9314 ‎(2)‎

• UCREFRP Catalog Number: 9314
• Author: Wick, E. J. and J. A. Hawkins.
• Title: Colorado Squawfish Winter Habitat Study.
• USFW Year: 1989.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

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the fall and relocated apparently recovered from any disorienting effects and
were subsequently monitored through each winter.
After ice formation, in late November and early December, fish stayed
within very specific river reaches (home sites or overwintering areas). Fish
did not move outside of their overwintering areas until ice-out. In addition,
fish used very specific areas within a given habitat. They often stayed in
these areas th:rot? the winter or repeatedly returned to them after using
other areas for a short time. This suggests homing and fidelity to very
specific overwintering habitats. During the period of ice cover, movement
averaged 0.3 mile each year with ranges of 0.0 - 1.1 miles in Winter 1 and 0.0
- 0.5 mile in Winter 2 (Table 5). The three fish that used the backwater at
RMI 95.7 consistently utilized that habitat on every monitoring trip in Winter
1, and one fish (A10) used it both winters. In Winter 1, five fish used the
embayment at RMI 81.1 in conjunction with main-channel habitats; only B09 used
it each trip. The other four fish (A09, BOB, B10, and B11) used the embayment
with occasional forays into the main-channel pool and run area at RMI 81.4.
Fish B11 returned and used this embayment in the fall and winter during the
second year of the study. Fish in the Lily Park area tended to remain within
a given pool throughout the winter, but there was some movement between pools
within the river reach. All other fish were found in main channel habitats
such as eddy, run, or shoreline; these fish tended to move the greatest
distance during the winter. During Winter 2, A91, A70, and C91 could not be
located during the winter period but were found after ice off.
Ice break-up (ice-off) occurred on March 7-9, 1987 and March 19-22, 1988.
Radiotagged fish were located downstream of over-wintering areas within a week
after ice-off both years, except the four fish (BOB, B09, B11, and A09) that
were within the embayment at RMI 81.1 in Winter 1. In Winter 1, all fish in
the backwater (RMI 95.7) moved out during ice-off. This would be expected
since the backwater was dramatically changed by the hydrologic events of ice-
off and the resulting scouring and flooding of the dislodged ice and water.
Downstream movement of 17 fish averaged 0.8 miles for both years. One other
fish (BB7) was located 7.4 miles upstream after ice-off. It is likely that
this fish did the majority or all of this movement after the ice-off event.
Eight transmitters in fish from the first year were operable during the
fall of 1987. All eight of these fish were located within the same study site
in which they were tagged during fall 1986. Three additional fish were tagged
during 1987 in the Lily Park Study area for fall monitoring. Average movement
of these eleven fish during the fall from September 21 through November 20,
1987 averaged 0.9 mile and ranged from 0.0 to 4.4 miles. six fish moved
between 0.1 and 0.7 mile and three showed no change in river mile location
during the fall (Table 5).
Movement during non-spawning times was greatest in the spring, averaging
6.5 miles (range 0.0 - 43.2 miles) in spring 1988 with most fish moving in a
downstream direction. No data were collected in spring 1987. Fish A00 moved
43.2 miles in April 1988 (24.6 miles occurred in a 2-day period frCM April 19
to April 21). The next farthest moving fish moved only 8.5 miles. If A00 is
not considered in the calculation, the average spring movement was 2.9 miles
for the remaining 10 fish. Two fish (C00 and C87), in addition to moving
down.stream, moved up into the Little Snake River, 1 and 6.7 miles
respectively, in May and June. These movements were probably in response to
increased flows which altered habitats that had been suitable in the winter.
Fish probably moved to habitats more suitable for high water conditions.
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