9438

• UCREFRP Catalog Number: 9438
• Author: Clarkson, R. W. and M. R. Childs
• Title: Temperature Effects of Hypolimnial-Release Dams on Early Life Stages of Colorado River Basin Big-River Fishes
• USFW Year: 2000
• USFW - Doc Type: Copeia
• Copyright Material: YES

J

CLARKSON AND CHILDS-TEMPERATURE EFFECTS ON FISHES

407

1600 1600 1600
X. texanus X. texanus X. texanus
1200 age = 7 days 1200 age = 14 days 1200 age = 41 days
800 800 800
400 400 400
0 0 0
o 20 40 60 80 100120140 o 20 40 60 80 100120140 o 20 40 60 80 100120140
1600 1600 1600
C. latipinnis C. latipinnis C. latipinnis
1200 age = 7 days 1200 age = 14 days 1200 age = 41 days
800 800 ~ 800 ~
-
0> -~ 400 400
E 400
--
..... 0 0 0
.c
.Ql , , ,
<L> o 20 40 60 80 100120140 0 20 40 60 80 100120140 o 20 40 60 80 100120140
S
1600 1 G. cypha ~ ~~~ 1 G. cypha t600 G. cypha
1200 age = 7 days 80 age = 14 days age = 41 days
80 1200
60 60 t
800
40 ~ 40
20 20 400
0 0 0
o 20 40 60 80 100120140 o 20 40 60 80100120140 o 20 40 60 80 100120140

1600

1200

P. lucius
age = 14 days

800

400

~

o

o 20 40 60 80 100120140

Time (days)

Fig. 2. Changes in weight over time of early life stage big-river fishes reared at three temperatures. Points
represent mean responses of each species; ages are days posthatch at initiation of experiment. Circles denote
10 C, squares 14 C, and triangles 20 C. Note the y-axis scale breaks for age-7 and age-14 Gila cypha.

tant et aI., 1974). Fish drifted in the slow cur-
rent provided from water inflow to the tank un-
til settling to the bottom, where they remained
immobile for approximately 90 min. Over the
next 60 min, they regained their ability to swim

in the water column but appeared lethargic
compared to 20 C control groups. Gila CYPha lar-
vae transferred from 20 C to 12 C became le-
thargic but did not lose their ability to remain
in the water column. No behavioral effects were