384
C. B. COWEY AND J. R. SARGENT
cultivation of one sort or another has been carried on since ancient
times, closer examination reveals that important issues may be
involved. Thus, those fish which have been cultivated for many
generations, e.g. the carp, are vegetarians, as are very many of man’s
domesticated animals. Most fish are carnivorous, especially in the
marine environment, where they are sited at the head of a chain
stemming from phytoplankton through zooplankton to fish. Therefore
the natural diet of marine fish is very rich in protein. To produce
food protein from cheap sources, via an animal normally accustomed
to a diet containing high levels of high quality protein represents a
formidable challenge. This, together with an apparent abundance of
fish from natural sources, may be the reason why up to about 1940
there was little apparent awareness of, or concern with, many of the
facets of fish farming, i.e. nutrition, disease, selective breeding,
pathology, water quality and so on. The awakening of interest in
these matters reflects to some extent our present concern with the world
supply of food protein, of which the concern of fishery scientists for
the conservation of natural fish stocks is a further aspect. It is against
such a background that research in fish cultivation has flourished.
In addition, experimental studies on the nutritional problems posed
to fish will certainly help to define the food requirements of natural
populations, thus furthering our understanding of the natural food
chain and the complex balance between species and the aquatic
environment.
Estimates of present annual world production of marine and freshwater fin fish by farming methods amount to about three million
metric tons with a further million tons of shellfish (Richardson, 1970).
It is currently estimated that by 1985 fish farming w i l l expand to an
annual production of the order of twenty million tons.
Among the characteristics which Bardach (1 968) considers desirable
in an aquatic animal for productive husbandry are (i) they should
breed in captivity so as to make selective breeding possible, (ii) the
eggs or larvae should be hardy enough to survive rearing under controlled conditions, (iii) larvae should accept artificial food or have food
habits that can be met by operations which increase their natural food,
(iv) they should grow rapidly on abundantly available food that can be
supplied cheaply.
The scope which exists for expansion of farmed fish in favourable
environments is best shown by reference to the channel catfish
industry in the U.S.A. In 1963 about 17 000 acres were under intensive
warm-water cultivation of which 2 370 acres were catfish. By 1969,
68 000 acres in the U.S.A. were under intensive warm-water fish culti-
C. B. COWEY AND J. R. SARGENT
cultivation of one sort or another has been carried on since ancient
times, closer examination reveals that important issues may be
involved. Thus, those fish which have been cultivated for many
generations, e.g. the carp, are vegetarians, as are very many of man’s
domesticated animals. Most fish are carnivorous, especially in the
marine environment, where they are sited at the head of a chain
stemming from phytoplankton through zooplankton to fish. Therefore
the natural diet of marine fish is very rich in protein. To produce
food protein from cheap sources, via an animal normally accustomed
to a diet containing high levels of high quality protein represents a
formidable challenge. This, together with an apparent abundance of
fish from natural sources, may be the reason why up to about 1940
there was little apparent awareness of, or concern with, many of the
facets of fish farming, i.e. nutrition, disease, selective breeding,
pathology, water quality and so on. The awakening of interest in
these matters reflects to some extent our present concern with the world
supply of food protein, of which the concern of fishery scientists for
the conservation of natural fish stocks is a further aspect. It is against
such a background that research in fish cultivation has flourished.
In addition, experimental studies on the nutritional problems posed
to fish will certainly help to define the food requirements of natural
populations, thus furthering our understanding of the natural food
chain and the complex balance between species and the aquatic
environment.
Estimates of present annual world production of marine and freshwater fin fish by farming methods amount to about three million
metric tons with a further million tons of shellfish (Richardson, 1970).
It is currently estimated that by 1985 fish farming w i l l expand to an
annual production of the order of twenty million tons.
Among the characteristics which Bardach (1 968) considers desirable
in an aquatic animal for productive husbandry are (i) they should
breed in captivity so as to make selective breeding possible, (ii) the
eggs or larvae should be hardy enough to survive rearing under controlled conditions, (iii) larvae should accept artificial food or have food
habits that can be met by operations which increase their natural food,
(iv) they should grow rapidly on abundantly available food that can be
supplied cheaply.
The scope which exists for expansion of farmed fish in favourable
environments is best shown by reference to the channel catfish
industry in the U.S.A. In 1963 about 17 000 acres were under intensive
warm-water cultivation of which 2 370 acres were catfish. By 1969,
68 000 acres in the U.S.A. were under intensive warm-water fish culti-