Omega-3 In Arabian Gulf Fish (3)
Shark attacking man is rarely heard of in the Gulf. We probably do not have the species of sharks which attack human in the Gulf. I have never heard or seen a person bitten by a shark over the last five decades in Qatar. I frequently swam with friends in the sea since I was a little boy and on some occasions, I saw peaceful sharks passing by us. But those sharks coming near the shore were no more than two meters long. They were more scared of us than we of them.
Because I lived on seashore cities in the Gulf I enjoyed eating a variety of fish dishes such as baked, grilled, fried, stewed fish, etc. But there is only one main way of cooking shark fish in all the Gulf States to my knowledge. That delicious dish is called "Jisheed" (Fig. 1), which is shredded boiled shark flesh then fried with onion and herbal seasonings. We eat only the small, less than 70 cm long, baby sharks (Fig. 2) but not the adult sharks. The adult sharks are used as fertilizers and oil is extracted from their liver to paint local wooden ships. Unlike the Chinese and Japanese who love shark fin soup and consider it, a delicacy we discard the fins.
It is recommended that only the female shark be used for food but only a few people could tell the difference between a male from a female shark. Shark meat was the Viagra of the old men in the Gulf for centuries. An old Qatari fisherman told me a popular community story: A man brought a baby shark and gave it to his wife to cook. She asked him how he wanted it cooked. He said: “If it is baked, it strengthens the vision; if jisheed it strengthens the male organ.” She said: “No need for baking, your vision is good.” The Chinese have similar shark aphrodisiac myth but in relation to its fins. They also believe that shark's fin strengthens the internal organs and retard aging. Some elderly men in the Gulf still consider shark their traditional Viagra.
Fig. 2 Baby Shark
As far as strengthening the vision, it may not be a myth if part of the liver is also eaten. Treating night blindness with fish liver was an ancient remedy in the Gulf. The ancient Babylonians used sheep liver for that purpose, but in the Gulf, fish liver is used. As a child, I witnessed the successful treatment of my father's night blindness with the fish liver. I used to hold his hand and take him to the mosque at night, but after a week of eating fish liver, he regained his night vision. We now know the reason for that success. Night blindness is caused by vitamin A deficiency. The main dietary source of vitamin A is found in animal and fish liver oil. Shark has a huge liver that constitutes up to 30% of its body mass. Unlike bony fish, sharks do not have gas-filled swim bladders for buoyancy that keeps them afloat. Instead, sharks rely on a large liver, filled with oil for buoyancy.
In the west, there was another therapeutic myth claiming that Sharks do not get cancer and that its cartilage is anti-cancer. So shark cartilage was made as a dietary supplement sold in health food stores. CNN headlined on July 9, 1998: Shark substance holds hope for cancer treatment1. On 6 April 2000 BBC news online reported: Shark cancer claims rubbished. The research was carried out at the Johns Hopkins University and George Washington University in the US refuted that claim. By looking at a registry of tumors in animals, they found 40 cases of tumors in sharks and related animals like skates and rays2.
The sex of a shark can be easily determined. The males have modified pelvic fins which have become a pair of claspers that fulfill the role of the mammalian penis. During copulation, the erectile claspers are bent forward. The male inserts one cartilaginous clasper at a time into the female. To show my cardiology colleagues who may never have the opportunity to examine sharks, I obtained a male and female baby sharks for lunch and photographed their sex organs for illustrations (Fig.3).
Fig.3 The male shark on the right
Sharks may bite for love. During mating, males of many species bite females on the pectoral fins or the middle of the back to hold onto them. Females often bear scars or marks3.
Sharks have a different reproductive strategy from most fish. Instead of producing huge numbers of eggs (survival rate of less than 0.01%), sharks normally produce few pups and some species produce as few as two. These pups are either protected by egg cases or born live. There are three ways in which shark pups are born, depending on the species4:
· Oviparity - They lay eggs.
· Viviparity - These sharks maintain a placental link to the developing young, more analogous to mammalian gestation than that of other fishes. The young are born alive and fully functional.
· Ovoviviparity - Most sharks utilize this method. The young are nourished by the yolk of their egg and by fluids secreted by glands in the walls of the oviduct. The eggs hatch within the oviduct, and the young continue to be nourished by the remnants of the yolk and the oviduct's fluids. The first embryos to hatch eat the remaining eggs in the oviduct. So shark may be the only animal that could be considered 'predator in utero'. The young are born alive also and fully functional.
I read once about a biologist who made an incision in a shark abdomen and inserted his gloved finger in the incision for examination. His finger got bitten by a starving shark fetus in the abdomen.
Most of the shark oil is in its liver which is not considered edible in the Gulf. One source5 claimed that Shark has more fat content than salmon as seen in table1.
Table 1. Shark and Salmon compositions. The substance is in grams per 100 gram of flesh5.
The Qatar Ministry of Public Health (QMH) laboratory analysis of gray dog shark flesh revealed that fatty acid content in mg/100 gram of edible portion contains more ω3 than ω6:
· Total ω3 is 38.2
· Total ω6 is 19.2
· The ratio of ω3/ω6=2
The EPA portion is more than DHA portion of fatty acids: EPA (%) 40.1; DHA (%) 33.2
The edible portion of shark from Qatar waters is poor in ω3 fatty acid. It is worse than the fish I discussed in the last article, the Hamour6. QMH studies showed neither shark nor Hamour (grouper) is as good as Kanad fish (King Mackerel) for fatty acid content in the edible portion as seen in table 2.
Table 2: ω3 Fatty acid content of Hamour Shark, Mackerel and sardines (mg/100g):
Source: Qatar Ministry of Public Health Lab.
It is not surprising to me that Mackerel has a high content of ω3 because Sardines are its main source of food. As could be seen in Table 2, Sardine has a huge amount of ω3 fatty acids, but they are the least popular fish in the Gulf. I use it only as fertilizer for my palm trees. The last time I ate Sardine was many years ago. It was canned Sardine from the USA. I do know a few people in Doha who buy from the supermarket imported canned sardines and canned tuna as a delicacy, while very cheap and fresh sardines and fresh tuna are available in the same store. It may sound strange but that is what I may call a matter of taste.
3. SeaWorld/Busch Gardens Animal Information Database: http://www.buschgardens.org/infobooks/Sharks&Rays/reproduction.html
4. From Wikipedia: http://en.wikipedia.org/wiki/Shark
6. Albinali, H. A. The Omega-3 in Arabian Gulf Fish part 2. Heart Views: 2009;9:(4),165-166.