9439

• UCREFRP Catalog Number: 9439
• Author: Upper Colorado River Endangered Fish Recovery Program.
• Title: Nonnative Fish Control Workshop
• USFW Year: 2002.
• USFW - Doc Type: Summary, Conclusions, and Recommendations.
• Copyright Material: NO

The study recommended the following:
1. determine if nonnative fish control activities reduce the numbers of nonnative fish
entering the rivers possibly through the use of stable isotopes or GIS;
2. evaluate the effectiveness of inlet/outlet screens in controlling the movement of
nonnative fish out of riverside ponds;
3. investigate the possible impact of recently developed wetlands as chronic sources
of nonnative fish entering the Colorado and Gunnison rivers;
4. encourage additional enforcement of the nonnative fish stocking regulation in
Colorado;
5. determine the impact of stocking nonnative fish above 6,500 feet elevation on the
abundance of nonnative fish in the Colorado River below Rifle and in the
Gunnison River below Austin and consider a reporting requirement for fish
stocked above 6,500 feet in these drainages;
6. conduct a literature review of potential/optimal screen designs with consideration
of the current nonnative fish composition in both ponds and rivers, site
constraints, fouling/maintenance impacts, dam safety and cost; and
7. examine the potential of installing a series of horizontal flat plate screens in the
bottom of large irrigation drainage ditches to remove juvenile/adult nonnative fish
from return flows to the Colorado River.
,. 3.3.2 Evaluation of Nonnative Stocking Regulations (Project No. 106; CDOW)
' The State of Colorado is currently evaluating State stocking regulations and policy in light of the
Stocking Procedures developed by the UCRRP in 1996 (see section 2.4). State regulations
currently require screening outflows and in some cases inflows/inlets of individual ponds, below
' 6,500 feet elevation within the Upper Colorado River Basin, to minimize escapement of
nonnative fishes from stocked ponds, into occupied and critical habitat of the four endangered
fishes. Data from stocking permits, private aquaculture records and baseline inventory are being
' used in a GIS-based analysis to examine links between stocking of off-channel ponds and the
presence/abundance of the same species in the mainstem Colorado River. This analysis will
provide background for a risk assessment for stocking nonnative fish species. Efforts such as
' described in section 3.2.1 of this document illustrate the difficulty of enforcing a stocking
regulation broadly to all ponds and the complexity of overseeing and enforcing required
screen placements.
' 3.3.3 Operation and Management of Large Wetland Depressions on the OuraY National
' Wildlife Refuge (Project No. CAP-6 OCW; USFWS-Vernal)
The Recovery Implementation Program for the Endangered Fishes in the Upper Colorado River
Basin (Recovery Program) began investigating off-channel wetlands as habitat for endangered
' fishes between 1994 and 1996 at Old Charlie Wash on the Ouray National Wildlife Refuge. Old
Charlie Wash is a natural depression in which natural levees were expanded and a water drain
' was added. Following the 1994 field season, the water control structure of the wetland was
rebuilt to improve draining and a second water control structure and concrete footings were
added to permit a census of fish in the impoundment. During the initial studies between 1994
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