9688

• UCREFRP Catalog Number: 9688
• Author: Upper Colorado River Endangered Fish Recovery Program.
• Title: Nonnative Fish Control Workshop Summary, Conclusions, and Recommendations.
• USFW Year: 2002.
• USFW - Doc Type: Lakewood, CO.
• Copyright Material: NO

2.2 Nonnative Fish .Issue Paper
On September 30, 1991, an issue paper by Hawkins and Nesler (1991) consolidated and.
described for the first time in detail many of the effects of nonnative fishes on the endangered
fishes. Problematic species were identified and pertinent research was cited linking particular
nonnative fish species to effects from competition and predation. The report provided guidance
for study and management of impacts of nonnative fishes through literature review and expert
opinion. The report concluded that:
• nonnative fish competition and predation problems occur in most upper basin
drainages;
• nonnative fishes of greatest concern include: channel catfish, red shiner, northern
pike, common carp, green sunfish, and fathead minnow;
• young Colorado pikeminnow and razorback sucker, as well as young of many
native fishes are negatively affected by nonnative fishes, but research is needed to
identify mechanisms and management actions to minimize these.impacts;
• except for northern pike in the Yampa River and channel catfish in many parts of
the upper basin, riverine sport fisheries for other nonnative fishes have small or
inconsequential impacts on native fishes;
• incidental take of endangered fishes by angling is not a significant problem; and
• elimination, reduction, or regulation of stocking most common nonnative fishes is
proposed.
2.3 Selective Control of Nonnative Fishes
In June 1996, Lentsch et al. (1996) assimilated a report on nonnative fish interactions and
potential selective control methods. The report recommended options for controlling
problematic nonnative fishes using information on species abundance, distribution, and life-
history requirements. Four categories of control methods-were identified: (1) chemical, (2)
mechanical, (3) biological, and (4) physicochemical. Different control methods were identified
as most effective for different groups of fishes. Physicochemical approaches were the most
promising option for most cyprinids (minnows) and catostomids (suckers). Mechanical removal.
was the most promising method for ictalurids, including channel catf sh-and black bullhead.
Control of northern pike was recommended through increased angling pressure, establishment of
barriers to prevent escapement from source reservoirs, and netting and electrofishing
concentrations of fish in floodplain habitats. Control of centrarchids, especially largemouth bass
and green sunfish, was recommended by first reducing escapement from impoundments and then
targeting spawning aggregations with mechanical and/or chemical treatments.
2.4 Nonnative Fish Stocking Procedures
Procedures for Stocking Nonnative Fish Species in the Upper Colorado River Basin (Stocking
Procedures; U.S. Fish and Wildlife Service 1996) was developed as a guidance document to
ensure that stocking of nonnative fishes in the upper basin was consistent with recovery of the
four endangered fishes. A Memorandum of Agreement was signed on September 5, 1996, by the
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