7056

• UCREFRP Catalog Number: 7056
• Author: Archer, D. L. and H. M. Tyus.
• Title: Yampa River Colorado Squawfish Spawning Study.
• USFW Year: 1984.
• USFW - Doc Type: Salt Lake City, Utah.
• Copyright Material: NO

.... I It

Confusing the issue, "however, is the potential effect of increased
discharge on survival of YOY Colorado squawfish. Warm backwater nursery
habitat was virtually nonexistent in the main channel of the downstream
Green River in 1983, due to the high flow. In 1982, increased discharge
in the Green River was associated with a lowered catch-per-effort of
Colorado squawfish YOY. It is possible that loss of optimum nursery
habitat was responsible for the poor survival of YOY Colorado squawfish
in 1983, or a combination of temperature and discharge.

The necessity for coupling optimum conditions on the Yampa River
spawning grounds with nursery areas in the downstream Green River for
the production of a good year class of YOY Colorado squawfish is becoming
evident, and these needs must be better understood.

CONCLUSIONS

The maintenance of Colorado squawfish spawning in the Yampa River
may be necessary if the Colorado squawfish in. the Green River Basin is
to be preserved in perpetuity. FWS and CDOW (Haynes and Muth 1984) data
show that recruitment in the upper Green River Basin is due to the
production of larvae from the Yampa River and, since the Yampa site
appears largest of the two main sites discovered in the Green River, the
Yampa River recruitment may be the factor driving the whole Green River
Colorado squawfish population. Major factors of concern addressed in
this report in protecting the Colorado squawfish include the provision
of optimum water quality and quantity for spawning, downstream transport
of larvae and rearing of the young in downstream nursery habitats.

Information provided by Rose (1984) and O'Brien (1984) indicate
sufficient flow can be provided for Colorado squawfish spawning habitats.
This information needs to be related to the need for year-round adult
habitat, stream passage (Tyus 1984) and downstream transport of larvae
in the Yampa River. It is just as important, however, to provide suitable
conditions in the Green River below the mouth of the Yampa, since there
is an interdependence between the Green and its free-flowing tributary.
In this respect, Flaming Gorge Dam is a dominating influence and flow
releases from the dam must also be related to the needs of the fish
within the system.

ACKNOWLEDGMENTS

This study was funded in part by the Fish and Wildlife Service and
Bureau of Reclamation. The National Park Service and states of Colorado
and Utah aided in providing logistical support. Thanks are given to the
many State and Federal employees that supported this study in the field,
and special recognition is given to J. J. Krakker who shared supervision
of the field team.

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