Physical properties of fish
Shape.The following are the main body shapes of fish:
Torpedo(or spindle) shaped – the body is fusiform, thick at the head, tapering off strongly toward the tail and slightly flattened at the sides (dogfish, saury, garfish, tunny, salmon, cod, herring).
Arrow-shaped, elongated, of equal cross-section, with dorsal and anal fins set far back (pike, saury, garfish).
Flat – markedly flattened at the sides or on top the fish are correspondingly, either narrow, with a large vertical section (bream, plaice) or, on the contrary, broad a very small vertical section (skate).
Snakelike – very long, round, slightly flattened sides, and undulating in motion (eels, lampreys).
Size. The size of fish is determined either by length or by mass (weight). In the fishing industry and trade, it is usual to measure length from the tip of the snout to the beginning of the median rays of the tail fin. Sometimes, however, fish are measured for overall (absolute) length, i. e.: from the tip of the snout to the centre of a straight line linking the ends of the outer rays of the tail. With fish of equal age and length the females are usually heavier than the males. Seasonal variations in size are expressed in an increase in volume and weight, and decrease in both volume and weight after spawning. The growth rate of fish depends on the food available in water, so that the fish of the same age and species caught in different waters vary in weight and length.
The specific weight of a fish is the ratio of its weight to volume (in grammes per cubic centimetre).
The bulk weight of fish is their weight in kilograms (or metric tons) per unit volume (cubic metre). This factor must be taken into account when calculating capacity for storage and salting, or calculating transport requirements at packaging. The centre of gravity of a fish is near the head. In free fall or in sliding down a slope (on a conveyer) fish will therefore always settle head forward in the direction of motion.
Textureorconsistency is the most important in estimating the quality of fish and in determining the cutting effort required. Consistency is gauged by the firmness of the flesh, which increases at first after death reaching its highest value during rigor mortis. Once this stage has passed and fish has been stored for some time its firmness will decrease.
Exercise 4. Find the Russian equivalents for the following:
the median rays, the firmness of the flesh, per unit volume, estimating the quality of fish, volume and weight after spawning, from the tip of the snout to the beginning of the median rays, for storage and salting, calculating transport requirements, the cutting effort, the ratio of its weight to volume, flattened at the sides.
Exercise 5. Find the English equivalents for the following:
должен быть учтен, увеличение объема и веса, доступный корм, центр тяжести, от кончика рыла до хвоста, после нерестования, женская особь, мужская особь, удельный вес, консистенция, срединные лучи хвостового плавника, необходимые усилия при резании, измерять, оценивать, определять, увеличиваться в объеме, уменьшать вес.
Exercise 6. Complete the sentences using information from the text:
1. Seasonal variations in size are expressed in…
2. The centre of gravity of a fish is…
3. Consistency is gauged by…
4. The size of fish is determined either by…
5. Sometimes, however, fish are measured…
6. The growth rate of fish depends on…
7. With fish of equal age and length the females are…
Exercise 7. Fill in the blanks with prepositions after, into, of, by, in, at, on:
1. This factor must be taken … account.
2. Usually we determine the size of fish … length.
3. The firmness … the flesh increases … first … death.
4. The size … fish depends … the food.
5. Variations in size are expressed … decrease … both volume and weight.
Exercise 8. Answer the following questions:
1. What are the main body shapes of fish?
2. What is the difference between torpedo-shaped and arrow-shaped fishes?
3. What are flat fish like?
4. What are the principal characteristics of snakelike fish?
5. How is usually size of fish measured in industry?
6. What are seasonal variations in size expressed in?
7. What does the growth rate depend on?
8. What do we call the specific weight?
9. What do we call the bulk weight?
10. What do we call the centre of gravity of a fish?
11. Why is it important to estimate consistency of fish flesh?
Exercise 9. Speak about a) shape of different species of fish;
b) the size of fish;