9522

• UCREFRP Catalog Number: 9522
• Author: U.S. Fish and Wildlife Service.
• Title: Life History of the Colorado Squawfish in the vicinity of Tusher Rapid.
• USFW Year: 1984.
• USFW - Doc Type: Vernal.
• Copyright Material: NO

nursery habitat that forms
a temporal adaptation fits
squawfish since the length
reduced. This strategy is
young to feed is ba]anced
maximize growth.
during this period in the Green River. Such
in we]1 with the life strategy of the Colorado
of exposure of its young to predators is
apparently successful if the reduced time for
~y delivering them into ideal conditions that
Colorado squawfish select highly oxygenated whitewater rapids and
riffles for spawning sites that may be 100 Kilometers (km) or more from
their preferred adult habitat (Archer and Tyus 1984). Although the
mechanism by which these fish congregate in spawning areas is unknown, a
homing response (Tyus 1985) apparently results in a sufficient number of
breeding adu]ts returning to a small area to insure good genetic recom-
bination and, therefore, maintain a high degree of genetic diversity in
the population. To date only two spawning sites have been confirmed
for Colorado squawfish in the entire Colorado River system and these are
in the Green River basin. Other areas are also suspected in the Green,~~.~
and~le 1). Areas of particular concern in this report are the
confirmed Gray Canyon site near Three Fords Rapid, (RM 156) and a
suspected site at Tusher Rapid, (RM 124)