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4. UTILIZATION


Though sharks make up only a small percentage of the species targeted by the world's fisheries, they are extremely versatile and humans can use much of the carcass. Meat and fins have been traditionally eaten but also skin and internal organs are often used for food. Shark fins have become one of the world’s most lucrative fisheries’ commodities, particularly appreciated in Chinese cuisine. Shark cartilage has been claimed to be beneficial in a great variety of diseases, such as arthritis, psoriasis colitis, acne, enteritis, phlebitis, rheumatism, peptic ulcers, haemorrhoids, herpes simplex, melanoma, recently also AIDS, and above all cancer. Even though its benefits are unproved, a new market for shark cartilage as an alternative therapy for cancer treatment and prevention has been created. Sharks are also valued for their liver oils, specially the hexaunsaturated isoprenoid alkene squalene. Interest in shark liver oil dates back hundreds of years. In the 18th and 19th century, it was used for lighting. Before and during the Second World War, shark livers were in demand for their rich stores of Vitamin A. Since then Vitamin A from shark liver oil has been largely replaced by the synthetic product. Nowadays liver oil is mainly used in the textile and tanning industries and in the production of cosmetics, pharmaceutical products, and lubricants. The skins can be manufactured to produce high-quality leather or used as an abrasive. Discards are also used for the production of fishmeal and fertilizer. In addition shark teeth and jaws are marketed and sold. The composition and weight of sharks vary considerably between species as can be seen in the following table.

Table 5 Weight composition of some shark species

Species

Ratio of body parts, percentages

Trunk

Fillet

Head

Viscera*

Liver

Bones

Fins

Skin

Horn

33.6

20.8

38.6

15.6

5.2

5.8

11.2

9.6

Sevengill

52.0

35.0

29.0

13.7

4.4

6.8

5.0

9.8

Salmon

-

-

-

-

12.0

-

-

-

Thresher

-

-

-

-

10.0

-

-

-

Lesser spotted dogfish

36.6

-

20.0

39.2

6.6

-

4.1

-

Korothokhvostaya

56.4

45.5

22.2

18.7

7.9

3.3

5.4

7.5

Krivozubaya

61.0

51.0

21.8

10.6

2.7

4.8

5.8

5.0

Vysokoperaya

48.4

40.0

31.6

12.6

4.2

3.2

5.8

5.3

Copper

41.8

35.4

26.5

26.6

12.7

2.2

5.1

4.2

Blacktip

67.3

56.0

19.3

13.2

3.1

2.6

1.5

7.2

Kosyachnaya

53.1

49.6

21.0

20.8

9.5

4.1

5.1

5.1

Soupfin)

44.7

-

14.9

35.7

2.9

-

4.5

-

Whitetip

50.1

37.2

30.4

12.7

7.3

3.6

6.4

8.4

Dinnorukaya

55.8

45.5

27.2

10.6

5.3

3.2

6.7

5.8

Smooth-hound

60.8

45.9

22.0

13.0

2.7

9.4

4.5

5.4

Blue

54.6

40.2

21.3

12.2

4.4

-

6.0

12.0

Hammerhead

62.0

54.4

18.3

13.7

5.5

3.4

5.3

4.2

Kitefin

33.3

23.0

17.1

46.1

19.2

3.0

2.5

7.3

Silky

61.2

52.3

21.3

9.2

2.9

3.9

4.8

4.9

Tiger

47.6

36.2

21.3

28.1

17.5

3.0

4.9

8.0

* Including the liver
Source: Gordievskaya, Shark flesh in the food industry, 1973.

If in theory each part of most sharks can be used, in practice it is extremely problematic to obtain all the different products from one animal, as not all sharks are appropriate due to size and biological features. It is also impossible to produce at the same time good quality meat in fresh or frozen form and leather from the same shark. The processors have to decide in advance which will be the major product, meat or hides. Good quality meat can only be obtained if the shark has been appropriately handled after it is caught. It has to be immediately bled, dressed and iced to prevent urea from contaminating the meat, but the exposure to fresh water or to ice usually damages shark skins. At the same time sharks cannot be iced before being skinned, and meat of such sharks is not suitable for frozen products. Another important reason for the partial processing of caught sharks is also the actual market value of the different products. Often only the most valuable parts are used and processed, such as fins and, nowadays, also cartilage, while the rest of the animal is discarded. Fins are nearly always used but not all sharks have fins large enough to obtain high prices. The value of livers is not as high as in the past and moreover valuable livers are found only in a restricted number of deepwater sharks.

Sharks do not all have the same commercial value nor can they be used in the same way. Regional preferences need to be taken into consideration; some species are valued in certain countries while they may not be appreciated elsewhere. The table in Appendix II summarises the available information on the use of sharks in different countries.


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