7729

• UCREFRP Catalog Number: 7729
• Author: Valdez, R. A., W. J. Masslich and A. Wasowicz.
• Title: Annual Summary Report - 1990\
• USFW Year: 1991.
• Copyright Material: NO

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Subreach ill: Salt Creek (RM 41.3) to Dolores-San Miguel River Confluence (RM 64.4)
(Corresponds to USFWS Stratum V)

Subreach IV: Dolores-San Miguel River Confluence (RM 64.4) to Paradox Valley at Bedrock (RM
74.8) (Corresponds to USFWS Stratum W)

Subreach V: Paradox Valley at Bedrock (RM 74.8) to Slickrock (RM 124.7) (No corresponding
lJSFWS Stratum)

3.0 METHODS

3.1 Sampling Trips

Three sampling trips were conducted during 1990, each consisting of approximately 10 days in the
field (Table 1). Field trips were scheduled so that sampling would be conducted on a seasonal basis,
including a pre-runoff late winter/early spring sample (March), a post-runoff summer sample (July)
and a fall sample (October).

3.2 Sampling Effort and Techniques

A summary of the sampling effort by trip for each gear type is presented in Table 2. An effort was
made to expend similar sampling effort during each of the three trips. Increased familiarity with the
study area allowed for increased sample effort with each successive trip. Time used to conduct
reconnaissance and general habitat surveys also decreased over the three trips, which allowed
additional time for sampling.

Standard gear and techniques were used to sample fish in the Dolores River. The three principle
sampling techniques were seining, electrofishing and netting with gill and trammel nets. Some gear
types proved more effective in certain areas, due to a wide range of flows and channel characteristics.

Seining represented the most consistent fish sampling technique used in each subreach of the study
area. Although sampling effort was not always consistent between trips or subreaches, factors
affecting seining catch rates were not as variable as with other sampling techniques. Seining was used
to collect fish in all habitat types within the study area with the exception of deep pools and runs.
Seining was most effective for sampling the early age-classes of the larger fish as well as a range of
the smaller-sized species. Information documented with each seining effort included: sample size
(length and width), maximum depth of sample, primary and secondary substrates, primary and
secondary habitats.

Gill and trammel nets were generally effective throughout the Dolores River although use of the gear
was more conducive to certain river reaches with a deeper channel and greater flow. Gill and
trammel netting was used primarily to sample larger age classes and species of fish in deeper habitat
such as pools, runs and eddies. Information documented for each netting effort included the
following: location, temperature, primary and secondary habitat, and duration of net set. Factors that
affected the efficiency of gill and trammel netting included river flow, channel morphology, floating
debris, and excessive turbidity. Netting was ineffective for sampling shallow habitats or for sampling
during periods of high debris flows.

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