74
J. E. SHELBOURNE
Because of the migratory habits of fish and the difficulties experienced in stocking his enriched lochs with young transplants, Gross
w w unable to establish one of his main objectives-the relationship
between the quantity of fertilizer added and the yield of fish. There
is a very strong case indeed for repeating this classical work, once a
large-scale plaice-rearing technique has been developed. Such a scheme,
involving an increase in basic fertility, would provide an excellent
opportunity for pioneering true marine fish-farming methods. Small
plaice released into enriched areas would get 5 " flying start " during
their first year of life. With the onset of winter, the usual emigration
to deeper offshore grounds would clear the loch in preparation for the
next season's restocking programme.
Fast growth during early life leaves its mark on the otolith ; Gross
was able to distinguish between nursery stock and slow-growing fish
outside the loch. Fast-growing transplants had wider otolith rings and
stronger marginal incisions and indentations. With this '' built-in "
marking device, it should be a comparatively simple matter to pick
out loch-dwellers from resident stock on offshore winter trawling
grounds, and, by adequate trawl surveys, to assess the results of nursery-ground developmeat in economic terms.
The use of sea-loch8 for marketable fish production could conceivably be taken a stage further by completing their enclosure with
fish screens or sluice gates, and, if necessary, providing a mechanical
method of controlled water renewal. The market price of sea-caught
fish will largely determine the credibility of fish farming schemes in
this country; there may well come a time when a farmed product
could compete with, and be complementary to, the hunted stock.
C. Pond culture of jlatjbh
As another step in the direction of marine fish culture and domestiaation, we intend to explore the possibility of following up the present
fish-rearing project with a further fattening programme in shore ponds.
These ponds or channels could be sited to receive the warm outflow
from coastal atomic power stations, some of which are discharging
as much as 50 million gall of sea water/h, at 7-8"C above intake temperature. The overall growth rate of commercial species in our coastal
waters is comparatively slow, due to food scarcity and low water
temperature in the winter. Gross (I960b) was able to increase the
growth rate of flounders and plaice three or four times, in terms of
weight, merely by providing an abundance of food. If temperature
could be maintained at an optimum for growth during the whole year,
J. E. SHELBOURNE
Because of the migratory habits of fish and the difficulties experienced in stocking his enriched lochs with young transplants, Gross
w w unable to establish one of his main objectives-the relationship
between the quantity of fertilizer added and the yield of fish. There
is a very strong case indeed for repeating this classical work, once a
large-scale plaice-rearing technique has been developed. Such a scheme,
involving an increase in basic fertility, would provide an excellent
opportunity for pioneering true marine fish-farming methods. Small
plaice released into enriched areas would get 5 " flying start " during
their first year of life. With the onset of winter, the usual emigration
to deeper offshore grounds would clear the loch in preparation for the
next season's restocking programme.
Fast growth during early life leaves its mark on the otolith ; Gross
was able to distinguish between nursery stock and slow-growing fish
outside the loch. Fast-growing transplants had wider otolith rings and
stronger marginal incisions and indentations. With this '' built-in "
marking device, it should be a comparatively simple matter to pick
out loch-dwellers from resident stock on offshore winter trawling
grounds, and, by adequate trawl surveys, to assess the results of nursery-ground developmeat in economic terms.
The use of sea-loch8 for marketable fish production could conceivably be taken a stage further by completing their enclosure with
fish screens or sluice gates, and, if necessary, providing a mechanical
method of controlled water renewal. The market price of sea-caught
fish will largely determine the credibility of fish farming schemes in
this country; there may well come a time when a farmed product
could compete with, and be complementary to, the hunted stock.
C. Pond culture of jlatjbh
As another step in the direction of marine fish culture and domestiaation, we intend to explore the possibility of following up the present
fish-rearing project with a further fattening programme in shore ponds.
These ponds or channels could be sited to receive the warm outflow
from coastal atomic power stations, some of which are discharging
as much as 50 million gall of sea water/h, at 7-8"C above intake temperature. The overall growth rate of commercial species in our coastal
waters is comparatively slow, due to food scarcity and low water
temperature in the winter. Gross (I960b) was able to increase the
growth rate of flounders and plaice three or four times, in terms of
weight, merely by providing an abundance of food. If temperature
could be maintained at an optimum for growth during the whole year,