7090

• UCREFRP Catalog Number: 7090
• Author: Archer, D. L., L. R. Kaeding and H. M. Tyus.
• Title: Colorado River Fishes Monitoring Project Final Report.
• USFW Year: 1986.
• USFW - Doc Type: Lakewood, Colorado.
• Copyright Material: NO

Humpback chub

Adult (200+ mm TL)
Spawning
Larvae-juvenile (8-199 mm TL)

Razorback Sucker

Adult (450+mm TL)
Spawning

The adult Colorado squawfish classification generally pertaines to fish
capable of spawning but this classification included all Colorado
squawfish greater than 449 mm due to the difficulty of determining
sexual maturity and the fact that males mature at a smaller size and
younger age (Seethaler 1978).

The Colorado squawfish spawning period classification was based upon
observations of radiotelemetered fish larger than 449 mm that migrated
to suspected spawning areas and captures of ripe adult fish in those

areas.

The larval classification defines the life-stage from hatching to about
30 mm which are not large enough to be captured with a 3-5 mm mesh
seine, the seine size adopted for sampling of post-larval young-of-the-
year Colorado squawfish during fall sampling and which can be macrosco-
pically identifiable in the field.

The YOY, post-larva classification includes the 30-60 mm size range
which can be effectively captured with the standard 3-5 mm seine and are
identifiable in the field. This size group has also been observed to
occupy a specific habitat type called ephemeral backwaters during a
major portion of the year.

The juvenile classification primarUy includes that size range (60-
449111D) beyond the first year until reproductive maturity is possible.

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