ESTUARINE FISH FARMING
163
brackish water (Fig. 11). The young fish stay long enough in the
trenches to become accustomed to the climate of the valli. When strong
enough, they are free (as in the Chanos wintering ponds) to swim out
into the main growing pond.
I n the Russian limans, the first grey mullet fry to ascend the channels from the sea to the lagoon are those of the golden grey mullet,
Liza aurata, and these may be caught by lift-nets or seines to be
counted. Any surplus may be sold while, if there is a deficit, more fry
may have to be bought (Zambribortch, 1962; Ilin, 1954). Later in the
season, the ascending fry include a proportion of Mugil cephalus and
M . saliens, and these late migrants will not have had time to grow to
a commercially acceptable size by winter. Zambribortch thinks that
inadequate stocking with fry is one of the chief reasons for the poor
performance of the limans as fish farms, and he describes wintering
ponds in which these late arrivals can be kept alive, and so be available
to supplement the spring influx of new fry.
Like the other wintering ponds already described, these are a series
of trenches and ponds, totalling 4 500 m2 in area in the Shabolatsk
liman. These can be covered over against the cold, and are warmed by
underground water which has a constant temperature of 10°C. At
temperatures above 8"C, the fry can even be given some food such as
bloodworms, Daphnia, Cyclops, and dried Daphnia.
I n Israel, grey mullet fry are caught in the mouths of streams at the
beginning of winter, and are stocked in the fishponds to grow t o
marketable size. They therefore have to be wintered in special ponds
where they may be crowded a t a rate of 25-30 per m2 of pond area.
They are fed, and are able to put on some weight in the winter
storage period (Yashouv, 1966).
I n India, the fry admitted into the ponds in spring may be held
in small ponds within the larger ones until they have grown strong
enough to hold their own in the main ponds. The small fish, both
Chanos and grey mullet, are manipulated about the ponds by using
their strong instinct to swim against a current.
I n the culture of the " sugpo )' prawn in the Philippines, the use of
fresh water in which to grow the young has been found more favourable
during the earlier stages, but in the later stages brackish or salt water
gives the better rate of growth (Caces-Borja and Rasalan, 1967).
" Sugpo '' fry, when newly stocked in a pond, tend to remain where
they are liberated, no doubt as a feature of their known habit of
clinging to a substrate. So in practice, the fry are widely and evenly
distributed in the pond, so as to be less vulnerable to predators than
if they remain crowded together.
163
brackish water (Fig. 11). The young fish stay long enough in the
trenches to become accustomed to the climate of the valli. When strong
enough, they are free (as in the Chanos wintering ponds) to swim out
into the main growing pond.
I n the Russian limans, the first grey mullet fry to ascend the channels from the sea to the lagoon are those of the golden grey mullet,
Liza aurata, and these may be caught by lift-nets or seines to be
counted. Any surplus may be sold while, if there is a deficit, more fry
may have to be bought (Zambribortch, 1962; Ilin, 1954). Later in the
season, the ascending fry include a proportion of Mugil cephalus and
M . saliens, and these late migrants will not have had time to grow to
a commercially acceptable size by winter. Zambribortch thinks that
inadequate stocking with fry is one of the chief reasons for the poor
performance of the limans as fish farms, and he describes wintering
ponds in which these late arrivals can be kept alive, and so be available
to supplement the spring influx of new fry.
Like the other wintering ponds already described, these are a series
of trenches and ponds, totalling 4 500 m2 in area in the Shabolatsk
liman. These can be covered over against the cold, and are warmed by
underground water which has a constant temperature of 10°C. At
temperatures above 8"C, the fry can even be given some food such as
bloodworms, Daphnia, Cyclops, and dried Daphnia.
I n Israel, grey mullet fry are caught in the mouths of streams at the
beginning of winter, and are stocked in the fishponds to grow t o
marketable size. They therefore have to be wintered in special ponds
where they may be crowded a t a rate of 25-30 per m2 of pond area.
They are fed, and are able to put on some weight in the winter
storage period (Yashouv, 1966).
I n India, the fry admitted into the ponds in spring may be held
in small ponds within the larger ones until they have grown strong
enough to hold their own in the main ponds. The small fish, both
Chanos and grey mullet, are manipulated about the ponds by using
their strong instinct to swim against a current.
I n the culture of the " sugpo )' prawn in the Philippines, the use of
fresh water in which to grow the young has been found more favourable
during the earlier stages, but in the later stages brackish or salt water
gives the better rate of growth (Caces-Borja and Rasalan, 1967).
" Sugpo '' fry, when newly stocked in a pond, tend to remain where
they are liberated, no doubt as a feature of their known habit of
clinging to a substrate. So in practice, the fry are widely and evenly
distributed in the pond, so as to be less vulnerable to predators than
if they remain crowded together.