7739

• UCREFRP Catalog Number: 7739
• Author: Muth, R. T. and T. P. Nesler.
• Title: Associations Among Flow and Temperature Regimes and Spawning Periods and Abundance of Young of Selected Fishes, Lower Yampa River, Colorado, 1980-1984 - Final Report.
• USFW Year: 1993.
• USFW - Doc Type: \
• Copyright Material: NO

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for Gila sp. and in 1984 for speckled dace, bluehead sucker, and Oannelmouth sucker. Lowest relative
abundance occurred in 1984 for Gila sp., 1982 for speckled dace, and 1981 for bluehead and Oannelmouth
suckers. Relative abundance of age-O fish among nonnative species was highest in 1981 and lowest in 1983
or 1984.

Results of this study suggest species- and group-specific (natives versus nonnatives) relationships
between timing of spawning and fish abundance and flow and temperature regimes. Earlier initiation of
spawning and higher CPUE of age-O fish for aU nonnative~ l'Inillnn~r spawning seasons for red shiner,
"'"'-

sand shiner, and fathead minnow were generally associated with low peak discharge, low-moderate daily
mean and total discharges, and moderate-high numbers of cumulative degree-days. ~versely, Iat~
~ffiiuoD<Jtspawnmg and lower CPUE for aU nonnatives and shorter spawning se!sons for red shiner, sand
shiner, and fathead minnow were generally associated with high peak discharle, moderate-high daily mean
~d total discharles, and low-moderate numbers of cumulative degree-da~ Spawning periods of native
fish species were fairly consistent among years. Associations between flow and temperature and relative
abundance of aU natives, except Gila sp., were opposite of those for nonnatives (associations for Gila sp.
were similar to those for nonnative fishes). Higher CPUE of age-O fish for speckled dace, bluehead sucker,
and Oannelmouth sucker was associated with high discharge and low-moderate numbers of cumulative
degree-days, whereas, higher CPUE for Gila sp. was generally associated with low-moderate discharge and
moderate-high numbers of cumulative degree-days. Conversly, lower CPUE for speckled dace, bluehead
sucker, and Oannelmouth sucker was associated with low-moderate discharge and moderate-high numbers
of cumulative degree-days, whereas, lower CPUE for Gila sp. was generally associated with high discharge
and low-moderate numbers of cumulative degree-days. Overall trends of fISh abundance related to flows
observed in our investigation were very similar to those reported by other authors. Management of flow
~gimes to approximate natural hydrQgraphs and periodically provide above-average magnitudes in _
spring-summer discharges may benefit native fishes and inhibit certain prolific nonnative fIShes.
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