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

344
E
7
Z
0-
4
Week
Cladocerans
® Ostracods
PAPOULIAS AND MINCKLEY
A
B
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E
7
6
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100
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Week
® Chironomids Rotifers Nauplii
Eggs Copepods Other
FIGURE 1.-Percentage numerical composition (A-C) and percentage biovolumetric composition (D-F) of various
invertebrates in ponds fertilized at low (A, D), medium (13, E), and high (C, F) levels at Dexter National Fish
Hatchery, New Mexico, 1985.
Length-weight (TL-WT) relationships were the
same for all treatments. The overall relationship
for razorback suckers between 9.4 and 27.3 mm
TL (r2 = 0.98) is described by the equation:
log,o(WT) _ -3.452 + 3.978 log,a(TL).
Three of four ponds in each treatment were col-
onized by salamander larvae. Although their per-
hectare numbers and biomass were positively
correlated with treatment (low, 723 ± 423 indi-
viduals and 2,050 ± 1,418 g; medium, 2,768 ±
967 individuals and 2,132 ± 2,134 g; high, 7,514
± 6,443 individuals and 14,156 ± 13,550 g), vari-
ation was so great that differences were not sig-
nificant (for numbers, F = 0.85, P = 0.46; for
biomass F = 0.71, P = 0.52). A positive corre-
lation between razorback sucker biomass and
treatment (r = 0.66) was increased only slightly
(r = 0.68) when salamanders were added. While
not quantified, razorback sucker larvae were noted
in a few salamander stomachs.
Foods and feeding. -The specific developmen-
tal point at which larval razorback suckers began
feeding was not determined. However, of 172 fish
total examined from all ponds during week 1 (7-
13 d posthatch), 95 (55%) retained yolk, and of
these, 31 (33%) had empty guts. During week 1,
there were no differences in percentage empty
stomachs among treatments (F = 0.04, P = 0.97),
nor were there treatment or day-versus-night dif-
ferences for amounts of food eaten (P = 0.59, P
= 0.99, respectively).
Razorback sucker larvae initially ate sessile di-
atoms, phytoplankton, and detritus (Table 3).
However, by the end of week 1 (12 d posthatch)
rotifers, nauplii, cladocerans, eggs, and chiron-
omid dipteran larvae began to increase in fre-
quency in diets. At the beginning of week 2 (15 d
posthatch), no yolk was evident in any larva.
Chironomids and rotifers dominated volumet-
rically in larvae from all treatments in week 2,
and cladocerans became important in larvae from