7816

• UCREFRP Catalog Number: 7816
• Author: Tyus, H. M.
• Title: Movement and Habitat Use of Young Colorado Squawfish in the Green River, Utah
• USFW Year: 1991
• USFW - Doc Type: Journal of Freshwater Ecology
• Copyright Material: YES

A total of 251 yearling Colorado squawfish was captured in April,
1981. These included 206 new captures (x= 51 mm TL, SO= 11) and 45
recaptures. Five fish marked in backwaters were recaptured in shoreline
runs (Table 1, Figure 2). Highest backwater catches during each 24 h
period usually occurred at mid-day (1100-1500 h, water temperature
170C), and the fish were virtually absent at dawn (0600-0700 h, water
temperature 70C, Figure 3). Average backwater temperatures of 12.40C
were higher than that of the main river channel during the st~dY (9.90C,
range= 8.5-110C), and catch of fish (number of fish seined m- ) was
correlated with backwater temperature (r= 0.91, p= 0.004; Figure 3).
Backwater catches of age-O Colorado squawfish in October, 1981
(n=151, x= 45 mm TL, SO= 7), were highest during similar time periods
and temperature regimes as in the April, 1981, collections (Figure 3).
Backwater temperatures averaged 13.3oC (range 11-17oC),and river

Table 1. Numbers of young Colorado squawfish captured and marked in the
Green River, Ouray National Wildlife Refuge, 1979-1981. B= backwater, E=
eddy, S= shoreline, b= island backwater (see Fig. 2).
Number of marked fish recaptured at each site
Habitat Number1 Number
captured marked 8 E S b
October-November 1979
8 59 49 10
Apri 1 1980
B 578 467 102 3 5
~2 35 31 9 I 1
19 13
Apri 1 1981
B 233 193 39 5
S 18 13 1 I
October 1981
B 111 80 18 3 0 0
b 40 20 3 0 0 1
E 70 56 11 11 0 0
S 0 0
November 1981
82 30 0 6 0 0 0
b 0 0 2 0 0 0
[2 1 0 2 0 0 0
Totals 1,194 922
~Inc1udes all marked and recaptured fish. 1981 were marked in October
Not marked. Fish recaptured in November
1981.
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