Commercial fish.

Fishing is one of the oldest forms of economic activity of people. Fish for a man — a very valuable source of food (animal proteins and fats), which are easier to digest than vegetable.

Industrial fishing is carried out in the seas, oceans, large rivers, lakes. Fish are grown in specially constructed ponds. Basic ocean space, where year-round fishing, is a subtropical and tropical waters of the Atlantic, Pacific and Indian oceans. These areas of the oceans do not freeze. In areas close to the North pole, the water is cooled, and the Arctic ocean has a permanent ice cover.

Anyone caught in the oceans? Oceanic herring (Atlantic, Pacific), herring, sardine iwashi. These herring are distinguished easily detached scales and gregarious way of life.

In Northern waters catching cod, haddock, saffron cod. These trnkobrani (Fig. 127) can be recognized by the barbels on the chin and three unpaired fins on the back. These fish have long and traditionally fished and loved in Russia.

Fig. 127. Representatives trnkobrani: 1 – cod; 2 – burbot

In the ocean catch and other fish, all familiar names: ocean perch, Alaska Pollock, Grenadier, hake, flounder. Fisheries in the oceans is, as a rule,in places close to the coast, at a depth of 400-500 m. This region of the shelf — coastal ocean shallows at the threshold of transition to greater depths. Here collects a lot of fish. To fish from such depths is designed and gear. In the oceans and seas, fish are caught using trawls, fyke-nets. In our country fish catch in inland seas. For example, small Caspian sprat catches in the Black, Caspian and Azov seas. In the Baltic sea ply Baltic pilchards, or sprats, herring. Traditional in Russia always was fishing on large rivers. Salmon catch in the far East, in Siberia and the European North of our country.

Salmon fish — chum salmon, pink salmon, salmon, sockeye, coho, trout. They can be recognized by the adipose fin on the back. Salmon meat has a wonderful taste, and they give the red caviar.

Like sturgeon, salmon spawn in the upper reaches of the rivers are passable by fish. However, in contrast with sturgeon, salmon are not afraid of the rapids of fast flowing rivers and height differences. Moving to the spawning grounds, they overcome the rapids, small waterfalls and moving against the current towards the fast flowing water.

In the anglers catch and Cypriniformes — carp, silver carp, crucian carp, roach, roach, roach. In addition Cypriniformes in the rivers to catch catfish, pike, perch.

To get a quick and fish products fish are bred in special ponds. In the ponds of fish propagated in specially created conditions: warm, oxygen-rich water and abundant food. To do this, build a system of ponds — feeding, wintering, spawning, rearing (Fig. 128).

Fig. 128. Farms and farming: a —the scheme for the ponds: 1 — river; 2 — the drainage channel; 3 — feeding pond; 4 — wintering ponds; 5 — spawning ponds; 6 — nursery ponds; — carp (1), and species of fish: scaly (2): mirror (3): naked (4)

At different life stages of fish are transferred from one pond to another, third, etc. In breeding ponds carp, carp, carp, carp. In the ponds these herbivorous fish are often hooked a few pike. In the presence of predatory carnivorous fish grow better and faster gain in weight (according to the proverb “a pike lives in the sea that the crucian carp was not asleep”).

Another form of fish farming is the acclimatization of fish. In this way enrich the fish fauna of many areas. Fish are transported in a special water containers in places of acclimatization and release into water bodies. So, from the Black sea to the Caspian moved mullet, salmon and far Eastern salmon in the waters of the Kola Peninsula.

Tasks that people decide in acclimatization, is overcoming the natural barriers of fish sushi, which prevent the settling of fish. It is very important to observe the rule: relocated fish should not become competitors to those who have long lived in this pond.

Many beautiful species of fish people bred in aquariums for aesthetic purposes. These are the breed goldfish (Fig. 129), guppies, gourami, swordtails, angelfish and other thermophilic freshwater species. Contain saltwater fish in the aquarium much more difficult. Home of many aquarium fish — tropical and sub-tropical freshwater reservoirs of South America and Africa. The aquarium hobby is very exciting but important lesson: fish require for their maintenance of constant conditions a certain temperature, light, aeration, purity, and sufficient food.

Fig. 129. Breed goldfish: 1 — telescope, 2 — Valuehost, 3 — livingonlove

Fishing is one of the oldest and most important sectors of the economy. From the fish people get protein foods and fat. Fishery produce in tropical and subtropical waters of the World ocean, inland seas, lakes, large rivers. Because of the over exploitation many species are rare and need protection. Fish bred in fish farms and fish plants. For decorative purposes contain of aquarium fish.

Exercises on the material covered

Using the pictures, name the representatives of commercial fish (see Fig. 128). Tell about their value to humans.

List the names of ponds full of ponds. Explain what is the purpose of each of them?

Any fish bred in fish farms? What is their practical value?

For any fish important rearing in fish farms?

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