188
C . F. HICKLINU
into the net (Fig. 13). After a couple of hours of fishing, or according
to the state of market demand, the sluices are closed, the catch emptied
out of the net, sorted, and iced for the morrow’s market.
The capture of the fry of the “ Sugpo ” prawn, Penaeus monodon,
in the Philippines has already been described. The fry may be cultivated in company with Chanos, as is more usual, or as a monoculture,
as is now being done by a few large-scale fishpond operators. CacesBorja and Rasalan (1967) show that a more valuable crop is obtained
by the monoculture.
I n both cases, the fry are first reared in nursery ponds a t a high
density, namely, 30-50 per m2, and fed on the “ lab-lab ” for about
14-2 months. They are then transplanted to the growing or rearing
ponds at a much lower rate of stocking, namely 1 per m2 where the
prawn is raised alone, or 1 per 2 m2 where the prawns are being raised
together with Chanos. Thus there must be a very low rate of survival,
and one of the reasons is the difficulty of managing the prawns. Traps
are used to catch the young for transplantation t o the rearing ponds
or the young may be driven from one pond to the other by disturbing
the pond. The prawns burrow readily and have no schooling habit.
There is the same difficulty and loss on harvesting, which may be done
by means of traps or by the same method as used in Singapore, namely,
t o fish at night with a net in the main sluice after the water in the pond
has been raised to the maximum level a t high tide.
Supplementary foods are given, as described earlier, and the giving
of some animal food not only greatly increases the rate of growth, but
also the rate of survival.
The prawns reach commercial size at 5 months to one year of age,
and production is about 250 kg/hectare/annum in monoculture, or
100 kg/hectare/annum when grown with Chanos.
H. Fish and prawn culture in paddy Jields
Pakrasi et a2. (1964) also describe fish and prawn culture in impounded paddy fields in the northern and less saline parts of the delta
of the Ganges. Here, in summer, the inflow of inland drainage water
brings the salinity down to as low as 0.3%,, and the intake of saline
water is restricted to the months of July and August. The fish which
enter the fields with the flood water take refuge in the deep peripheral
ditches, which are also the borrow-pits from which the spoil was taken
to make the embankments. When the salt-resistant varieties of paddy
are planted and the fields are flooded for the growth of the crop, the
fish, which include Tilapia as well as grey mullet and carp species,
C . F. HICKLINU
into the net (Fig. 13). After a couple of hours of fishing, or according
to the state of market demand, the sluices are closed, the catch emptied
out of the net, sorted, and iced for the morrow’s market.
The capture of the fry of the “ Sugpo ” prawn, Penaeus monodon,
in the Philippines has already been described. The fry may be cultivated in company with Chanos, as is more usual, or as a monoculture,
as is now being done by a few large-scale fishpond operators. CacesBorja and Rasalan (1967) show that a more valuable crop is obtained
by the monoculture.
I n both cases, the fry are first reared in nursery ponds a t a high
density, namely, 30-50 per m2, and fed on the “ lab-lab ” for about
14-2 months. They are then transplanted to the growing or rearing
ponds at a much lower rate of stocking, namely 1 per m2 where the
prawn is raised alone, or 1 per 2 m2 where the prawns are being raised
together with Chanos. Thus there must be a very low rate of survival,
and one of the reasons is the difficulty of managing the prawns. Traps
are used to catch the young for transplantation t o the rearing ponds
or the young may be driven from one pond to the other by disturbing
the pond. The prawns burrow readily and have no schooling habit.
There is the same difficulty and loss on harvesting, which may be done
by means of traps or by the same method as used in Singapore, namely,
t o fish at night with a net in the main sluice after the water in the pond
has been raised to the maximum level a t high tide.
Supplementary foods are given, as described earlier, and the giving
of some animal food not only greatly increases the rate of growth, but
also the rate of survival.
The prawns reach commercial size at 5 months to one year of age,
and production is about 250 kg/hectare/annum in monoculture, or
100 kg/hectare/annum when grown with Chanos.
H. Fish and prawn culture in paddy Jields
Pakrasi et a2. (1964) also describe fish and prawn culture in impounded paddy fields in the northern and less saline parts of the delta
of the Ganges. Here, in summer, the inflow of inland drainage water
brings the salinity down to as low as 0.3%,, and the intake of saline
water is restricted to the months of July and August. The fish which
enter the fields with the flood water take refuge in the deep peripheral
ditches, which are also the borrow-pits from which the spoil was taken
to make the embankments. When the salt-resistant varieties of paddy
are planted and the fields are flooded for the growth of the crop, the
fish, which include Tilapia as well as grey mullet and carp species,