Vocabulary

dengue fever	лихорадка денге
minnows	мелкие галаксиевые рыбки
bait	приманка, наживка

Answer the questions

1. What is the main aim of aquaculture?

2. What are additional purposes of aquaculture?

3. What are the other purposes for which aquatic organisms grown?

5 Criteria for commercially successful aquaculture

The twentieth century witnessed the science of fish culture unveiling many new methods for growing aquatic animals and plants.

Although hatcheries serve a wide range of purposes, many cultivate fish species are grown to supplement recreational fishing. This freshwater hatchery in Indiana supports the state's stocking strategy, and annually cultivates about 30 million walleye eggs. Eggs change in color from bright yellow to black as the fry develop and hatch inside incubating cylinders.

Reproduction of desired species, feed formulation, and water quality management have helped to generate the rapid growth of aquaculture. The biological selection of culture species depends on many factors. A few criteria that must be considered in choosing a species to cultivate include the following characteristics of a species:

• Growth rate;

• Place in the food chain;

• Climate and environmental adaptations;

• Disease resistance;

• Breeding characteristics;

• Compatibility with other fish species in cultivation; and

• Conversion efficiency (feed-to-flesh).

For example, aquaculturists prefer fast-growing planktivores because of their short food chain.

Interestingly, biotechnological selection criteria are not always the most critical; for example, growing fish unsuitable for local or export markets can readily drive a farmer out of business. Thus, consumer preference, market conditions, regulations against nonnative species, and other economic, social, and political criteria play an important role in species selection.

Vocabulary

recreational fishing	развлекательное рыболовство (платная рыбалка)
walleye eggs	икра светлоперого судака
feed-to-flesh	откорм
planktivores	планктоноядные

Topics for discussion

1. Speak about the main criteria in choosing a species to cultivate.

2. Speak about the other criteria in species selection.

6 Control over reared species Part 1

The large-scale hatchery programs that exist in the various states and provinces of North America and throughout the world produce fishes for release into streams, lakes, reservoirs and the marine environment to enhance commercial and recreational fisheries as well as to repopulate water bodies with endangered and threatened species.

Aquatic plants are also produced for human consumption. In the Orient, for example, seeweed production (e.g. red and brown algae) involves the labour of several hundreds thousands of people. The seaweeds may be consumed directly by man or extracts may be obtained that become components of a variety of substances each of us uses every day. Ice cream, toothpaste, cosmetics and a wide range of other house hold items contain extracts from seaweeds. Some of their businesses are very large, and they are legitimate aquaculture enterprises.

Under natural conditions, as much as 100 pounds per acre of fish might be produced in a lake within a year. Aquaculture systems, by contract, can produce several thousand to even a million pounds per acre in a year.