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

348
d
a
E
3
Z
0
100
so
PAPOULIAS AND MINCKLEY
A
,00
50
0

,4f] L?ik
100
d
E
2 50
C
0
0
B
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4 6
Week
Cladocerans ® Chironomids
® Ostracods Eggs
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50
YI
a Rotifers
Copepods
Week
® Nauplii
Other
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FIGURE 4.-Percentage numerical composition (A-C) and percentage volumetric composition (D-F) of diets of
larval razorback suckers reared in ponds fertilized at low (A, D), medium (B, E), and high (C, F) levels at Dexter
National Fish Hatchery, New Mexico, 1985.
on them (this study), had no discernible effect on
survival or growth of young razorback suckers.
Overall survival of razorback sucker larvae was
high, averaging 77.5 ± 6.3% for the 50-d experi-
ment. During this time, mean invertebrate den-
sities were about 13 organisms/L in unfertilized
ponds, 24/L in ponds with medium fertilization,
and 43/L in highly fertilized ponds. In laboratory
studies (Papoulias and Minckley 1990), 80% sur-
vival was attained by razorback suckers fed 6 Af`-
temia Salina nauplii/L per larva per day over a
period of 50 d. Larval lake whitefish (see Table 4
for scientific names) had 80-100% survival on a
daily ration of at least 64 zooplankters/L per larva
(Taylor and Freeberg 1984); plaice survival was
72% on a daily ration of 50 Artemia saliva nau-
plii/L per larva (Wyatt 1972). Duration of the last
two experiments was half that of our razorback
sucker trials or less. In contrast, only 54% of white
suckers survived on daily diets of about 550 or-
ganisms/L per larva (Hart and Werner 1987), and
most other species for which we could find com-
parable data required even greater numbers of food
organisms to attain this survival level (Table 4).
In a 28-d pond study, 63% of larval striped bass
survived at a mean zooplankton density of about
650 organisms/L, and 46% survived at a prey den-
sity of about 250/L (Geiger et al. 1985).
Razorback sucker larvae thus may have mark-
edly greater survival at lower food densities than
other species, and such nutritional efficiency may
be adaptive. The species' original habitat was in
backwaters and channels of turbid, fluctuating,
unpredictable desert rivers (Minckley et al., in
press). Larvae appear in greatest abundance in
February and March in Lake Mohave. In desert
streams, such timing would correspond to the later
part of a long period of low flow that began the
previous summer (Turner and Karpiscak 1980),
and it would be a time of relatively high potential
food supplies in such sandy-bottomed, plankton-
poor habitats. Snowmelt typically resulted in