3022

• UCREFRP Catalog Number: 3022
• Author: Berry, C. R. and R. Pimentel
• Title: Swimming Performances of Three Rare Colorado River Fishes
• USFW Year: 1985
• USFW - Doc Type: Transactions of the American Fisheries Society
• Copyright Material: YES

SWIMMING PERFORMANCES OF RARE COLORADO RIVER FISHES 399
VELOCITY (em/second) VELOCITY (em/second)
30 50 70 90 110 130 40 50 60 70
100 LARGE SaUAWFISH .. ... . 100 . . . .
BONYT AIL CHUB
80 4 80
) 60 60
40 40
20 20
0
1.0 2.0 3.0 4.0 3.0 4.0 5.0 6.0 7.0 8.0
VELOCITY (lengths/second) VELOCITY (Ienglhslsecond)
VELOCiTY (em/second) VELOCITY (em/second)
40 50 60 70 80 30 40 50
100 HUMPBACK . . . .. 10 SMALL SaUAWFISH
CHUB iY
80 80
60 ~ 60
'1i
40 40
20 20
.
0 8.0 , 0
3.0 4.0 5.0 6.0 7.0 9.0 2.0 3.0 4.0 5.0 6.0
VELOCITY (lengths/second) VELOCITY (Iengthsfsecond)

FIGURE I. - Relation between percentage oj Jatigued fish and water velocity at 14, 20, and 260C Jor three species
oj rare Colorado River fishes. Points on lines (open symbols) are the moving averages oj three experimental
data points (solid symbols). The 120-min FV50, or velocity at which 50% oJ the fish were fatigued in 120 min,
is shown with 95% confidence intervals. The values on the upper velocity axis are based on the average length
of all fish tested in each group.

1ation (Thompson 1947). Standard deviations and
the t statistic were used to form 95% confidence
intervals.

Results
The 2-min FV50 values for each test group
were slightly larger than the 120-min values (Ta-
ble 1), findings that agree with Brett's (1967) data
for sockeye salmon Oncorhynchus nerka. As ex-
pected, the FV50 values in body 1engths/s for
large Colorado squawfish were lower than those
for small ones, but when expressed in absolute
speeds, the fish-length-speed relation was posi-
tive. The humpback and bonytai1 chubs per-

formed similarly and had higher FV50 values
than Colorado squawfish of about the same size.
Analysis of variance showed that water veloc-
ity significantly affected the mean fatigue time
for all species (P < 0.01), Fish-length ranges cov-
ered 116 mm for large Colorado squawfish and
only 17-60 mm for other groups, but these dif-
ferences had no significant effect on fatigue time
(P > 0.01).
Temperature significantly affected the perfor-
mance of small fish (analysis of covariance, P <
0.01), but not of large fish. Increasing tempera-
tures usually reveal some optimum at which the
swimming ability of fish is maximum (Brett et