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

Staging/Resting....................Habitat = Pools or eddies
Depth = 5.5'
Velocity = No restraints
Substrate = No restraints

Deposition/Fertilization....r......Habitat = Riffles or runs
Depth = 5.51
Velocity = 4 fps
Substrate = Gravel, cobble or
boulders

Habitat available for deposition/fertilization at both study sites
and WUA for staging/resting at RK 26.4 (RM 16.5) was optimized at 700
cubic feet/ second (cfs) (Rose 1984). When compared to the historic
flow of record for the Yampa River, 700 cfs is exceeded 98;4% of the
time in June, 75.8% of the time in July, and 13% of the time in August.A
90% habitat retention level was attained for deposition/fertilization at
an approximate range of flows from 350-1100 cfs, and staging/resting
habitat level of 90% retention level for WUA was maintained at approximately
300-1500 cfs. At RK 26.4 (RM 16.5), 90% of optimum WUA occurred based
on mean monthly flows only one time in June, 18 times in July, and 35
times in August f6r 62 years of record.

At the replicate site RM 18.5 (RM 29.6), Rose (1984) calculated 90%
of optimum WUA within a range of approximately 400-1700 cfs. For the
historic period of record, 90% of optimum WUA occurred at RK 29.6 (RM
18.5), one time in June, 36 times in July and 35 times in August. No
staging/resting habitat occurred in the small site studied at RK 29.6.
(RM 18.2).

It is emphasized that the data used (Rose 1984) to develop habitat
utilization curves were collected for Colorado squawfish observed in the
lower 32 km (20 mil of the Yampa River, and relate only to spawning of
Colorado squawfish within the lower Yampa River. They may have little
bearing on other life stage requirements, or other river reaches.

Larvae-Young Colorado Squawfish

Larval Surveys

Weekly larval samples were taken from three reference stations in
the lower Yampa Canyon by seining backwater habitats (Table 7). In
addition, samples were taken in shallow shoreline habitats at the primary
and replicate sites on August 18 and 19. Two Coloradosquawfish larvae
were taken on the repl icate site but none were collected at the primary
site. A total of 104 larval Colorado squawfish were collected in 17
samples, comprising 10% of all fish specimens taken from the Yampa
River.

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