8236

• UCREFRP Catalog Number: 8236
• Author: Douglas, M. E. and P. C. Marsh
• Title: Population and Survival Estimates of Catostomus latipinnis in Northern Grand Canyon, with Distribution and Abundance of Hybrids with Xyrauchen texanus
• USFW Year: 1998
• USFW - Doc Type: Copeia
• Copyright Material: YES

COPEIA, 1998, NO.4

918
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Trips

Fig. 1. Cormack:Jolly-Seber population estimates
(adjusted for effort) for adult (> 150 mm TL) Catos-
tomus latipinnis by sampling trip in the Little Colorado
River (Navajo Nation, Coconino County, AZ). Trip 49
not plotted due to close of project. Vertical lines
bracket March-April-May (i.e., spring) of 1992, 1993,
1994, and 1995.

TABLE 1. INDIVIDUAL Catostomus latipinnis GROUPED
BY SEASON. Winter = December, January, February;
spring = March, April, May; summer = June, July,
August; and autumn = September, October, and No-
vember. Year refers to year-of-capture.

Number Season/year C. latipinnis
01 Summer 1991 236
02 Autumn 1991 166
03 Winter 1991 65
Total 1991 467
04 Spring 1992 75
05 Summer 1992 125
06 Autumn 1992 171
07 Winter 1992 1
Total 1992 372
08 Spring 1993 131
09 Summer 1993 250
10 Autumn 1993 73
11 Winter 1993 139
Total 1993 593
12 Spring 1994 255
13 Summer 1994 323
14 Autumn 1994 218
15 Winter 1994 102
Total 1994 898
16 Spring 1995 248
Total 1995 248
Total 2578

TABLE 2. INDIVIDUAL Catostomus latipinnis GROUPED
FROM RESPECTIVE CAPTURE-HISTORY MATRICES BY SIZE
CLASS.

Size class Total length C. latipinnis "
1 150-200 258
2 201-250 271
3 251-300 251
4 301-350 184
5 351-400 345
6 401-450 417
7 451-500 403
8 501-550 314
9 551-600+ 135
Total 2578

mates over four seasons revealed two of six com-
parisons were significant; summer versus au-
tumn (F = 4.41; P < 0.04) and autumn versus
spring (F = 4.86; P < 0.03). However, there
were no significant differences among years
with regard to overall population size.

Survival probabilities.-During 1991-1993, surviv-
al rates for G. latiPinnis were relatively uniform
over size classes 1-4 (Fig. 3). Steep decreases
occurred in size classes 2 (201-250 mm TL) and
4 (301-350 mm TL), whereas a steep increase
was noted in size-class 3 (251-300 mm TL). A
generally positive trend occurred from size-
classes 5 through 9 (351-600+ mm TL). How-
ever, survival in 1994 was lowest of the study for
size-classes 4 and 6-8.

Xyrauchen texanus/Catostomus latipinnis hybrids.-
Forty-one X. texanus/G. latiPinnis hybrids were

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Seasons

Fig. 2. Cormack:Jolly-Seber population estimates
(adjusted for effort) for adult (> 150 mm TL) Catos-
tomus latipinnis by season (n = 1-16) in the Little Col-
orado River (Navajo Nation, Coconino County, AZ).
Vertical lines in graph represent spring of 1992,1993,
1994, and 1995.