9313

• UCREFRP Catalog Number: 9313
• Author: Burdick, B. D., J. Flair, M. Lloyd and B. Scheer.
• Title: Native and Nonnative Fish Use of Two Gravel-Pit Ponds Connected to the Upper Colorado River at 29-5/8 Road Near Grand Junction, Colorado.
• USFW Year: 1997.
• USFW - Doc Type: Project number CAP-6-GP,
• Copyright Material: NO

Seines (1/8-inch ace mesh, 6-foot wide and 30-feet long) were used to
collect post-larval, young-of-the-year fishes in August. Fish that were
identified to species afield were counted and released alive. Total lengths of
a representative sample of fish collected were recorded. No fish were preserved.
The physical parameters recorded for each sample included, 1) length and width
of the seine haul, 2) substrate type, 2 3) and water temperature. Effort was
recorded as area swept by the seine (m ).
Data Compilation and Analysis
Fishery data were recorded on standardized data forms. These data were
then stored in the database management system, DBASE III+, to facilitate access
and analyses as well as to provide data compatible with the computer system
format used by the ISMP database. Computer diskettes containing the
corresponding DBASE III+ files from this study are available upon request through
the ISMP database manager, FWS, Grand Junction, Colorado.
Capture data for sub-adult and adult fish were analyzed by various methods.
Total catch per unit effort (CPUE: total fish collected/total hours sampled
[F/hl) was used to determine relative density of fish in electrofishing, trammel,
and trap-net collections. CPUE was calculated for each fish species and three
sucker hybrids (white sucker X flannelmouth sucker, white sucker X bluehead
sucker, and bluehead sucker X flannelmouth sucker) by pond and sampling period
in 1996. Species composition and relative abundance (expressed as a percentage
of total numbers) were used to describe the fish community by pond and sampling
rotation in 1996. Before a connection channel was excavated between Gardner Pond
and the river, the fish community in the pond was inventoried in the summer of
1995 with electrofishing, trammel and trap nets, and seining to determine
relative abundance and species composition.
Capture data for small-sized fish collected with seines were reported as
total catch per unit effort (CPUE: total fish collected/total area swept by the
seine [F/10m ]). Species composition and relative abundance were also used to
describe the fish community in each pond. Seining was conducted primarily to
assess the annual reproduction of young-of-the-year fish from both ponds.
Length-frequency graphs were plotted for four nonnative fishes collected with
seines to compare the size structure of small-sized fish in both ponds.
RESULTS AND DISCUSSION
Pre-Connection Channel Inventory
During May and August of 1995, the fish community of Gardner Pond was
surveyed to determine the percentage of nonnative fish prior to the pond being
connected to the river. If the fish population was determined to be
predomi nantl y nonnati ve, they woul d have to be removed duri ng the drai ni ng of the
pond and prior to the pond being connected to the river. Of the eleven species
captured nine were nonnatives. Approximately 1,494 fishes were captured with
nonnative fishes comprising 98% of the catch. The nine nonnative fishes
collected in descending order of abundance were black bullhead (42X), green
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