WSP06389

• File Number: 8220.102.01.I
• Description: Aspinall ‎(AKA Curecanti)‎
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 1/1/1994
• Title: Scopes of Work - Endangered Fish Program as Related to Aspinall
• Water Supply Pro - Doc Type: Report/Study

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reproduction and recruitment of humpback chub in Westwater Canyon and the
impact of re-regulating the Aspinal Unit. Spawning and nursery
requirements, larval drift, recruitment, and reproductive isolating
mechanisms of humpback chub in Westwater Canyon will be examined as they
are affected by flows and the operation of the Aspinal Unit. The study
will employ radiotelemetry as a means of identifying spawning sites.
Drift net stations will be established to assess the extent of larval
drift, and low-velocity areas will be seined to identify age-O nursery
habitat. Spawning sites and nursery areas will be mapped and described as
these are affected by various flow levels. Successive year classes will
be monitored to identify the river conditions that maximize recruitment to
the adult portion of the population. Also. the invasion and proliferation
of non-native species into Westwater Canyon will be assessed by analyzing
catch-per-effort statistics of the ISMP Humpback Chub Monitoring Program
and past CRFP collections, and compare these with catch rates of this
study. The study will also examine the possibility of reproductive
overlap with roundtail chub invading the areas.

VI. Task Description (FY-1994): See attachment

Task 1. Westwater Canyon will be seined on a regular basis through summer
and fall to follow the strength of the cohort as well as length of
individuals. Low velocity areas will be seined and the fish sorted,
released and identified when possible. Specimens that are difficult to
identify will be sent to LFL.

Task 2. Data from 1979-81 (Valdez et al. 1982) and 1986-91 (Moretti and
Chart 1991) will be assimilated together with hydrologic flow and
temperature records from the Stateline USGS Gage. The catch rates and
species composition of these data will be compared with data collected by
this study. Catch rates of non-native species will be related to flows
and temperature regimes to identify flow and temperature scenarios
conducive to their invasion and proliferation. Past catch rates of
roundtail chub will also be compared with flows and temperature to assess
the possibility of hybrization with humpback chub.

Task 3. This investigation will incorporate the information collected by
the ISMP Humpback Chub Monitoring Program. Data collected from that
program will be analyzed to assess the occurrence of sympatric species in
Westwater Canyon. These data will be compared to river flow regimes such
as spring peaks, duration, timing, and temperature to determine if certain
flows reduce the invasion of non-natives into these regions.

Task 4. Each of the five cohorts hatched during this investigation (1992-
1996) will be monitored yearly to assess recruitment and relate it to
river hydrology and temperature. The survival of age-O through age-2 fish
will be determined through catch rates from seine information. The
survival of age-3 fish and older will be determined from catch rates in
gill nets and from mark and recapture information (fish longer than 150 mm
TL will be PIT tagged) .

Task 5. MUch can be learned by examining past collections and data. Data
collected by past investigators will be synthesized with current
information and compared with the river hydrology. Recruitment will be
assessed by examining year class strength and relating it to river flows
for the given year.

Task 6. Utah State University researchers will work with UDWR crews and
principal investigator to evaluate the geomorphic basis of nursery
habitats and describe the physical processes that maintain them.

VII. Study Schedule (start/end by task): This proposed investigation will be
conducted primarily during the months of March through October for a