7311

• UCREFRP Catalog Number: 7311
• Author: McCarthy, M. S. and W. L. Minckley
• Title: Age Estimation for Razorback Sucker ‎(Pisces
• USFW Year: 1987
• USFW - Doc Type: Catostomidae)‎ from Lake Mohave, Arizona and Nevada
• Copyright Material: YES

ISSUE 2, 1987 AGE ESTIMATION FOR RAZORBACK SUCKER 93
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LOG1D SAGITTA RADIUS
Figure 5. Linear regression of loglo-transformed data of
sagitta radius versus SL at capture for 70 razorback sucker
caught from Lake Mohave, Arizona and Nevada, and 31
hatchery-produced, pond- or raceway-reared individuals
from DNFH and WBNFH.
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females; about 50% of SL at capture was attained by the
fifth year. Relative growth was similar in males (Figure 71.
On an absolute basis, however, females attained an average
SL of 140 ± 4 and 276 ± 7 mm at their respective first and
fifth otolith annuli, while males were significantly smaller
(103 ± 4 and 214 ± 8 mm; Student's t-test, p < 0.051.
Marked sexual dimorphism in size of adult razorback sucker
(Gustafson 1975, McAda and Wydoski 1980, Minckley 1983)
is thus established early and continues throughout life. After
the fifth or sixth year, average annual growth in both sexes
slowed to a few millimeters.
Apparently accelerated growth in razorback suckers
which hatched after completion of Davis Dam (Figure 6)
was examined by t-test comparison of means for periods
before and following closure and impoundment of Lake
Mohave in 1951. Mean growth to the first annulus was not
significantly different (males 103 ± 4 before In = 111 and
104:L 9 mm SL after [71; females 136:t 5 [331 and 148 ± 7 mm
SL In = 161), but growth to the fifth apparent annulus
differed significantly (p = < 0.05) for both sexes (males
180 ± 7 [n = 51 and 234 ± 11 mm SL 171; females 256 ± 19
YEARS OF LIFE
Figure 6. Individual growth histories back-calculated from sagitta sections for male (above) and female (below) razorback
sucker caught from Lake Mohave, Arizona and Nevada.