Английский язык: Сборник текстов и упражнений для студентов специальностей "Промышленное рыболовство". Дьякова Н.П. - 64 стр.

Eggs of trout, salmon and catfish are relatively large and resilient, so high water flow
rates are tolerated. The eggs of many species, however, tend to be susceptible to me-
chanical damage, so care must be taken to provide a calm environment to prevent the
eggs from bumping into each other or into the walls of culture tanks. Various marine
fishes fall into the latter category, as do many invertebrates. At the same time, some
exchange of water is required to dilute waste products like ammonia which are pro-
duced by developing eggs and larvae.
Some eggs hatch into larvae within 24-48 hours after fertilization, while others may
require several weeks or even months of incubation. Generally, warm water species
develop and hatch quickly, while coldwater species require considerable time periods
for development.

                                  World supplement

      fall                                     осень
      to broadcast                             разбрасывать, распространять
      to fertilize                             зд. оплодотворять
      to hatch                                 выклевываться
      nekton                                   нектон
      scenario                                 сценарий
      adhesive                                 клейкий
      fry                                      молек
      gravel bottom                            дно из гравия
      to replicate                             повторять, копировать
      to induce                                вызывать


                                   ТЕХТ 22
                           DISEASES AND PARASITES

Like other organisms, aquaculture species are susceptible to a broad array of diseases
and parasites such as viruses, bacteria, parasitic protozoans, helminths (worms),
copepods and others. When a disease or parasite outbreak occurs in a population of
aquatic organisms, it is known not as an epidemic (a term used for the same problem
in human populations) but as an epizootic. In most instances, epizootics only result
after a population has been stressed.
Stress can occur in a number of ways. If water quality deteriorates, even for a short
period, the animals exposed to that water will undergo stress. Handling is another
cause of stress in aquaculture species, as are overfeeding or sustained underfeeding.
Following exposure to a stressful situation, an epizootic may occur within as little as
24 hours or as long as 2 weeks. The period between the stress episode and the onset
of disease or parasite infestations depends on the time involved in building the num-
bers of disease and parasitic organisms to a high enough level that signs of the dis-

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