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Text 26
CULTURE SYSTEMS
Ponds:
The primary culture system used in the world today is the earthen pond. A typ-
ical pond is about 3 feet (1m) deep at the upper end and 6 feet (2 m) deep at the
drain. The bottom and sides are made from compacted earth sides slope at a ration
of 2:1 or 3:1. Steeper slopes make entry and exit from the pond difficult and pro-
mote erosion of the banks, while shallower slopes promote the establishment of
aquatic weeds. Pond size varies greatly-some are only a few square yards (square
meters) in area, but most are an acre (0,4 ha) or larger. Management and harvest-
ing become difficult if a pond is too large, so most culture ponds do not exceed
about 20 acres (8 ha). A well designed pond should have a drain that allows the
water to be completely removed within a day or two and should be provided with
an inflow pipe of sufficient size that the pond can be filled within a reasonable pe-
riod of time. Ponds can be stocked at various densities. If water is exchanged con-
tinuously or frequently, higher densities of culture animals can be maintained than
when static conditions are employed. Catfish farmers in Mississippi are annually
producing over 4,000 pounds per acre (kg/ha) in ponds.
Raceways:
Raceways are linear channels or circular tanks through which water conti-
nuously flows at a rate that will provide a minimum of several exchanges each
day. Raceways are commonly used in hatcheries for the rearing of young animals
and are employed by the trout industry for production from fry to harvest size. In
ponds, fish are exposed continuously to the same water during the growing pe-
riod, while in raceways, the water may be exchanged completely every several
minutes to every few hours.
Cages and Net-Pens:
Culture cages and net pens are structures placed in a natural environment and
stocked with fish for growout. The only real difference between the two is size.
Cages tend to be relatively small (a typical cage has a volume of 1 or 2 m
2
), while
net-pens are often several meters on a side and 10 to 20 meters deep. Cage culture
has been practiced to a limited extent by catfish farmers. For example, in Arkansas
(where leasing of state lakes for cage culture operations is possible ), catfish have
been commercially produced in cages. Cages have also been used by researchers.
Most cage culture is conducted in freshwater environment, while net-pens are most
commonly used in the marine environment. Net pen culture has been restricted to
protected waters, but recently, net pen engineering has advanced to the stage that
open sea pens are now available that can withstand storms without damage.
Vocabulary
side сторона, бок, край, стенка, зд.: стена
compacted плотный, массивный, сжатый
slope уклон
72
Text 26
CULTURE SYSTEMS
Ponds:
The primary culture system used in the world today is the earthen pond. A typ-
ical pond is about 3 feet (1m) deep at the upper end and 6 feet (2 m) deep at the
drain. The bottom and sides are made from compacted earth sides slope at a ration
of 2:1 or 3:1. Steeper slopes make entry and exit from the pond difficult and pro-
mote erosion of the banks, while shallower slopes promote the establishment of
aquatic weeds. Pond size varies greatly-some are only a few square yards (square
meters) in area, but most are an acre (0,4 ha) or larger. Management and harvest-
ing become difficult if a pond is too large, so most culture ponds do not exceed
about 20 acres (8 ha). A well designed pond should have a drain that allows the
water to be completely removed within a day or two and should be provided with
an inflow pipe of sufficient size that the pond can be filled within a reasonable pe-
riod of time. Ponds can be stocked at various densities. If water is exchanged con-
tinuously or frequently, higher densities of culture animals can be maintained than
when static conditions are employed. Catfish farmers in Mississippi are annually
producing over 4,000 pounds per acre (kg/ha) in ponds.
Raceways:
Raceways are linear channels or circular tanks through which water conti-
nuously flows at a rate that will provide a minimum of several exchanges each
day. Raceways are commonly used in hatcheries for the rearing of young animals
and are employed by the trout industry for production from fry to harvest size. In
ponds, fish are exposed continuously to the same water during the growing pe-
riod, while in raceways, the water may be exchanged completely every several
minutes to every few hours.
Cages and Net-Pens:
Culture cages and net pens are structures placed in a natural environment and
stocked with fish for growout. The only real difference between the two is size.
Cages tend to be relatively small (a typical cage has a volume of 1 or 2 m2), while
net-pens are often several meters on a side and 10 to 20 meters deep. Cage culture
has been practiced to a limited extent by catfish farmers. For example, in Arkansas
(where leasing of state lakes for cage culture operations is possible ), catfish have
been commercially produced in cages. Cages have also been used by researchers.
Most cage culture is conducted in freshwater environment, while net-pens are most
commonly used in the marine environment. Net pen culture has been restricted to
protected waters, but recently, net pen engineering has advanced to the stage that
open sea pens are now available that can withstand storms without damage.
Vocabulary
side сторона, бок, край, стенка, зд.: стена
compacted плотный, массивный, сжатый
slope уклон
72
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