WSP00586

• File Number: 8240.300.02
• Description: San Juan River Recovery Implementation Program - Recovery Plans & Information
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 1/1/1999
• Title: San Juan River - Recovery Implementation Program ‎(RIP)‎ -- Executive Summaries - 1999 to Present
• Water Supply Pro - Doc Type: Report/Study

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EXECUTIVE SUMMARY

As part of the San Juan River Basin Recovery Implementation Program (SJRlP), investigations
of non-native fishes were conducted during 1991-1997 to characterize interactions with native
fishes. The impacts of non-native fish species on natives has often been identified as a key
impact, along with habitat alteration, that facilitates loss of native biological diversity. In the San
Juan River, the endangered Colorado pikeminnow Ptychocheilus lucius and razorback sucker
Xyrauchen texanus, as well as the other members of the native fish community, are the focus of
the SJRIP. A major component of native fish recovery efforts in the San Juan River is the
mimicry ofthe natural hydro graph, and SJRIP studies were designed to assess the response of the
resident fish community to variable flow conditions affected the releases from upstream Navajo
Dam. Section 5.4 of the SJRIP Long Range Plan identified several informational and action
needs regarding non-native fish species: 1) characterize distribution and abundance patters of
non-native fishes, 2) characterize habitats used by non-native fishes, 3) describe the food habits
of non-native fishes, 4) characterize the response of non~native fishes to varying flow regimes, 5)
develop a non-native fish stocking policy, 6) develop regulations to restrict bait-fish species
harvest, 7) develop regulations to control importation of non-native fishes, and 8) monitor and
evaluate non-native fishes control actions implemented as part of the SJRIP. This report presents
results of non-native fishes investigations that address items 1-4 and 8 above.

The distribution and abundance patterns oflarge-bodied nou-native fishes were studied to
determine responses to varying flow regimes. Sampling was primarily by raft-mounted
electrofishing, but also included limited hoop and trammel netting. Main and secondary channel
sampling collected 18 species of non-native fish. Channel catfish Ictalurus punctatus and
common carp Cyprinus carpio were the most abundant and the most widely distributed species.
Seasonal movements of striped bass Marone saxatilis and walleye Slizostedion vitreum out of
Lake Powell and upstream into the San Juan River as far as Shiprock, New Mexico were
documented. Mark and recapture studies of channel catfish and common carp were used to
estimate abundance and to evaluate movement patterns for the entire reach of the San Juan River
sampled, Farmington, New Mexico downstream to Clay Hills, Utah. Schnabel population
estimates (95% C.r.) for channel catfish ranged from 131,768 (72,143 - 219,393) in 1992 to
274,484 (115,712 - 563,162) in 1995 and for common carp were 26,576 (14,213 - 45,019) in
1992 to 107,268 (61,438 - 172,692) in 1995. The proportional abundance of non-native species
sampled during electrofishing surveys in main and secondary channel habitats increased during
1994-1997, after initial declines observed duringI991-1994. Implementation of high spring
releases from Navajo Dam did not appear to negatively impact non-native species distribution or
abundance.

Recapture rates for 3,878 channel catfish and 3,034 common carp tagged with numbered Floy
tags were 5.8% and 10.8%, respectively. Neith~r species exhibited strong movement patterns to
or affinities for specific areas of the San Juan River as has been documented in other river
systems. The mean distance moved between recapture and original or last capture locations was

San Juan River Non-native Species Interactions, Final Report, 1 February 2000

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