1. Choose the equivalents:

Floating feeds; bacterial and fungal growth; to provide nourishment; nutrients will be lost; to trap air within the pellets; raw fish is often used to feed aquacultured species; large algae concentrations; ingredients have been mixed together in proper propor-tions; to use supplemental heat; to pass through a small aperture; most invertebrates are fed prepared feeds; to meet the nutritional requirements; with respect to quality and quantity; to contain animal protein; high (low) carbohydrate level; fat is often

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added in the form of …; waste products from fish processing plants; extended expo-sure to high pressure.

Ингредиенты смешаны вместе в нужных пропорциях; длительное подвергание действию высокого давления; корм находящийся на поверхности (на плаву); продукты отхода с рыборазделочных заводов; использовать дополнительное тепло; часть добавляют жир в виде; рост бактерий и плесени; большинство бес-позвоночных кормят готовым кормом; обеспечивать питанием; содержать жи-вотный протеин; питательные вещества теряются; проходить через небольшое отверстие; задерживать воздух в капсулах; отвечать требованиям питания; в от-ношение количества и качества; часто используют сырую рыбу для кормления искусственно выращиваемых видов; большая концентрация водорослей; высо-кий (низкий) уровень (концентрация) углеводов.

2. Answer the questions:

1. What are carps, oysters, mussels, clams fed on?

2 .What are most fishes and invertebrates of aquaculture fed on? 3. What are usually prepared feeds composed of?

4 .Which proteins do typical aquaculture diets contain?

5 .What is the difference between pressure pellets and extruded pellets or floating pellets?

3. Translate sentences:

1.Известно, что питание и кормление являются важными составляющими в ис-кусственном воспроизводстве различных видов рыб и беспозвоночных. 2.Некоторые виды моллюска такие как устрицы, мидии и двустворчатый мол-люск питаются водорослями и органическими питательными веществами. 3.Карпы, например, питаются фитопланктоном, зоопланктоном, бентосом. Пруды, поэтому часто удобряют органическими удобрениями (навоз скота, сточные воды людей), которые способствуют росту фитопланктона, зоопланк-тона и водных растений. (livestock manure, human sewage).

4.Большинство рыб и беспозвоночных кормят готовым кормом.

5.Готовый корм должен отвечать определенным питательным требованиям и состоять из различных ингредиентов.

6.Обычно, готовый корм содержит животный и растительный белок, углеводы, жиры, витамины и минералы.

7.Готовый корм имеет вид капсулы или шарика.

8.Имеется два вида капсул, те что погружаются на дно и те что находятся на поверхности.

9.Каждый вид капсулы имеет свои преимущества и недостатки.

10. Используя капсулы держащиеся на воде специалист видит, что рыба ест корм и он может контролировать количество предложенного корма и избежать переедания.

11. Эти капсулы могут сохранять питательные вещества в течение 24 часов и более.

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12. Капсулы, погружающиеся на дно могут быстро терять питательные веще-ства, так как они растворяются в течение нескольких минут.

4. Do written translation into Russian.

GENETICS AND REPRODUCTION

If an aquaculturist wants to undertake selective breeding in order to improve the per-formance of the species under culture, it is necessary to have all components of the life cycle under direct control. For some species it has been necessary to obtain young animals for stocking by collecting them in the wild since reliable means of producing young in a hatchery have not been developed. In other cases, wild broodstock are ob-tained because we do not have the knowledge required to grow fish to adult size in captivity or, more often, the cost of growing and maintaining brood fish may be too high. However, for most succeful aquaculture species, the like cycle from egg through adult is controlled by the aquaculturist. Each aquaculture species requires certain conditions for reproduction. Those conditions vary widely. For example, some species spawn in fall or winter, some in spring, and some spawn almost continuously. The key to inducing spawning may be changing temperature (such as falling tempera-tures late in the year or rising temperatures in the spring), increasing or decreasing the amount of daylight present (also known as photoperiod) or a combination of the two. These types of environmental stimule cause changes in the hormone activities within the aquaculture species and lead to the development of eggs and spermand, finally, induce the behavioral activity that accompanies the actual spawning act.

Many aquatic species broadcast their eggs and sperm into water. The fertilized eggs will become members of the plankton community. Upon hatching, the larval animals may continue to swim about in the plankton until they grow sufficiently large to enter the benthos or nekton community. This type of reproductive scenario is typical of shrimp, crabs, lobsters, oysters and certain types of fishes (red drum and striped bass). More specialized reproductive modes are used by many of the species of aquaculture interest. Channel catfish lay eggs in adhesive masses. (about 30.000 eggs). Tilapia males construct shallow nests in pond bottoms into which eggs are deposited and fer-tilized. After fertilization, the female picks up the eggs in her mouth and retains them until after the fry hatch and are able to survive on their own. Trout and salmon lay their eggs in shallow nests (known as redds) constructed in the gravel bottoms of lakes and streams. The newly hatched fish remain in the gravel for a considerable amount of time after hatching. In order to control reproduction in the hatchery envi-ronment, the aquaculturist must understand how the species of interest behaves under natural conditions. Those conditions can be replicated then. In some instances, how-ever, culture environments have been set up to duplicate natural conditions, but the brood animals refuse to spawn. Under those circumstances, hormone injections can be used to induce spawning. Once fertilized eggs are obtained, they need to be incu-bated under the proper conditions (temperature and light may be important, as are dissolved oxygen level and, in the case of marine fishes, salinity, among others).

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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

to broadcast to fertilize to hatch nekton scenario adhesive fry

gravel bottom to replicate

to induce

осень

разбрасывать, распространять зд. оплодотворять выклевываться

нектон сценарий клейкий молек

дно из гравия повторять, копировать 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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ease are observable. Disease and parasite organisms are almost always present in the culture environment, but at very low levels. They only produce disease signs when they are promoted by a lack of resistance in the aquaculture species. An analogy can be drawn in humans. Students in a classroom may be exposed to people with the flu, but not everyone is infected. The immune status of the various individuals plays an important role in who will ultimately show flue symptoms. Students who are stressed (for example, by getting too little sleep) are often much more susceptible than those who are not.

The number of chemicals that can be used to treat disease and parasite problems in aquatic animals is small. Only about 10 compounds have been approved for species that are being reared for direct human consumption. Among them, few are effective at controlling bacteria, some work on a few parasites but not others, and many are themselves toxic if given in improper doses. Some treatment chemicals are effective when added to the water, but some must be ingested by the aquaculture organisms. Animals that are experiencing disease or parasite problems often refuse to eat, mak-ing treatment difficult.

Good overall management of the culture system is perhaps the best way to avoid dis-ease and parasite problems. However, even the best managers experience epizootics on occasion. Treatment chemicals of various kinds should be available, and the cul-turist should know how to use those chemicals. Chemicals such as antibiotics should not be used routinely, but should only be employed when there is a problem requring treatment, or when there is a very strong probability that a disease or parasite epizoo-tic is imminent.