348
L. Sifa
INTRODUCTÎON
Pond fish culture in China has a long history, but reservoir fish cul—
ture
only started about 30 years ago as a significant food production system.
Before
1949, there were no reservoirs in China involved in fish culture and
only a few with fishing activities. After that, with the rapid development
of water conservation facilities, many reservoirs were built. Reservoir fish—
fisheries have developed rapidly and are now the third most important source
of freshwater fish in China; pond and lake fish are the most important.
At present,
there are more
than 86
100 reservoirs in China (Liu, 1983).
Of
these, about 300 are large reservoirs (volume: over 107 mJ), about 2 100
are
medium—sized
(volume:
106—107 m3) and about 83 000 are small reservoirs
(Liu, 1983). Besides electric power, flood control, irrigation, navigation,
water
supply for city and factory, fish culture is an important item in the
multipurpose use of reservoirs.
The
suitable culture area of all reservoirs is about 2.106 ha, i.e.
about 40 % of all the total suitable freshwater culture area in China.
Since
only about 15 % of the hydroelectric power potential has been harnessed so
for, the number and area of reservoirs will be increased in the future. It
is important for fishery biologists to utilize these new waters to produce
fish protein. In order to use the reservoirs, fisheries scientists have done
a
lot of research and investigation in the past 30 years and have achieved
some
major breakthroughs: the successful artificial propagation of Chinese
farmed fish
(including the utilization of natural brood stocks for artifi—
cial propagation) has been basically resolved; the enclosed portions of
reservoir waters and cages for fingerling rearing have been used success—
fully to replace nursing and rearing ponds; fishing methods were developed
for driving, blocking, netting and trapping to harvest surface—layer dwel—
lers, including plankton feeders such as silver carp (Hypophythalmichthys
molitrix) and bighead (Aristichthys nobilis); net
have been developed as anti—escage fâÊiÏifies; research has been done on the
ecology of predators and fishing activities athat have led to management
techniques. Now, reservoir fish culture is turning from empirical to scientific culture.
ECOLOGICAL BASIS OF RESERVOIR FISH CULTURE
The main aim of reservoir fish culture in China is to produce table
fish. The ecological principle of fish production in reservoirs can be sum—
marized as (A) action directed towards efficient use of resources, and (B)
action
to
shorten the food chain of fish production and to utilize the tro—
phic niche fully.
A- …
1) ÊËEËËÈÊJËÊÏËËÏËŒÉLÊËÊÊGSses in reservoirs
].
Reservoirs have both allochthonous and autochthonous organic mater1al.
In the first years of impoundment, allochthonous sources are more
important,
whereas in the years just after that, autochthonous sources be—
come
slightly more important.
Energy and matter flow through a reservoir ecosystem; aquatiC pro—
dUCt10 processes take place in a dynamic water body. Because of the flow
pattern,
much of
the organic and nutrient input from the catchment area
s1nks
to
the bottom. Dissolved fractions enter the aquatic production
processes
but due to water movement and exchange, many nutrients,
food organisms
and even fish are lost (plus fishing mortality).
L. Sifa
INTRODUCTÎON
Pond fish culture in China has a long history, but reservoir fish cul—
ture
only started about 30 years ago as a significant food production system.
Before
1949, there were no reservoirs in China involved in fish culture and
only a few with fishing activities. After that, with the rapid development
of water conservation facilities, many reservoirs were built. Reservoir fish—
fisheries have developed rapidly and are now the third most important source
of freshwater fish in China; pond and lake fish are the most important.
At present,
there are more
than 86
100 reservoirs in China (Liu, 1983).
Of
these, about 300 are large reservoirs (volume: over 107 mJ), about 2 100
are
medium—sized
(volume:
106—107 m3) and about 83 000 are small reservoirs
(Liu, 1983). Besides electric power, flood control, irrigation, navigation,
water
supply for city and factory, fish culture is an important item in the
multipurpose use of reservoirs.
The
suitable culture area of all reservoirs is about 2.106 ha, i.e.
about 40 % of all the total suitable freshwater culture area in China.
Since
only about 15 % of the hydroelectric power potential has been harnessed so
for, the number and area of reservoirs will be increased in the future. It
is important for fishery biologists to utilize these new waters to produce
fish protein. In order to use the reservoirs, fisheries scientists have done
a
lot of research and investigation in the past 30 years and have achieved
some
major breakthroughs: the successful artificial propagation of Chinese
farmed fish
(including the utilization of natural brood stocks for artifi—
cial propagation) has been basically resolved; the enclosed portions of
reservoir waters and cages for fingerling rearing have been used success—
fully to replace nursing and rearing ponds; fishing methods were developed
for driving, blocking, netting and trapping to harvest surface—layer dwel—
lers, including plankton feeders such as silver carp (Hypophythalmichthys
molitrix) and bighead (Aristichthys nobilis); net
have been developed as anti—escage fâÊiÏifies; research has been done on the
ecology of predators and fishing activities athat have led to management
techniques. Now, reservoir fish culture is turning from empirical to scientific culture.
ECOLOGICAL BASIS OF RESERVOIR FISH CULTURE
The main aim of reservoir fish culture in China is to produce table
fish. The ecological principle of fish production in reservoirs can be sum—
marized as (A) action directed towards efficient use of resources, and (B)
action
to
shorten the food chain of fish production and to utilize the tro—
phic niche fully.
A- …
1) ÊËEËËÈÊJËÊÏËËÏËŒÉLÊËÊÊGSses in reservoirs
].
Reservoirs have both allochthonous and autochthonous organic mater1al.
In the first years of impoundment, allochthonous sources are more
important,
whereas in the years just after that, autochthonous sources be—
come
slightly more important.
Energy and matter flow through a reservoir ecosystem; aquatiC pro—
dUCt10 processes take place in a dynamic water body. Because of the flow
pattern,
much of
the organic and nutrient input from the catchment area
s1nks
to
the bottom. Dissolved fractions enter the aquatic production
processes
but due to water movement and exchange, many nutrients,
food organisms
and even fish are lost (plus fishing mortality).