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3    5   7   9   11   13  15   17  19   21  23   25
Days posthatch
Figure 1. Average daily mortality of walleye fry
fed two diets.
P=0.83). Cannibalism, or unaccounted mortality, was
higher in tanks fed WS 0201 (21%) compared to
those fed BioKyowa (11%, P=0.045).
Daily mortality in BioKyowa and WS tanks
began to increase on day 7 posthatch and by day 1O
both treatments had declined (Figure 1). However,
one tank fed the WS 0201 diet had unusually high
mortality for three days starting on day 13, but the
cause could not be determined.
Initial length of fly in this study was 8.3 mm. Fry
length began to differentiate at day 12 posthatch, with
length of fry fed BioKyowa (14.4 mm) exceeding
that of WS 0201 (12.8 mm, P<0.0001, Table 2). The
percentage of fry with FIG was significantly lower in
tanks fed WS 0201 (29.3%) compared to tanks fed
BioKyowa (78%, P=0.0017). At the end of the study,
fry fed the BioKyowa were, on average, 3.8 mm
longer than fry fed WS 0201 diet.
Table 2. Mean length, gas bladder inflation (GBI), and
diets.
Performance
variable
Length (mm)
GBI (%)
FIG (%)
DPH
7
12
16
21
26
7
12
16
21
26
7
12
16
21
26
BioKyowa
10.4
14.4
16.6
21.9
27.2
79.3
100
100
100
100
78.3
97.3
100
93.5
100
A deformity became apparent in fry fed WS
0201 near the end of the study. About 2% of the fish
had an arched back posterior to the head, which
caused deformed fish to swim on their side.
Discussion. These findings show that walleye fry fed
WS 0201 did not perform as well as fry fed
BioKyowa B-series diet. Fry fed BioKyowa had
better survival and growth compared with WS 0201.
Cannibalism was nearly double in the WS fed fry
compared to that of BioKyowa fed fry. The effect of
ingredients substitutions in the WS diets could not be
determined through a direct comparison because of
unavailability of some ingredients.
The percentage of fish fed WS 0201 with FIG on
day 7 posthatch was 62% lower than the rate of FIG
for fish fed BioKyowa. The reduced feed intake may
be due to poor palatability of WS 0201 which may
have resulted in the higher cannibalism rates
observed in tanks fed WS 0201.
Experimental walleye starter diet formulations
continue to produce growth problems for larval
walleye. Intensive walleye fry culture on formulated
diets may be limited without BioKyowa.
Unfortunately, this research has not yielded a diet
which performed as well as BioKyowa FFK B-series.
Acknowledgements. This work was supported by the
Federal Aid in Sport Fish Restoration Program,
project number F-106-R.
References. Moore, A.A., M.A. Prange, B.T.
Bristow, and R.C. Summerfelt. 1994. Influence of
stocking densities on walleye fry viability in
experimental and production tanks. Progressive Fish
Culturist. 56:194-201.
feed acceptance (feed in gut, FIG) of larval walleye fed two
Diet
WS 0201
10.3
12.8
14.8
18.8
23.4
88.3
98.6
100
100
100
29.3
75.7
100
97.4
100
P-value
0.5582
<0.0001
0.0003
0.0003
0.0011
0.2023
0.3739
0.0017
0.4261
0.2427
38
. .
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.
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