8185

• UCREFRP Catalog Number: 8185
• Author: Valdez, R. A. and B. R. Cowdell.
• Title: Annual Summary Report-1992\
• USFW Year: 1993.
• Copyright Material: NO

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3.1.5 1991 Year Class

A total of 186 age-O Colorado squawfish were captured in this reach in fall 1991, resulting in a catch rate of
2.23/100 m2. By spring 1992 total numbers decreased by 63% to 69, and CPE decreased significantly (Students
't', P>0.05) by 62% to 0.84/100 m2.

Fish captured in spring 1992 averaged 43 mm TL, compared to those captured the previous fall (1991), which
averaged 40 mm TL. This resulted in an average growth of 6 mm from fall to spring.

Three juvenile squawfish, ranging in size from 161 to 169 mm TL, were captured in fall 1991. These fish were
captured together at RM 43.5.

Distribution of age-O Colorado squawfish captured in fall 1991 and spring 1992 are presented in Figure A-II.
Age-O squawfish were more abundant in the lower 50 miles of Reach 3 during fall 1991. The same general
trend was observed in spring 1992 sampling, indicating little or no downstream transport.

3.1.6 1992 Year Class

A total of 119 age-O Colorado squawfish were captured in this reach in fall 1992, resulting in a catch rate of
0.77/100 m2. Average length of these fish was 37 nun TL. Distribution of age-O Colorado squawfish captured
in fall 1992 is presented in Figure A-12. Sampling will be conducted in spring 1993 to complete the
assessment of the 1992 year class.

3.1.7 Svmpatric Species

Age-O Colorado squawfish represented the second or third most common species in backwaters in the lower
Green River in fall and spring (as indicated by mean arithmetic CPE for "primary backwaters") (Figure A-13).
This illustrates that the species is having good reproductive success in this region of the upper basin, but
apparently suffers from poor survival and recruitment to adult stage.

3.2 REACH 4 - THE UPPER GREEN RIVER

Reach 4 on the Green River extends from the Split Mountain Campground (RM 320) in Dinosaur National
Monument to Sand Wash (RM 216). Backwater habitats sampled in this reach from 1987 to 1992 averaged
2.1 ft deep (n = 480). Backwater temperatures during fall sampling were typically 1.70C warmer than the
mainchannel, and 2.90C warmer than the mainchannel during spring sampling.

3.2.1 1989 Year Class

A total of 151 age-O Colorado squawfish were captured in this reach in fall 1990, resulting in a CPE of
1.41/100 m2. This compared to 48 age-O captured in spring 1991 for a CPE of 0.52/100 m2 (Table 5). CPE
between fall 1990 and spring 1991 decreased by 63%, and total numbers decreased by 68%.

3.2.2 1990 Year Class

A total of 62 age-O Colorado squawflSh were captured in this reach in fall 1989, resulting in a CPE of 0.50/100
m2. This compared to 25 age-O captured in spring 1990 for a CPE of 0.55/100 m2. CPE between fall 1989 and
spring 1990 increased by 9%, and total numbers decreased by 60%.