7178

• UCREFRP Catalog Number: 7178
• Author: Miller, W. H., et al.
• Title: Windy-Gap Fishes Study
• USFW Year: 1984.
• USFW - Doc Type: Second Annual Report.
• Copyright Material: NO

Hatchery. The use of these hatchery fish also allowed us to quantitatively
study the survival of age-l-size fish in a natu ral environment. Hatchery
fish were about 3 months old and 50-100 mm long when stocked into the
experimental backwaters of the Colorado River in October 1983. Each
fish was marked with a coded-wire microtag before stocking, as discussed
in the first annual report (Miller et al. 1983).
About 55,000 hatchery-reared Colorado squawfish were stocked into the
Colorado River as part of the river backwater investigations in 1983.
r Fish were stocked at the Walter Walker Wildlife Area, a former gravel-
pit pond that became a large manmade river backwater in early summer
1983 when the flood waters of the Colorado removed much of the dike that
` separated the pond from the river. The distribution and relative
densities of these Colorado squawfish were followed for several weeks
after stocking.
In 1983 five gravel-pit ponds were selected for short-term, quantitative
studies of Colorado squawfish su rvival and a total of 31,000 hatchery
Colorado squawfish were stocked (Table 2). Pond selections were based
largely upon the fish communities that inhabit the ponds. The broad
objective of these studies is to determine the biological and physio-
chemical characteristics of ponds that provide good growth and survival
of age-l-size Colorado squawfish. The multiple census techniques used
in the 1982 pond investigations (Miller et al, 1983) were used to
survey the fish communities of the study ponds before the hatchery-
reared Colorado squawfish were stocked. Each pond will again be stocked.
with hatchery-reared Colorado squawfish in the spring of 1984 and- the
fall of 1984. Survival of each group of Colorado squawfish will be
estimated before the next group is stocked.
In 1983 we redirected apart of our backwater research program. We were
interested in determining when adult Colorado squawfish use backwaters
and whether Colorado squawfish or other rare fishes might use backwaters
for spawning, as well as for resting or feeding areas. An elaborate
two-way fish trap was constructed in the channel between the pond at
Walter Walker Wildlife Area (WWWA) and the adjacent Colorado River. WWWA
in the past had been as a good area to collect adult Colorado squawfish
and razorback sucker, and a seasonal periodicity of use was evident.
9