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

Natural Adaptations and Controlled Systems
P, Lucius evolved as a species adapted to conditions existing at the close
: '~ of the Cenozoic era. These same adaptations enabled it to compete and survive
in the isolated and depauperate Colorado River Sasin in the Recent era until
the coming of man. It is generally agreed that water development negatively
affects the fish (Ono et a1.~1983) and in all areas of the Colorado River
where a significant habitat change or blockage of stream passage has .occurred
(Figure 6) the fish has disappeared (Figure 7). Paramount in the life
strategy of the Colorado squawfish is the need for unimpeded movement within
the riverine system and the extirpation of the fish from areas where blockage
of major stream sections occurs is a testimony to this fact. For this reason,
stream passage cannot be blocked without the possibility of serious impacts to
the species. Also, the downstream transport of larvae and establishment of
shallow ephemeral embayments for nursery areas dictate that a proper discharge
regime be maintained, especially-for spawning and rearing of young.