first appearance datum
126
particular combination of fin rays. Fin clip marks will disappear, usually
within 1 or 2 years, because the fish have the capability to regenerate.
first appearance datum -7biohorizon.
fish -7Pisces.
fish culture the production of fish in an artificial surrounding controlled by
man. Fish can be cultured in: (a) tanks; (b) ponds with either stagnant or
running water, varying with fish species and locality. Pond cultures can yield
3800 to 5000 kg ha- 1 annually); (c) cage-cultures, installed in stagnant water
lakes, in lotic systems (creeks and rivers) or in marine tidal areas (fjords).
The production depends on the fish species and type of cage culture, but
may amount to 350 kg m- 3 annually, as in the case of carp; (d) large enclosures, often divided into compartments by nets. In these culture systems,
productions of up to 4000 kg per ha can be reached. The culture set-ups may
be stocked with larvae or young fish collected in the natural system, or with
brood produced in special hatcheries where fertilized eggs are incubated
and larvae reared to suitable size for stocking in production units. In extensive cultures, fish production depends on the natural food production of the
system, as in the culture of most herbivorous fish (milkfish, mullets). In intensive cultures fish production depends on the additional supply of food for
mostly carnivorous species (salmon, eel, trout). Factors that raise growth rates in
cultured fish above natural levels are optimal temperature and excess food
of optimal composition, but it is most of all the decreased mortality in the controlled environment that leads to the high fish production required to make
fish culture worthwhile. Sometimes fish culture concentrates on rare and
expensive species. -7aquaculture.
fisheries the human activities aimed at catching fish. There are many types of
fisheries, depending on the fish species, the developmental stage of the
human society, and the hydrography and geography of the sea area. A first
distinction is that into fisheries using passive and active catching methods.
Passive are baited angles, long lines, fish traps (as, e.g., lobster pots), but also
drifting nets and fykes, made of netting or wood, and fish traps in rivers.
Active methods range from the simple hunt with arrows and spears, the
enclosing of shallow water with nets, to the fishing with modern trawlers
operating beam trawls, pelagic trawls (-7trawl), Danish seines and purse
seines (-7nets). One of the most peculiar ways of fishing is with trained cormorants wearing neck-rings to prevent them from swallowing the fish they
bring to the small boats of their owners (China, Japan).
fisheries convention convention on fishing and conservation of living resources
of the high seas, signed by 58 countries in Geneva, 1958, and coming into
126
particular combination of fin rays. Fin clip marks will disappear, usually
within 1 or 2 years, because the fish have the capability to regenerate.
first appearance datum -7biohorizon.
fish -7Pisces.
fish culture the production of fish in an artificial surrounding controlled by
man. Fish can be cultured in: (a) tanks; (b) ponds with either stagnant or
running water, varying with fish species and locality. Pond cultures can yield
3800 to 5000 kg ha- 1 annually); (c) cage-cultures, installed in stagnant water
lakes, in lotic systems (creeks and rivers) or in marine tidal areas (fjords).
The production depends on the fish species and type of cage culture, but
may amount to 350 kg m- 3 annually, as in the case of carp; (d) large enclosures, often divided into compartments by nets. In these culture systems,
productions of up to 4000 kg per ha can be reached. The culture set-ups may
be stocked with larvae or young fish collected in the natural system, or with
brood produced in special hatcheries where fertilized eggs are incubated
and larvae reared to suitable size for stocking in production units. In extensive cultures, fish production depends on the natural food production of the
system, as in the culture of most herbivorous fish (milkfish, mullets). In intensive cultures fish production depends on the additional supply of food for
mostly carnivorous species (salmon, eel, trout). Factors that raise growth rates in
cultured fish above natural levels are optimal temperature and excess food
of optimal composition, but it is most of all the decreased mortality in the controlled environment that leads to the high fish production required to make
fish culture worthwhile. Sometimes fish culture concentrates on rare and
expensive species. -7aquaculture.
fisheries the human activities aimed at catching fish. There are many types of
fisheries, depending on the fish species, the developmental stage of the
human society, and the hydrography and geography of the sea area. A first
distinction is that into fisheries using passive and active catching methods.
Passive are baited angles, long lines, fish traps (as, e.g., lobster pots), but also
drifting nets and fykes, made of netting or wood, and fish traps in rivers.
Active methods range from the simple hunt with arrows and spears, the
enclosing of shallow water with nets, to the fishing with modern trawlers
operating beam trawls, pelagic trawls (-7trawl), Danish seines and purse
seines (-7nets). One of the most peculiar ways of fishing is with trained cormorants wearing neck-rings to prevent them from swallowing the fish they
bring to the small boats of their owners (China, Japan).
fisheries convention convention on fishing and conservation of living resources
of the high seas, signed by 58 countries in Geneva, 1958, and coming into