7780

• UCREFRP Catalog Number: 7780
• Author: Brooks, J. E., et al.
• Title: San Juan River Seven Year Research Program Summary Report 1992.
• USFW Year: 1992.
• USFW - Doc Type: \
• Copyright Material: NO

3. Determine the biological response of fish populations to
the reoperation of Navajo Dam.
4. Determine habitat use and needs of the Colorado
squawfish, razorback sucker, and roundtail chub in the
San Juan River.
5. Characterize water quality in the San Juan River and
identify critical quality issues that may affect recovery
of endangered species..
6. Identify interactions between native and nonnative
fishes.
7. Identify and test management options which could improve
reproduction and recruitment of target species.
RESEARCH PLAN IbIPLEb~PiTATION - The Research Plan consists of an
integrated program designed to evaluate hypotheses related to flow
and habitat conditions in the San Juan. A series of hypotheses
were formulated by research biologists to guide the development of
the Research Plan. Hypotheses that were considered important to
test in the San Juan River included:
Late spring and early summer flows are important for spawning
and recruitment of Colorado squawfish and other native fish
species.
High spring flows affect trout production in the tailwaters of
Navajo Dam.
Seasonally flooded lowlands are important for razorback sucker
spawning.
Populations of endangered fish in the San Juan River Basin are
genetically distinct from other populations in the upper basin
of the Colorado River.
The abundance of native species is related to predation and
competition by non-native species.
Instream barriers affect migration of adult squawfish and
impact drifting larvae of Colorado squawfish and razorback
sucker.
The San Juan River, during certain hydrologic conditions, has
suitable habitat for successful spawning and rearing of
Colorado squawfish, razorback sucker, and other native fish
species.
Native and non-native fish species are affected by water
quality in the San Juan River and its tributaries.
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