8249

• UCREFRP Catalog Number: 8249
• Author: Modde, T., W. J. Miller and R. Anderson.
• Title: Determination of Habitat Availability, Habitat Use, and Flow Needs of Endangered Fished in the Yampa River Between August and October.
• USFW Year: 1999.
• USFW - Doc Type: Project #CAP-9,
• Copyright Material: NO

Nonnative fIShes

Numerous nonnative fish species have been introduced in the Yampa River basin. Three species are of
particular concern because of possible competition with and predation on endangered fishes include
channel catfish Ictalurus punctatus, northern pike Esox lucius, and smallmouth bass Micropterus
dolomieui. The entire nonnative species component of the fish population was found to be 29%
downstream of Sunbeam (RM 6-64) but 86% near Duffy Tunnel (RM 104.5 - 110.0) (Anderson, in
press). White sucker was found to progressively increase in numbers in an upstream direction and
represented 67% or the fish caught at Duffy Tunnel.

Channel catfish habitat use is life stage specific. Aadland (1993) used habitat preference guilds to define
habitat selection by channel catfish. He assignedage-O channel catfish to the slow-riffle guild (velocity
30-59 cm/s, depth <60 cm), and juvenile and adult catfish to the medium-pool guild (velocity <30 cm/s,
depth 60-149 cm). Although Aadland (1993) assigned juvenile catfish to the medium-pool guild, he
reported that they appeared to be habitat generalists at this lifestage. In the Green and Yampa Rivers,
Colorado and Utah, Tyus and Nikirk (1990) found the highest concentrations of channel catfish in rocky,
high gradient areas. Carlson et al. (1979) collected channel catfish in the Yampa River from a variety of
habitat types and associated velocities; however, these fish were often associated with at least some
boulder size substrate. Results of sampling the Yampa River from July 1975 through October 1977
indicated that channel catfish decreased upstream from Cross Mountain Canyon (Carlson et al. 1979). The
percent composition of channel catfish, for all fish over 15 cm, was estimated to be 6.6% downstream of
Sunbeam (RM 60-64) and 3.9 percent 50 miles upstream near Duffy Tunnel (Anderson, in press).

Channel catfish are generally nocturnal feeders, with peak activity occurring from sunset until midnight
(Sublette et al. 1990). Juvenile channel catfish usually feed on plankton and small aquatic insects. As
adults, channel catfish become omnivorous. Tyus and Nikirk (1990) found aquatic invertebrates, vascular
plants, terrestrial insects, algae, fish, and mice in channel catfish stomachs, although only the largest of
catfish (mean TL=392 mm) had consumed fish. Carlson et al. (1979) found that gut samples from 17
channel catfish collected in the Yampa River near Cross Mountain during September contained only
filamentous algae and diatoms. The optimal temperature for growth of juvenile channel catfish is
between 270 - 290C (Memahon and Terrell 1982); however, growth rates may decrease as a result of
overcrowding or stress caused by low dissolved oxygen levels (Carlander 1969).

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