Английский язык: Сборник текстов и упражнений для студентов специальностей "Промышленное рыболовство". Дьякова Н.П. - 55 стр.

исследовательские станции и экспериментальные хозяйства по искусственному
разведению морских беспозвоночных (гребешка, трепанга, устриц) и морских
водорослей (ламинарии, анфельция) созданы в литоральных зонах, преимуще-
ственно в южных. Самая большая станция по разведению ламинарии с площа-
дью 70 гектаров создана в заливе”Posyet” (залив Посвет) бухты Валентина. Там
получают до 70 тон сырой массы в год с одного гектара. Поблизости располо-
жено и экспериментальное хозяйство по выращиванию устриц и гребешка.

                                 World supplement

      Scallop                         гребешок
      Invertebrcetes                  беспозвоночные
      Green material=                 raw material
      Ahnfeltia                       анфельция


                                    TEXT 20
                                CULTURE SYSTEMS

Ponds:
The primary culture system used in the world today is the earthen pond. A typical
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 promote 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 harvesting 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 period of time. Ponds can be stocked at
various densities. If water is exchanged continuously or frequently, higher densities
of culture animals can be maintained than when static conditions are employed. Cat-
fish 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 continuously
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 ex-
posed continuously to the same water during the growing period, while in raceways,
the water may be exchanged completely every several minutes to every few hours.


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