198
C. F. HICKLING
To kill fish lice: 3 p.p.m. of Dipterex in the pond water.
To control flagellates : 2 p.p.m. copper sulphate.
As supplementary food Tang recommends pelleted food to be
given daily at the rate of 1-2% of the biomass of fish.
Finally, as to the manipulation of the stocking, Tang recommends
a start with 7 000 fish per hectare, of which 2 000 will be large fingerlings of 100 g, 2 000 small fingerlings of 40 g, and 3 000 very small
fingerlings of 3 g. This will give a succession of fish to market, and
production can be continued by maintaining the biomass of the fingerlings at 300-800 kglhectare.
Tang estimates that by these measures a natural rate of production
of 200 kglhectarelannum can be increased to 800 by fertilization, to
1 000 by fertilization and pest control, and to 2 000 by stock manipulation.
VII. THE RATE OF FISH PRODUCTION
The rate of production of fish in brackish-water fishponds will
depend on many factors, such as the natural fertility of the soil, the
effect of added fertilizer, of tilling, and of a dry period, on the
culture of the algal felt which is the basis of primary production. It
will also depend on the rate and manner of stocking in relation to the
fertility of the pond, and the rate of survival of the fish stocked.
Finally, it will depend on the amount and composition of the supplementary feeding, if any.
I n intensive systems of fish culture, the whole production of fish
depends on supplementary feeding-the natural production of food by
the environment (even so rich as that of an estuary) playing no part.
I n these cases it is no more justifiable to speak in terms of rate of
production per hectare or per acre per annum than to use these terms
for hens raised intensively in multi-tiered batteries, or swine in intensive fattening pens. Yet they are so used and cause much confusion.
To get a fair figure for production per acre and per annum in such
cases, one would have to calculate the number of acres on which the
food fed intensively was grown, and this would be difficult.
Two examples of intensive fish culture may be given, both from
Japan. I n the culture of the eel, Anguilla japonica, the rate of production, scaled up to terms of per hectare and per annum, is about 13 60026 300 kglhectare. I n the case of the yellowtail, fed intensively on
trash fish, the rate of production is 3 250-7 750 kglhectarelannum.
Onodera (1963) claims that the rate of production of the eel in the
instance quoted is one of the highest recorded, but it is the production
C. F. HICKLING
To kill fish lice: 3 p.p.m. of Dipterex in the pond water.
To control flagellates : 2 p.p.m. copper sulphate.
As supplementary food Tang recommends pelleted food to be
given daily at the rate of 1-2% of the biomass of fish.
Finally, as to the manipulation of the stocking, Tang recommends
a start with 7 000 fish per hectare, of which 2 000 will be large fingerlings of 100 g, 2 000 small fingerlings of 40 g, and 3 000 very small
fingerlings of 3 g. This will give a succession of fish to market, and
production can be continued by maintaining the biomass of the fingerlings at 300-800 kglhectare.
Tang estimates that by these measures a natural rate of production
of 200 kglhectarelannum can be increased to 800 by fertilization, to
1 000 by fertilization and pest control, and to 2 000 by stock manipulation.
VII. THE RATE OF FISH PRODUCTION
The rate of production of fish in brackish-water fishponds will
depend on many factors, such as the natural fertility of the soil, the
effect of added fertilizer, of tilling, and of a dry period, on the
culture of the algal felt which is the basis of primary production. It
will also depend on the rate and manner of stocking in relation to the
fertility of the pond, and the rate of survival of the fish stocked.
Finally, it will depend on the amount and composition of the supplementary feeding, if any.
I n intensive systems of fish culture, the whole production of fish
depends on supplementary feeding-the natural production of food by
the environment (even so rich as that of an estuary) playing no part.
I n these cases it is no more justifiable to speak in terms of rate of
production per hectare or per acre per annum than to use these terms
for hens raised intensively in multi-tiered batteries, or swine in intensive fattening pens. Yet they are so used and cause much confusion.
To get a fair figure for production per acre and per annum in such
cases, one would have to calculate the number of acres on which the
food fed intensively was grown, and this would be difficult.
Two examples of intensive fish culture may be given, both from
Japan. I n the culture of the eel, Anguilla japonica, the rate of production, scaled up to terms of per hectare and per annum, is about 13 60026 300 kglhectare. I n the case of the yellowtail, fed intensively on
trash fish, the rate of production is 3 250-7 750 kglhectarelannum.
Onodera (1963) claims that the rate of production of the eel in the
instance quoted is one of the highest recorded, but it is the production