350
'
L.,Sifa
…
‘
Therefore, by choosing bighead and silver carp as the principle species,
primary production can be fully utilized. The biomass of macrophytes and
benthos is poor in most resérvoirs, For example, the range of the
biomass is 0.004—17.97
(Li, unpublished data) ; therefore
bivdrous and benthophagous fish are stocked, except in a few
abundant benthos or macrophytes where more grass carp, common carp
crucian carp
(Carassius auratus) are stocked.
the dominant fish population is piscivorous, fish yeeld is
Thus pisciv0rous fish are not widely cultured at present. Because the
duction of bighead ans silver carp occupies a large part of the
production in reservoirs, the proper stocking proportion of these two
cies is highly
For example, in the Qingshan reservoir
of culture area, common Carp was the principle stock fish in the
and production was lower (14 kg/ha/year in 1961). Later, the major
used were bighead and silver carp, and fish yield increased
After some years,
a
suitable proportion of silver carp (3—4) and of highead
(7—6) was determined and annual production rose (641Î138
and
1983.
'
‘
‘
“
‘
‘
‘
'
—
Practice has shown that bighead is better than silver carp in most re—
servoirs as Concerns individual growth rate and mass production; This
quite different than found for ponds. In intensive culture ponds, the
mal carrying load for silver carp is usually 4 500 kg/ha (Y. Li,
for bighead it is only oué—third to one+fourth of that. The
bighead in'reservoirs has attractéd the attention of fish biologists
some
related Studies have began. Possible reasons may be: (1) the
proporti0n
of
is higher than in ponds (Li,
data); (2) for the same body size, the oxygen consumption of the
lower (Liu and Chen 1975); (3) the energy conversion effiéiehcy of
planhton is higher (Wang and Liang, 1981); (4) bighead may have
sources yet to be determined.
‘,
Stdcking density
f
'
In
êt0çkîg
Pr°düçtïoñfhàS bèénf
Wih‘stôçking dé_nëitYWlthm
the possibilities of food availability; if the stocking density exceeds a
'
reasonable limit, the yield will be less and the fish Will be stunted and
not
meet marketing requirements (Fig. 1); To reach a given marketable
Within a given time, stocking size must be restricted to an optinùm I3ÎÎU
Wh€—ïî.‘î
shing ,si,Z€
all.
i
‘
’
E°?€ &; 1ngtmeg:thedtemnatnfstockngdenstyandmxmgœtl
of ‘bighead ana “silver càrp‘"
à aà1ÿé‘îs ofthe
harvest.
If the fish grew faster, meaning that f56d‘wàé abundant,
ger11ngs could be stocked or the proportion of that species increased the
neX'} Year, or Vice versa. In this way, stocking was
until a good
The Successful
°??? »…;«1
13 2 cmlength …(total)
mixing :.ratio
::vafter
°ne‘ thkngThbdywght fbghdhu11de751gd
helP vlutfhputvtyptullythtf 1vpdbg
head(HeadLl
Bâé‘iëà1‘1yï“
ÈQ
the amount of
tes and îltsutlhzat10nefflcœnCY,
Ï,Ï Ï ÏÎ
ÏÎ
1Ll
: …
—
"
{fl Ïj
"
…
…
'
11
,1
…
1,
11
.
.
11111
'
L.,Sifa
…
‘
Therefore, by choosing bighead and silver carp as the principle species,
primary production can be fully utilized. The biomass of macrophytes and
benthos is poor in most resérvoirs, For example, the range of the
biomass is 0.004—17.97
(Li, unpublished data) ; therefore
bivdrous and benthophagous fish are stocked, except in a few
abundant benthos or macrophytes where more grass carp, common carp
crucian carp
(Carassius auratus) are stocked.
the dominant fish population is piscivorous, fish yeeld is
Thus pisciv0rous fish are not widely cultured at present. Because the
duction of bighead ans silver carp occupies a large part of the
production in reservoirs, the proper stocking proportion of these two
cies is highly
For example, in the Qingshan reservoir
of culture area, common Carp was the principle stock fish in the
and production was lower (14 kg/ha/year in 1961). Later, the major
used were bighead and silver carp, and fish yield increased
After some years,
a
suitable proportion of silver carp (3—4) and of highead
(7—6) was determined and annual production rose (641Î138
and
1983.
'
‘
‘
“
‘
‘
‘
'
—
Practice has shown that bighead is better than silver carp in most re—
servoirs as Concerns individual growth rate and mass production; This
quite different than found for ponds. In intensive culture ponds, the
mal carrying load for silver carp is usually 4 500 kg/ha (Y. Li,
for bighead it is only oué—third to one+fourth of that. The
bighead in'reservoirs has attractéd the attention of fish biologists
some
related Studies have began. Possible reasons may be: (1) the
proporti0n
of
is higher than in ponds (Li,
data); (2) for the same body size, the oxygen consumption of the
lower (Liu and Chen 1975); (3) the energy conversion effiéiehcy of
planhton is higher (Wang and Liang, 1981); (4) bighead may have
sources yet to be determined.
‘,
Stdcking density
f
'
In
êt0çkîg
Pr°düçtïoñfhàS bèénf
Wih‘stôçking dé_nëitYWlthm
the possibilities of food availability; if the stocking density exceeds a
'
reasonable limit, the yield will be less and the fish Will be stunted and
not
meet marketing requirements (Fig. 1); To reach a given marketable
Within a given time, stocking size must be restricted to an optinùm I3ÎÎU
Wh€—ïî.‘î
shing ,si,Z€
all.
i
‘
’
E°?€ &; 1ngtmeg:thedtemnatnfstockngdenstyandmxmgœtl
of ‘bighead ana “silver càrp‘"
à aà1ÿé‘îs ofthe
harvest.
If the fish grew faster, meaning that f56d‘wàé abundant,
ger11ngs could be stocked or the proportion of that species increased the
neX'} Year, or Vice versa. In this way, stocking was
until a good
The Successful
°??? »…;«1
13 2 cmlength …(total)
mixing :.ratio
::vafter
°ne‘ thkngThbdywght fbghdhu11de751gd
helP vlutfhputvtyptullythtf 1vpdbg
head(HeadLl
Bâé‘iëà1‘1yï“
ÈQ
the amount of
tes and îltsutlhzat10nefflcœnCY,
Ï,Ï Ï ÏÎ
ÏÎ
1Ll
: …
—
"
{fl Ïj
"
…
…
'
11
,1
…
1,
11
.
.
11111