Researchers from the Prefectural University
of Kumamoto in Japan conducted DO control
experiments in a fish farm on red seabream
with the microbubble generating system in
Kusuura Bay, Amakusa, Kumamoto Prefecture,
Kyushu, western Japan, between 2003 and
2007. The water depth of the bay was between
16 and 20 m at the centre of the bay. The
annual temperature of the surface water
ranged from 19.7°C to 29.3°C between May
and October 2007. This study was financially
supported by a Research and Development
Program for New Bio-industry Initiatives
of the Bio-oriented Technology Research
Advancement Institution of Japan.
The results of the experiments indicate that
the control of DO levels of water in the net pen
using the microbubble generator improved
the growth rate of the fish significantly. In the
control net pen, the body weight of the fish
was 1.25 ± 0.17 kg in wet weight (mean ± SD,
n = 30) at the beginning of the experiment
on June 18, 2007, and they gained 1.39 ±
0.25 kg and 1.70 ± 0.26 kg by August 8 (50
days later) and October 3, 2007 (108 days
AgriKultuur |AgriCulture
later), respectively. In the experimental net
pen, the body weight of the fish was 1.19 ±
0.24 kg in wet weight (mean ± SD, n = 30),
slightly lighter than that of the control net
pen at the beginning of the experiment. The
difference in the mean body weight between
the experimental net pen and the control
net pen was not statistically significant (p =
0.15, Mann–Whitney’s U test, n = 30). The fish
grew faster than that in the control net pen.
The body weight reached 1.83 ± 0.21 kg in
wet weight at the end of the experiment (108
days later), which was 0.13 kg heavier than
that in the control net pen. The difference
in body weight between these two net pens
was statistically significant (p = 0.02, Mann–
Whitney’s U test, n = 30). The increase in the
body weight of the fish in the experimental
net pen during the period of the experiment
for 108 days was 0.64 kg in wet weight, which
was 42% more than that in the control net pen
(0.45 kg).
In the experimental net pen, the body weight
of the fish was 1.33 ± 0.22 kg in wet weight
(mean ± SD, n = 30), slightly heavier than that
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