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

These samples indicated that spawning occurred in the Yampa River prior
to August 10. Larvae were most abundant in our samples in the lower
Yampa River between August 19-30, 1983. The Colorado Division of Wildlife
(Haynes and Muth 1984) also sampled for Colorado squawfish larvae in
1983 and found the peak abundance for drifting larvae occurred from July
28 - August 6. They estimated the recruitment from 1983 year class was
far greater than the 1980-82 classes.

Table 7. Colorado squawfish larval collections, Yampa River 1983a

Location
Date km mi No. Larvae
8-04 2.6 1.6 0
8-04 0 0 0
8-10 2.6 1.6 5
8-10 0 0 2
8-10 3.0 1.9 7
8-18 29.1 18.2 2
8-19 26.2 16.4 0
8-19 3.0 1.9 10
8-19 2.6 1.6 23
8-23 3.0 1.9 27
8-23 2.6 1.6 2
8-30 3.0 1.9 0
8-30 2.6 1.6 26
9-12 3.0 1.9 0
9-12 2.6 1.6 0
aLarvae identified by CSU Larval Fish Lab.

Size Range (mm TL)

9.1 - 10.6
9.9, 10.3
8.8 - 10.0
la.5, 10.9
10.6 - 13.8
10.7 - 12.6
11.8 - 17.0
13.1,14.0
10.5 - 17.8

Larval Colorado squawfish are probably transported downstream as
soon as they hatch. This downstream transport or drift also appears to
occur along the shoreline, since they are quite vulnerable to capture
with shoreline larval seines, but difficult to capture with midchannel
ichthyoplankton traps (Miller et al. 1983). This behavior would enable
the larvae to take advantage of wanner, quieter water along the shore,
and also to select suitable nursery areas for feeding. Haynes and ~~uth
(1984) found that drift'-captured Colorado squawfish larvae were predominately
protolarvae (young), but seined larvae were metalarvae (older) and were
more capable of habitat selection.

27