,
3315
One
of
the
in inæensive æarp
rearing
is
eutrophication due to fish waste products. Net cage culture has been said to
é‘hëôù”fàgè
in 'LàkÎè
Kasumigaura increased from
Carp
production by net cage in this lake was negligible in l968_and r0se to over 7
800.tons in—1979. The total N and P burdens of the lake
were
11.50
and
respectively,
with ll% of the total N and 24% of the total
P originating from net cage culture bÏ
(Ibaraki Prefecture,
Eut.rophicatiom… often caused: …a…la'ck of…
summer, which in 1973…killed
1,500 tons (37%) of the carp in this lake alone.Pollution is also caused by
fish culture in farm or irrigation ponds and in‘running—water ponds; The
outflowing water contains abundant waste produCts from fiSh and raises the
COD of the
rivers.
In
farm
or
irrigation
the upper water layer
commonly contains an abundance of phytoplankton, while the lower layer con—
tains
decomposing organic matter. Whenäthe fish are
the
this water is drained off into rivers.
B —
Protein for feeds
È£T
The secOnd
important problem
carp rearing is!a shortagè of
cheap animal protein for fish feeds. This protein source is mainly
fishmeal
made
from cod or flatfish.
marine resources whidh supply this
fishmeal have not been able to meet the increased demand for pelleted feed.
The
coStëbf this
contributed to the steep rise in
producing carp. In addition, the supply of silkworm pupae, which is an impor—
tant
prbtèih source for carp in Japan,
has
recently decreased coSiderably
tic fibGI‘S.
,
:"z<:;:‘:‘s»;€
? ;, ï Î'î*=*‘°‘Ï
,x
IV — INCREASE OF FEED—CONVERSION EFFICIENCY BY GENETIC
ImproVing the
and
fr0m
bo
cmos S»…'v(JY am a t;o:æ$‘» end à …u lït i;»pläe
S“-‘i [: (‘ Y amatoæ- X= f “S
“an
)% :x: ‘( wil&df%“?ä mirror ?Èf)$]‘u
f=_a St
@
nv e‘rÏtâ f eed“= % m O‘ï‘Ï—è» efïfii+
Ciently than any of the parent races or any of the various other hybrids
tested (Table 3). In particular, these multiple—cross hybrids convert feed at
least 30% more efficiently
than the widely cultivated yamato
The
survival rate of the multiple—cross hybrids was 96% during
rearing test (Suzuki and Yamaguchi, 1980);If all Japanese carp farmers were
amount
of feed required would be reduced by at
year! This
figure was computed on the basis that the total production of carp in
year
70%…3i}n ath“e y.aîmat®
C à @ A:i f—ii mpî‘no»ÿ è
lnt hein
= eÏ"f fl C 1
“?
“ M
1 p t °
reduce fish waste products that Cause water pollution… At present;îmany
farmers are planning to cultivateïyamato+mirror F1_or multiple—cross hybr1ds.
…
3315
One
of
the
in inæensive æarp
rearing
is
eutrophication due to fish waste products. Net cage culture has been said to
é‘hëôù”fàgè
in 'LàkÎè
Kasumigaura increased from
Carp
production by net cage in this lake was negligible in l968_and r0se to over 7
800.tons in—1979. The total N and P burdens of the lake
were
11.50
and
respectively,
with ll% of the total N and 24% of the total
P originating from net cage culture bÏ
(Ibaraki Prefecture,
Eut.rophicatiom… often caused: …a…la'ck of…
summer, which in 1973…killed
1,500 tons (37%) of the carp in this lake alone.Pollution is also caused by
fish culture in farm or irrigation ponds and in‘running—water ponds; The
outflowing water contains abundant waste produCts from fiSh and raises the
COD of the
rivers.
In
farm
or
irrigation
the upper water layer
commonly contains an abundance of phytoplankton, while the lower layer con—
tains
decomposing organic matter. Whenäthe fish are
the
this water is drained off into rivers.
B —
Protein for feeds
È£T
The secOnd
important problem
carp rearing is!a shortagè of
cheap animal protein for fish feeds. This protein source is mainly
fishmeal
made
from cod or flatfish.
marine resources whidh supply this
fishmeal have not been able to meet the increased demand for pelleted feed.
The
coStëbf this
contributed to the steep rise in
producing carp. In addition, the supply of silkworm pupae, which is an impor—
tant
prbtèih source for carp in Japan,
has
recently decreased coSiderably
tic fibGI‘S.
,
:"z<:;:‘:‘s»;€
? ;, ï Î'î*=*‘°‘Ï
,x
IV — INCREASE OF FEED—CONVERSION EFFICIENCY BY GENETIC
ImproVing the
and
fr0m
bo
cmos S»…'v(JY am a t;o:æ$‘» end à …u lït i;»pläe
S“-‘i [: (‘ Y amatoæ- X= f “S
“an
)% :x: ‘( wil&df%“?ä mirror ?Èf)$]‘u
f=_a St
@
nv e‘rÏtâ f eed“= % m O‘ï‘Ï—è» efïfii+
Ciently than any of the parent races or any of the various other hybrids
tested (Table 3). In particular, these multiple—cross hybrids convert feed at
least 30% more efficiently
than the widely cultivated yamato
The
survival rate of the multiple—cross hybrids was 96% during
rearing test (Suzuki and Yamaguchi, 1980);If all Japanese carp farmers were
amount
of feed required would be reduced by at
year! This
figure was computed on the basis that the total production of carp in
year
70%…3i}n ath“e y.aîmat®
C à @ A:i f—ii mpî‘no»ÿ è
lnt hein
= eÏ"f fl C 1
“?
“ M
1 p t °
reduce fish waste products that Cause water pollution… At present;îmany
farmers are planning to cultivateïyamato+mirror F1_or multiple—cross hybr1ds.
…