7048

• UCREFRP Catalog Number: 7048
• Author: Desert Fishes Council ‎(Edwin Pister, e.
• Title: Proceedings of the Desert Fishes Council
• USFW Year: 1991.
• USFW - Doc Type: Volumes XX and XXI
• Copyright Material: NO

Methods
Specimens of R. osculus thermalis were collected from Kendall Warm
Springs and R. oo. varrowi from three sources: the Green River upstream from
the mouth of Kendall Warm Springs, : Boulder Creek, a tributary downstream
from its mouth, and Duck Creek, a tributary to the Green River near
Pinedale, Wyoming. Collections were made in accordance with permits issued
by the U. S. Fish and Wildlife Service (FA/SE/Blanket Permit, Subpermit 86-
16) and the Wyoming Game and Fish Department (Permit No. 91). Collection
dates were October 3, 1987 and September 6, 1988 in Kendall Warm Springs and
Duck Creek, and September 7, 1988 in the Green River and Boulder Creek.
Dace were taken with dip nets in Kendall Warm Springs and with a backpack
electrofisher in the other waters. A total of about 50 dace from each
source were preserved in formalin for morphologic measurements. About 150
from Kendall Warm Springs, 75 each in 1987 and 1988, and about 350 from Duck
Creek, 250 in 19877 and 100 in 1988, were transported live to Montana State
University in Bozeman. All references to live specimens of speckled dace
(R_ o. varrowi) in this report refer to those taken from Duck Creek.
Morphologic and meristic measurements followed standard procedures and
concentrated on numbers of fin rays, lateral line scales, and pharyngeal
teeth.
For tests on thermal tolerances, Kendall Warm Springs dace and
speckled dace were acclimated to 27 C. and speckled dace also to 24 C.
before,being subjected to standard measurements (Paladino et al. 1980) of
their critical thermal maxima (CTM). Dace were tested individually in 14.5
liter tanks. Temperature started at the acclimation level and was raised at
a rate of .45 C per minute until the endpoint was reached of first loss of
equilibrium by the fish.
Electrophoretic analyses of protein variation and mitochondrial DNA
were conducted both on specimens sacrificed from among those maintained
live, and specimens frozen after dying in captivity. Protein variation of
both liver and muscle tissue was studied through methods similar to that
described in Brussard et al. (1981), while techniques for comparisons of
mitochondrial DNA (mtONA) restriction endonuclease cleavage sites were
similar to that described by Avise et al. (1984).
For attempts at captive breeding, speckled dace were maintained at
temperatures of 15 to 24 C. and Kendall Warm Springs dace at 24 and 28 C.
under 14 hour photoperiod, until specimens appeared to become gravid.
Specimens tentatively identified to sex by external appearance were placed
in 75-liter spawning tanks in groups of three, two males and a female, or
five, three males and three females. Spawning substrates were either
gravel, small rocks, or a contoured, woven, plastic material (Tensar Mat,
Tensar Corporation, Morrow, Georgia) held down with rocks and gravel.
Results and Discussion
Morphology
Selected morphological features are presented in Table 1. The number
of lateral line scales is significantly lower in Kendall Warm springs dace
than in speckled dace from the other three sources, and the number of
pectoral fin rays is significantly different from those of speckled dace
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