8190

• UCREFRP Catalog Number: 8190
• Author: Papoulias, D. and W. L. Minckley
• Title: Effects of Food Availability on Survival and Growth of Larval Razorback Suckers in Ponds
• USFW Year: 1992
• USFW - Doc Type: Transactions of the American Fisheries Society
• Copyright Material: YES

352
PAPOULIAS AND MINCKLEY
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9 14 19 i4'29
Total fish length (mm)
FIGURE 7.-Prey species selection by variously sized
razorback sucker larvae reared in ponds at Dexter Na-
tional Fish Hatchery, New Mexico, 1985, as indicated
by the linear index of selectivity (L;) of Strauss (1979).
(A) rotifers, (B) chironomids, (C) cladocerans, (D) as-
tracods, (E) nauplii, (F) invertebrate eggs, and (G) cope-
pods. Positive (negative) numbers indicate organisms
were more (less) numerous in guts of larvae than in pond.
Closed circles indicate significant differences from zero.
wood Basin (Langhorst and Marsh 1986). Zoo-
plankton densities nonetheless remain low. In
1982, for example, they varied from 27.3 to 44.6
organisms/L in the same areas and times of year
when razorback sucker larvae were present (L. J.
Paulson, University of Nevada, Las Vegas, per-
sonal communication). In 1985, densities aver-
aged only 1.5 organisms/L at the same places lar-
vae were caught. Densities in a cutoff bay inhabited
by larvae were even lower, averaging less than 0.5
potential food items per liter in six samples (Marsh
and Langhorst 1988).
Wild-caught larvae averaged 10.6 mm TL in
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9 14 19 24 29
Total fish length (mm)
FIGURE 8. -Prey-size selection (as body width) by var-
iously sized razorback sucker larvae reared in ponds at
Dexter National Fish Hatchery, New Mexico, 1985, as
indicated by the linear index of selectivity (L;) of Strauss
(1979). Positive (negative) numbers indicate organisms
were more (less) numerous in guts of larvae than in pond.
Closed circles indicate significant differences from zero.
Lake Mohave in 1985, and no growth was re-
corded although the larvae were present from Feb-
ruary through April (Marsh and Langhorst 1988).
Ages of these larvae were unknown, but larvae of
comparable sizes in ponds at Dexter National Fish
Hatchery were 14-21 d old (posthatch) in high-
fertilization treatments at invertebrate densities of
43.3/L, and 21-28 d old in unfertilized ponds at
12.5 organisms/L. In the cutoff bay where zoo-
plankton density was less than 0.5/L, larvae grew
to a mean TL of about 16.0 mm in 69 d. Larvae
at Dexter achieved 16.0 mm TL in unfertilized
ponds 49 d from hatching. In the laboratory, lar-
vae grew to 16.0 mm in 57 d at densities of 50
Artemia nauplii/L (Papoulias and Minckley 1990).
Perhaps larval density in the bay was low and (if
razorback sucker larvae are efficient hunters, as
suggested above) the larvae found enough food to
survive and grow. The slightly slower growth to
16.0 mm compared with that at Dexter (69 versus
49 d) may support this possibility.
Papoulias and Minckley (1990) concluded that
razorback sucker larvae reared in the laboratory