ESTUARINE FISH FARMING
183
FIG. 11. View across an Italian brackish-water fish farm (valle). Over-wintering ponds
sheltered by trees, in foreground; main pond in background. Note low water-level
in main pond due to summer evaporation. (Photo : Professor L. 8. Beadle.)
During the rest of May and June, the sluice gates are kept closed,
and are only opened at high water if the water-level within the pond
falls too much through evaporation. I n July and August, when
evaporation is intense, sea water may be admitted, or fresh water
from the canals, until the water temperature begins to fall in September.
The water in the ponds should now have a high salinity, and its IeveI
be low through evaporation (Fig. 11, taken in August). This ensures
that when fishing begins, a strong flow of water will enter the pond
through the main sluice, in which are placed the fishing traps.
183
FIG. 11. View across an Italian brackish-water fish farm (valle). Over-wintering ponds
sheltered by trees, in foreground; main pond in background. Note low water-level
in main pond due to summer evaporation. (Photo : Professor L. 8. Beadle.)
During the rest of May and June, the sluice gates are kept closed,
and are only opened at high water if the water-level within the pond
falls too much through evaporation. I n July and August, when
evaporation is intense, sea water may be admitted, or fresh water
from the canals, until the water temperature begins to fall in September.
The water in the ponds should now have a high salinity, and its IeveI
be low through evaporation (Fig. 11, taken in August). This ensures
that when fishing begins, a strong flow of water will enter the pond
through the main sluice, in which are placed the fishing traps.