawfish moved up the Green River
work and laboratory studies have been devoted to the into the Yampa River; down the White River, up the
Colorado squawfish. Radio transmitters inserted into Green River, and into the Yampa; from the upper Yampa
the body cavity of large specimens allowed their to the lower Yampa. One squawfish implanted with a
movements to be tracked. Long distance movement was radio transmitter in the upper end of Lake Powell in
found to be common, especially as spawning season 1982, moved about 200 miles up the Colorado River to
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