Английский язык: Сборник текстов и упражнений. Дьякова Н.П. - 61 стр.

culture option may not exist. Commercial aquaculture is not, in general, a means
of providing inexpensive animal protein to the masses. Aquaculture can create
jobs, enhance the overall economy of a region and thereby help to improve the
plight of under pivileged peoples. It is not a panacea, however, and should not be
looked upon as the means to prosperity for large numbers of those who live in the
developing nations of the world.

                                 Word supplement

   subsistence aquaculture                         аквакультура для пропитания
   to enhance                                      повышать
   plight                                          мучительное положение
   under privileged people                         неимущие люди
   prosperity                                      преуспевание



                               Text 22
                     THE BIG TWO IN FISH CULTURE

    The most widely cultured groups of fishes in the world are the carps. While
the people of the USA are most familiar with the common or European species,
carp culture is dominated by production of a variety of Chinese carps including
the common, big head, silver and grass carp. In the USA the common carp was
introduced from Europe during the 19 th century. The Chinese have developed
carp culture to a fine art. They use a system known as polyculture (two or more
non-competing species are reared in the same water system) in which at least four
species of carp are grown in the same pond. Ponds in China are often fertilized
with organic fertilizers which produce plant and animal food for fish. Aqricultural
wastes may also be used. Common carp feed on benthos, silver carp on phytop-
lankton, big head carp on zooplankton and grass carp on rooted aquatic vegeta-
tion. Thus various food supplies are used by various culture species. Stocking
rates are related to the food supplies. In recent years, prepared feeds have become
more common in China, though pelleted diets may still be used in combination
with fertilization. Indian carps (various species) and common carp are more
commonly reared in monoculture (only one species present in the culture system).
Depending on expected production, the ponds may be fertilized, or prepared feeds
may be offered. In Europe and Israel, common carp are maintained at high densi-
ties and are fed pelleted rations that meet their nutritional requirements.
    Carps will spawn naturally in ponds, though hatcheries are often maintained.
Hormones may be injected into the adults to induce spawning. Eggs and milt may
be obtained by manual stripping. The eggs are maintained in a hatchery and the
young fish are stocked into nursery ponds. The system is relatively simple. Carp
are able to tolerate fairly wide ranges in environmental conditions, so the technol-
ogy required for their culture is not highly sophisticated. The second most widely
                                        61