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Production systems for aquaculture




Variant IV

A) is practiced b) practices c) was practiced

Aquaculture ________ for a number of reasons, chief among them is food production and income generation.

A) is caught b) was caught c) had been caught

Developing countries provide around 70 percent of the total world supply of fish for human consumption, much of which _______ using traditional small-scale and labor-intensive technologies.

A) have helped b) helped c) had helped

Advances in controlled reproduction of desired species, feed formulation, and water quality management _________ generate the rapid growth of aquaculture.

A) is harvested b) are harvested c) harvested

The major ocean stocks, which _________ largely by factory fleets, are anchovies (a relatively low-value product), pollock, tuna, herring, and mackerel.

Read the text and translate it

There are only a few production systems in use for aquaculture, and they include earthen ponds, raceways, cages or net pens, and indoor recirculating systems. Earthen ponds or cages placed in existing bodies of water are the oldest production system and the indoor recirculating systems are the newest. For successful culture, considerable technical expertise is required when using a recirculating system. All of the current industries use earthen ponds (catfish, tilapia, Asian carps, shrimp), raceways (rainbow trout), or cages/net pens (Atlantic salmon, yellowtail, an amberjack from Southeast Asia). Producers are experimenting with indoor recirculating systems using a wide variety of species. There are a few successful producers using indoor systems, but the number will inevitably grow as both the systems and information on targeted species increase. Successful aquaculture can be viewed as the correct match of species under a certain set of market conditions with production system. Some species do not tolerate some of the production systems or do not thrive in those systems. Behavioral characteristics of the various species often point toward the appropriate culture systems. For example, sedentary fish (bluegill, catfish, and flounder) should probably be raised in systems without significant water flow (earthen ponds, cages/net pens), whereas those that typically swim a great deal (tuna, trout, and striped bass) can be raised in raceway systems with a constant flow of water.

Fish are generally considered good quality food for human consumption because of the low saturated fat levels and generally high levels of n-3 fatty acids. Fish tend to retain the fatty acids that are in their diet. Thus, we can manipulate the fatty acid concentrations of fish and produce "designer fish" for targeted markets. Further, we can control the fat concentration in muscle through selected feed and produce a low-fat or high-fat fish depending on the demands of the market. Cultured aquatic animals can be safer products for consumption than wild fish because they are raised in a defined environment, and pollutants can be eliminated. Wild fish can be exposed to environmental pollutants and retain those they encounter. Organoleptic properties (taste) of fish and shell-fish raised in aquaculture can be quite different from wild stocks. Fish flavor can be manipulated by dietary ingredients fed to the target species. There is also a taste consideration with environment. Some species can survive both fresh-and saltwater, but osmoregulation changes to meet the challenges of those environments. This physiological change affects taste because of the chemical compounds used to regulate ionic balance. A good example of this is the freshwater shrimp. When raised in freshwater, taste has been described as mild, whereas if the shrimp is placed in saltwater for one to two weeks, it will taste more like a marine shrimp. Even with these positive attributes, aquaculture is experiencing growing pains.

 

Read the text again and answer the questions

1. What are the basic production systems used for aquaculture?

2. When is aquaculture successful?

3. Why is fish useful for human consumption?

Are these sentences true or false?

1. People can not change the fatty acid concentrations of fish.

2. Some species of fish can be raised without large water flow.

3. Not all species can survive in saltwater.

 




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