7823

• UCREFRP Catalog Number: 7823
• Author: Miller, W. H., et al.
• Title: Colorado River Fishery Project, Part II, Final Report, Field Investigations.
• USFW Year: 1982.
• USFW - Doc Type: \
• Copyright Material: NO

River stage was an important factor in determining sampling effi-
ciency. Field teams had little success in collecting fish during early
prerunoff with all gear types, especially with passive gear. Because
passive entangling nets (gill and trammel) rely upon fish to be active
and moving, it was reasonable to attribute the low catch rates to cold
water temperatures, which cause fishes to be inactive. Electrofishing
and seining (active gear) were most successful during prerunoff.
Effectiveness in catching fish during runoff was complicated by high,
turbulent water conditions. Seining during runoff was difficult and
sometimes impossible. Trammel and gill nets during runoff were exclu-
sively used in eddies with only limited success.
Habitat preferences of all fish species
This section presents data obtained from the enumeration of fishes
collected in five habitat types. Habitat preference is inferred from
conditions measured at point of capture. Extreme caution should be used
when interpreting the information presented on number of fishes collected
for the various habitats since these data represent the total number of
fishes collected in a given habitat type using all gear types. These
habitat types are not uniformly represented in all strata. However, all
habitat types within an intensive reach were sampled using at least one
gear type. More complete analysis of these data will be made later,.
using a number of variables including stratum, habitat type, water depth,
water velocity, and substrate type.
Backwaters generally contained more fish than any other habitat,
primarily the small species of minnows (e.g., red shiner and fathead
minnow) and young and juveniles of the larger species (e.g., Colorado
squawfish and flannelmouth sucker). Adults of species other than the
small cyprinids were uncommon. YOY Colorado squaw€ish and fathead
minnows showed a high preference for this type of habitat. Red shiners
coexisted with young Colorado squawfish but were ubiquitious in all other
five habitats sampled.
Eddies frequently contained the greatest number of adults of the
larger species, and occasionally contained large numbers of young red
shiners, carp, roundtail chubs, and channel catfish. Black bullheads
were also found in eddies.
Collections made in shoreline habitat also contained high numbers of
the larger species as well as red shiners. Adult bluehead suckers,
flannelmouth suckers, Colorado squawfish, and Gila spp. were collected
from this habitat type in most strata.
Flannelmouth suckers and red shiners were more numerous than other
species in runs. However, this reflects general abundance through
several habitats rather than a preference for runs, since run is a
relative descriptor. Channel catfish were also common in runs.
Riffles are limited in the Green River, occurring most frequently in
strata C and D. No riffle habitat was sampled in strata E and F. The
40 only species collected from riffles were red shiners, Gila spp., speckled
dace, flannelmouth suckers, and bluehead suckers. The latter three were
the most common species collected.
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