6027

• UCREFRP Catalog Number: 6027
• Author: Tyus, H. M., R. L. Jones and L. A. Trinca.
• Title: Green River Rare and Endangered Fish Studies, 1982-85
• USFW Year: 1987.
• USFW - Doc Type: Final Report.
• Copyright Material: NO

Preliminary sampling was conducted during the last week of July to test
equipment. Actual sampling was conducted according to the following schedule:
8/03/82-8/07/82 Nets were set at 6-hour intervals at all five sites
for 48 hours.
8/10/82-8/14/82 Nets were set at 6-hour intervals at all five sites
for 48 hours.
8/17/82-8/19/82 Nets were set at 6-hour intervals at all five sites
for 24 hours.
Larval Colorado squawfish collected from 1981-1985 were used to estimate
time of spawning by back calculation. Date and larval size data were used as
input into a relationship developed by Haynes and Muth (1984) for estimating
time of spawning for Colorado squawfish in the Yampa River. FWS collections
from the Yampa and upper Green rivers (Strata E and F) were lumped to back-
calculate spawning dates for the Yampa River site. Collections from Strata B
and C were lumped to estimate time of spawn in Gray Canyon site (Green River).
DISTRIBUTION AND ABUNDANCE OF POST LARVAL (YOX) COLORADO SQUAWPISH
The Vernal Field Office initiated a special investigation in the late
summer-early fall of 1979 to obtain information about early life history of
Colorado squawfish. This included identification of nursery areas in river
regions occupied by YOY Colorado squawfish of fingerling size (25-60 mm).
Colorado squawfish of fingerling size were sampled with seines from
mid-September through October, 1979 - 1985. These YoY surveys were
quantitative: Colorado squawfish were counted and measured to the nearest mm
(total length), and area seined, water depth and velocity, and substrate siza_
were recorded. Collections were made from RM 363 (RK 581) at the upstream end
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