ESTUARINE FISH FARMING
185
operator considers that the pond is sufficiently stocked, the gates are
closed, and the supplementary gaps in the embankments are also
stopped up. From April to September, the work consists of maintaining
a working depth of water, repair and maintenance work, and guarding
against thieves.
Where a bheri has several compartments, as in the one studied by
Pillay (1954), the water is distributed equally between them, and where
there are nursery ponds, the small fry are guided to them by the water
flow. The salinities of the bheris vary from 24.5-35.0%, (Pillay) or even
36%, and above in the summer (Pakrasi et al.).
The principal fish whose fry are swept into the ponds with the inflowing water are two species of grey mullet (Mugil parsia [Blkr] and
M . tade), two predatory fish, Lates calcarifer (Blkr) and Mystus gulio
(Hamilton), Pristiopoma hasta (Blkr), and prawns, which are among
the most valuable of the products of the ponds. With the presence of
powerful predators such as Lates, a considerable proportion of the
other small fish and prawns must be sacrificed as food. Schuster
estimates that each lb of Lates is gained at the expense of 8Ib of
other fish, but as Lates is a highly-priced fish some sacrifice is
justified.
During the summer months, there is some subsistence fishing in the
ponds, but the serious fishing begins in September. Additional fishermen may be taken on, and the ponds are gradually drained. During
draining, fishing may be done with seines and gillnets into which the
fish are beaten, but as the ponds empty the remaining fish collect in
the deeper ditches and are induced to enter non-return traps by a
current of water.
Marketing and transport are a problem, and the deep ditches used
as nursery ponds in the spring may be pressed into service as storage
tanks in which the fish can be kept alive until transport and markets
are available. I n a hot climate this is a matter of urgency.
One interesting way of catching the fish in these ponds is used in
one form or another the world over. Cut brushwood is heaped up in
the pond and the fish take shelter in these, partly for protection, and
partly for food, since the brushwood will be a good substrate for the
growth of the algal felts on which fish depend directly or indirectly.
When fishing is to take place, the heaps of brushwood are surrounded
by nets and the brushwood removed.
During the winter the ponds lie dry, and may also be tilled. This
is known to encourage the growth of blue-green algae and to assist in
the fixation of atmospheric nitrogen and to mineralize the organic
material in the pond soil.
185
operator considers that the pond is sufficiently stocked, the gates are
closed, and the supplementary gaps in the embankments are also
stopped up. From April to September, the work consists of maintaining
a working depth of water, repair and maintenance work, and guarding
against thieves.
Where a bheri has several compartments, as in the one studied by
Pillay (1954), the water is distributed equally between them, and where
there are nursery ponds, the small fry are guided to them by the water
flow. The salinities of the bheris vary from 24.5-35.0%, (Pillay) or even
36%, and above in the summer (Pakrasi et al.).
The principal fish whose fry are swept into the ponds with the inflowing water are two species of grey mullet (Mugil parsia [Blkr] and
M . tade), two predatory fish, Lates calcarifer (Blkr) and Mystus gulio
(Hamilton), Pristiopoma hasta (Blkr), and prawns, which are among
the most valuable of the products of the ponds. With the presence of
powerful predators such as Lates, a considerable proportion of the
other small fish and prawns must be sacrificed as food. Schuster
estimates that each lb of Lates is gained at the expense of 8Ib of
other fish, but as Lates is a highly-priced fish some sacrifice is
justified.
During the summer months, there is some subsistence fishing in the
ponds, but the serious fishing begins in September. Additional fishermen may be taken on, and the ponds are gradually drained. During
draining, fishing may be done with seines and gillnets into which the
fish are beaten, but as the ponds empty the remaining fish collect in
the deeper ditches and are induced to enter non-return traps by a
current of water.
Marketing and transport are a problem, and the deep ditches used
as nursery ponds in the spring may be pressed into service as storage
tanks in which the fish can be kept alive until transport and markets
are available. I n a hot climate this is a matter of urgency.
One interesting way of catching the fish in these ponds is used in
one form or another the world over. Cut brushwood is heaped up in
the pond and the fish take shelter in these, partly for protection, and
partly for food, since the brushwood will be a good substrate for the
growth of the algal felts on which fish depend directly or indirectly.
When fishing is to take place, the heaps of brushwood are surrounded
by nets and the brushwood removed.
During the winter the ponds lie dry, and may also be tilled. This
is known to encourage the growth of blue-green algae and to assist in
the fixation of atmospheric nitrogen and to mineralize the organic
material in the pond soil.