7315

• UCREFRP Catalog Number: 7315
• Author: Colorado Water Conservation Board.
• Title: State of Colorado Hatchery Feasibility Study for Endangered Fishes of the Colorado River Basin, Vols. 1 & 2.
• USFW Year: 1993.
• USFW - Doc Type: \
• Copyright Material: NO

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REFERENCE NUMBER:

CITATION:

025

Tyus, H.M. 1987. Distribution, reproduction, and habitat use of the
razorback sucker in the Green River, Utah, 1979 - 1986.
Transactions of the American Fisheries Society 116(1):111-116.

SPECIES AND LIFE STAGE:

TOPICS:

KEYWORDS:

SUMMARY:

RZ. RZ_ADU, RZ_LAR

Ute History, Temperature

RAZORBACK SUCKER, LARVAE, TOTAL LENGTII,
SPAWNING, SUBSTRATE, TEMPERATURE, TIMING

Adult razorback suckers were collected from fiat-water sections of the mainstem Green River
and lower portions of the Yampa River. In the Green River the area of highest concentration
was from the mouth of the Duchesne upstream to the mouth of the Yampa River. Six fish
were collected from the lower sections of the Green River also. Total lengths of 323 fish
ranged from 426 - 608 mm TL. Ripe males averaged 503 mm and ripe females averaged 544
nun TI. male to female ratio for all years combined was 1.61:1. Ripe females were
significantly longer and heavier than males. Razorback suckers were more vulnerable to
capture during spawning from May through June.

Razorback sucker larvae were collected downstream of suspected spawning areas. Larvae 10.6 _
13.6 mm TI. were identified by the Larval FISh Lab. of Colorado State Univ. 31% of 42
samples contained 131V3l razorback suckers.

Ripe razorback suckers were collected over coarse sand substrate, but some were collected near
gravel and cobble bars. It is not known whether staging occurs in one area and spawning in
another, or if spawning occurs over both areas. Water temperatures ranged from 10.50 in May
to lSOin June. Average temperatures where ripe fish were captured were 150 for males and 160
for females.

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