ESTUARIKE FISH FARMING
155
vironment where they breed. I n pond culture, they are carried into
the ponds with the water, and there is no control over their numbers
(save that the more the better). Schuster can hardly imagine overstocking with prawn larvae, and mortality must be very heavy if of
the millions which may enter a pond only enough survive to give a
crop of 100-1 000 kg of well-grown adults. Management measures are
designed to attract the maximum number of juveniles.
IV. SOURCES OF YOUNG FISH AND PRAWNS
A. Non-breeding and artificial breeding
1. Pish
It is a notable fact that none of the fish cultured in brackish-water
ponds will breed in the ponds except Tilapia. The young of the salmonids must be bred in fresh water, those of the yellow tail are caught in
the sea, those of Chanos, grey mullets and prawns in brackish-water
creeks and lagoons. So a specialist fry fishery has arisen which will
be described later.
The industry’s needs for healthy living fry are very great, and a
shortage and uncertainty of supply are one of its worst handicaps. Lin
(1968) shows in a table that the availability of Chanos fry in Taiwan, as
caught by the local fry fishermen, varied from 14 million in 1934 to
204 million in 1958. Requirements are about 160 million fry a year.
It may be necessary to import fry from the Philippines, where there is
always a surplus. I n the same way, there is a shortage of Chanos fry
in Java, and the deficit has to be made good by importing fry the long
distance from Madura. According to Schuster, Java needs 190-200
million Chanos fry annually. The catch of Chanos fry in the Philippines
exceeds 440 million (Bunag, 1957) but more are needed.
As to grey mullet, Tang (1964) estimates the requirements of
Taiwan at 10 million annually. Hong Kong requires some hundreds
of thousands of mullet fry if the stocking rate is 3 000 per acre. I n
Italy it is no longer possible to rely on local supplies of grey mullet
fry for stocking the valli, and additional fry have to be imported
from lagoons on the Tyrrhenian Sea on the west coast of Italy. The
prosperity of brackish-water fish farming must remain precarious so
long as it has to rely on naturally-spawned fry.
Naturally, many attempts are being made to breed these fish.
There is promise of success with the striped grey mullet, Mugil cephalus,
but no success has been reported with Chanos as yet, though it will
grow to full size in ponds. The gonads are said not to ripen in ponds;
however, the same was said of the major Chinese and Indian carps,
155
vironment where they breed. I n pond culture, they are carried into
the ponds with the water, and there is no control over their numbers
(save that the more the better). Schuster can hardly imagine overstocking with prawn larvae, and mortality must be very heavy if of
the millions which may enter a pond only enough survive to give a
crop of 100-1 000 kg of well-grown adults. Management measures are
designed to attract the maximum number of juveniles.
IV. SOURCES OF YOUNG FISH AND PRAWNS
A. Non-breeding and artificial breeding
1. Pish
It is a notable fact that none of the fish cultured in brackish-water
ponds will breed in the ponds except Tilapia. The young of the salmonids must be bred in fresh water, those of the yellow tail are caught in
the sea, those of Chanos, grey mullets and prawns in brackish-water
creeks and lagoons. So a specialist fry fishery has arisen which will
be described later.
The industry’s needs for healthy living fry are very great, and a
shortage and uncertainty of supply are one of its worst handicaps. Lin
(1968) shows in a table that the availability of Chanos fry in Taiwan, as
caught by the local fry fishermen, varied from 14 million in 1934 to
204 million in 1958. Requirements are about 160 million fry a year.
It may be necessary to import fry from the Philippines, where there is
always a surplus. I n the same way, there is a shortage of Chanos fry
in Java, and the deficit has to be made good by importing fry the long
distance from Madura. According to Schuster, Java needs 190-200
million Chanos fry annually. The catch of Chanos fry in the Philippines
exceeds 440 million (Bunag, 1957) but more are needed.
As to grey mullet, Tang (1964) estimates the requirements of
Taiwan at 10 million annually. Hong Kong requires some hundreds
of thousands of mullet fry if the stocking rate is 3 000 per acre. I n
Italy it is no longer possible to rely on local supplies of grey mullet
fry for stocking the valli, and additional fry have to be imported
from lagoons on the Tyrrhenian Sea on the west coast of Italy. The
prosperity of brackish-water fish farming must remain precarious so
long as it has to rely on naturally-spawned fry.
Naturally, many attempts are being made to breed these fish.
There is promise of success with the striped grey mullet, Mugil cephalus,
but no success has been reported with Chanos as yet, though it will
grow to full size in ponds. The gonads are said not to ripen in ponds;
however, the same was said of the major Chinese and Indian carps,