56
The Last Resource
pasture. All that was needed to complete the picture was a supply of
young sh.
In 1952 james Shelbourne and his co-workers at the British
Ministry of Agriculture, Fisheries and Food’s laboratories in
Lowestoft began looking into this very problem. Their main concern
was to raise atsh, such as plaice and sole, from eggs and beyond
the stage of metamorphosis. At metamorphosis the larval plaice
undergoes a singular change: the right side of its body becomes
pigmented, the left eye migrates slowly across to this coloured side
and the body becomes attened. At the end of the process one is left
With a miniature adult about the size of a thumb-nail. After metamorphosis in the open sea the growing plaice changes its habits as
well as its appearance. lt forsakes the surface waters—and the most
dangerous period of its existence—to take up life on the sea oor
where its natural camouage helps it to avoid undesirable attention
from potential predators. In other words, survival beyond metamor—
phosis is the key to success. If the young sh have to be released
before this stage they are hardly better off than the very young
larvae in the earlier hatehery experiments.
Working in laboratories at Lowestoft and Port Erin on the Isle of
Man, the British scientists systematically investigated the con—
ditions essential to successful rearing. They ‘juggled’ with various
factors of the environment such as light intensity and temperature,
but for some reason survival of sh was below 30 per
cent of the
initial eggs. Then they tracked down the cause of the trouble——
marine bacteria. Conditions in the rearing tanks were ideal for
microbes which settled on the eggs, either killing the growing
embryos or so seriously weakening them with toxic substances that
few larvae survived long after hatching. In spring 1962, Shelbourne
added a mixture of antibiotics—penicillin and streptomycin—to the
water circulating through the tanks. The results were spectacular,
with over 65 per cent of the sh surviving to metamorphosis. The
scene was set for a further expansion of the work and with the help
of the British White Fish Authority a pilot scale hatehery was
established at Port Erin.
Adult plaice and sole, living in two large sea—water ponds adjacent
to the hatchery, supply the eggs which are scooped from the surface
during the spawning season (from mid—February to May) and
transferred to rearing tanks stacked in racks in the hatchery. Since a
female plaice may produce up to roo,ooo eggs or more, there is no
The Last Resource
pasture. All that was needed to complete the picture was a supply of
young sh.
In 1952 james Shelbourne and his co-workers at the British
Ministry of Agriculture, Fisheries and Food’s laboratories in
Lowestoft began looking into this very problem. Their main concern
was to raise atsh, such as plaice and sole, from eggs and beyond
the stage of metamorphosis. At metamorphosis the larval plaice
undergoes a singular change: the right side of its body becomes
pigmented, the left eye migrates slowly across to this coloured side
and the body becomes attened. At the end of the process one is left
With a miniature adult about the size of a thumb-nail. After metamorphosis in the open sea the growing plaice changes its habits as
well as its appearance. lt forsakes the surface waters—and the most
dangerous period of its existence—to take up life on the sea oor
where its natural camouage helps it to avoid undesirable attention
from potential predators. In other words, survival beyond metamor—
phosis is the key to success. If the young sh have to be released
before this stage they are hardly better off than the very young
larvae in the earlier hatehery experiments.
Working in laboratories at Lowestoft and Port Erin on the Isle of
Man, the British scientists systematically investigated the con—
ditions essential to successful rearing. They ‘juggled’ with various
factors of the environment such as light intensity and temperature,
but for some reason survival of sh was below 30 per
cent of the
initial eggs. Then they tracked down the cause of the trouble——
marine bacteria. Conditions in the rearing tanks were ideal for
microbes which settled on the eggs, either killing the growing
embryos or so seriously weakening them with toxic substances that
few larvae survived long after hatching. In spring 1962, Shelbourne
added a mixture of antibiotics—penicillin and streptomycin—to the
water circulating through the tanks. The results were spectacular,
with over 65 per cent of the sh surviving to metamorphosis. The
scene was set for a further expansion of the work and with the help
of the British White Fish Authority a pilot scale hatehery was
established at Port Erin.
Adult plaice and sole, living in two large sea—water ponds adjacent
to the hatchery, supply the eggs which are scooped from the surface
during the spawning season (from mid—February to May) and
transferred to rearing tanks stacked in racks in the hatchery. Since a
female plaice may produce up to roo,ooo eggs or more, there is no