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APPENDIX III: NON-FOOD USES OF SHARKS by HOOI KOK KUANG


1 INTRODUCTION

The writer's contract was to update information on the FAO publication entitled Shark Utilization and Marketing by Kreuzer & Ahmed (1978), concentrating on the uses of shark hides, liver oil and teeth, in particular on products which are not used as human food. The report would include pharmaceutical products produced from sharks, but would not reproduce material found in the above-mentioned FAO report.

Over the past 20 years, the recording of catches of sharks has improved only slightly so there is still a great deal of uncertainty about this fishery. The uses to which sharks have been put have changed, and the claims about their health benefits have increased. However, our understanding of these health claims has yet to be fully described.

2 SHARK LIVER OIL PRODUCTS

Kreuzer & Ahmed (1978) reported that the development of synthetic vitamins (particularly vitamin A) led to the virtual collapse of the markets for shark liver oil; it relieved temporarily the fishing pressure on sharks. Shark liver oils have also been used in the textile and tanning industries, as lubricants, in cosmetics and skin healing products, in health products and in traditional foods.

Over the past 20 years, the processing methods for shark liver oils have not changed very much, but quality control techniques have improved the product (Wong, 1998, pers comm) in tandem with related developments, such as refrigeration at sea. However, Summers, Wong & Eyres (undated) also suggested that livers can be ensilaged and stored at ambient temperature instead of more costly refrigeration at sea. They argued that ensiling would not only prevent protein putrefaction and retard oxidation but also aid in the release and recovery of the oil. They considered this was most suited for fisheries located in remote areas. In one of their experiments they found that the highest amount of oil was extracted from samples of liver treated with formic and phosphoric acids and a permitted (food) antioxidant, and the least amount was extracted from a sample left to deteriorate. Rose (1996) observed that in the Maldives, which may possibly be considered as a remote area, the livers are simply left in the sun for hours or days before they are boiled and the oil extracted.

Shark livers have been used traditionally as foods. This ranged from being eaten fresh after its harvesting and cooking, to being preserved by salting and, much later, cooked before eating.

Other uses included the use of crude liver oils to coat the hulls of wooden boats as a preservative against marine fouling, and as fuel for street lamps. Crude liver oils containing squalene were used as lubricants since its melting point is -75oC and its boiling point is 330oC.

There are variations in detail, but the description by Tanikawa (1985) probably covers most of the principles involved in processing the liver for the crude oil. The livers or blubber are chopped or minced before cooking in steam or water. The mixture of oil and water is allowed to cool and settle. The residue may be used in fishmeal production (as in India), or as feed for pigs and poultry. The crude oil is then sent to separating tanks and may be centrifuged (Miwa, 1972). Tanikawa (loc cit) said that after the oil has separated the residue, called "cooked skin of whale", is eaten as a delicacy in the Osaka district of Japan.

Summers, Wong & Eyres (undated) reviewed work on shark liver oils; part of this report appeared in Summers & Wong (1992). They found that squalene, a triterpenoid hydrocarbon and precursor of sterols, was used to manufacture lubricants, pharmaceuticals and bactericides, and as a surface active agent in cosmetics. They reported claims that squalene prevented the formation of nitrosamines in topical products that contain an amine and a nitrosating agent. It was also said to increase skin permeability to topical ointment bases because of its miscibility with human sebum, where it also occurs naturally. Squalene has been used for centuries in many countries in skin creams to soften skin, reduce small facial wrinkles, speed up wound healing, as a moisturiser and as a bactericide (a feature it has in common with other members of the terpenes family). It is often hydrogenated to various extents and used as squalane, which is more stable.

Summers et al investigated seven species of Squalidae that are common to the deep waters of the continental slope surrounding New Zealand; approximately 20% of the body weight was liver. It is believed that the large livers provide buoyancy for these deep- water sharks and contain energy sources adapted to their low oxygen environment. They found that all the livers they investigated contained a large proportion of lipid but the composition of the lipid varied from species to species.

These lipids typically consisted of a mixture of hydrocarbons (mainly squalene, and some pristane), diacyl and mono glyceryl ethers (compounds of fatty alcohols and glycerol by ether linkage) and triglycerides (esters of fatty acids and glycerol).

They used a thin layer evaporator to obtain almost pure squalene with minor levels of lipid oxidation at an operational temperature of 136oC. The purified squalene contained trace amounts of pristane, which is considered a skin irritant. However, when the degummed, bleached, deodorised and partly hydrogenated product was used by laboratory staff for over 6 months, they did not report any skin irritations. In fact they commented that, when used as a base for sunscreen lotion, it had excellent penetration qualities (penetrates the skin at about 2mm/sec), was not greasy (the most desirable feature) and did not develop off-odours.

Current interest in shark oils has focused on their purported effect on health. Anecdotal statements have fuelled the market. Components of shark oils were said to cure certain diseases, relieve pain and improve health generally. Traditional uses in folk medicines have been cited from Japan, China, Spain and the Scandinavian countries to support these claims.

The sharks named have included the Greenland shark (Somniosus microcephalus) and Gulper sharks (Centrophorus spp.) from Scandinavian waters, from around Papua New Guinea (their liver oil is exported to Japan for the manufacture of skin creams) and from the cold waters of the Western Pacific where they are known as Aizame sharks (a Japanese name (Liu, 1998) - one label described the Aizame sharks as scarce). The names of other sharks are shown in Table 1.

However, none of these claims have been conclusively tested. The writer was unable to determine the volume of such products in the market. Yet, as peoples around the world grow older and potentially have more health problems, it is likely that the demand for health products will increase.

Mention is made in the popular and technical literature of various components in the oils, especially oils from deepsea sharks. (The possibility of using cheaper methods for preserving livers of sharks, as suggested by Summers et al, namely, using ensiling instead of refrigeration, may be extended to sharks captured from warmer and shallower waters and could lead to reducing the fishing pressure on deepsea sharks for their liver oils.) The function of these compounds in contributing to health remains incompletely understood. Squalene, for example, is a biosynthetic precursor of cholesterol yet it is claimed that it helps to normalise the blood cholesterol levels in people who eat a lot of fatty foods.

Table 1 Sharks whose livers are harvested

Tope Shark (Galeorhinus galeus)

Piked Dogfish (Squalus acanthias)

Basking Shark (Cetorhinus maximus)

Stingray (Dasyatis pastinaca)

Cuban Dogfish (Squalus cubensis)

Catsharks (Galeus spp.)

Longfin Mako Shark (Isurus paucus)

Hammerhead Sharks (Sphyrna spp.)

Saw Shark (Pristiophorus nudipinnis)

Shortspine Spurdog (Squalus mitsukurii)

Leafscale Gulper Shark (Centrophorus squamosus)

Birdbeak Dogfish (Deania calcea)

Needle Dogfish (Centrophorus acus)

Lowfin Gulper Shark (Centrophorus lusitanicus)

Longnose Velvet Dogfish (Centroscymnus crepidater)

Mandarin Dogfish (Cirrhigaleus barbifer)

Kitefin Shark (Dalatias licha)

Roughskin Shark (Centroscymnus owstonii)

Bluntnose Sixgill Shark (Hexanchus griseus)

Thresher Sharks (Alopias spp.)

Great White Shark (Carcharodon carcharias)

Salmon Shark (Lamna ditropis)

Porbeagle (Lamna nasus)

Sawback Angelshark (Squatina aculeata)

Bramble Shark (Echinorhinus brucus)

Tawny Nurse Shark (Nebrius ferrugineus)

Sand Tiger Shark (Carcharhinidae taurus)

Shortfin Mako Shark (Isurus oxyrinchus)

Bignose Shark (Carcharhinus altimus)

Spinner Shark (Carcharhinus brevipinna)

Silky Shark (Carcharhinus falciformis)

Bull Shark (Carcharhinus leucas)

Blacktip Shark (Carcharhinus limbatus)

Oceanic Whitetip Shark (Carcharhinus longimanus)

Blacktip Reef Shark (Carcharhinus melanopterus)

Dusky Shark (Carcharhinus obscurus)

Sandbar Shark (Carcharhinus plumbeus)

Sicklefin Lemon Shark (Negaprion acutidens)

Wide Sawfish (Pristis pectinata)

Tiger Shark (Galeocerdo cuvier)

Whale Shark (Rhincodon typus)

Silvertip Shark (Carcharhinus albimarginatus)

Grey Reef Shark (Carcharhinus amblyrhynchos)

Giant Guitarfish (Rhynchobatus djiddensis)

Blue Shark (Prionace glauca)

Whitetip Reef Shark (Triaenodon obesus)

Smalltooth Sand Tiger (Odontaspis ferox)

Smooth Hounds (Mustelus spp.)

Greenland Shark (Somniosus microcephalus)

Snaggletooth Shark (Hemipristis elongata)


Plunket’s Dogfish (Centroscymnus plunketi)

One advertiser on the Internet claimed that squalene is helpful to people with heart disease, diabetes, hepatitis and allergies, among others. No mention of the specific varieties of these diseases was given. The same advertiser also said that it would generally enhance the quality of life, result in better skin and people who worked hard would feel less tired. Another substance found in shark liver oils in the early nineties, squalamine, was said to be a bactericide and later also believed to assist in curing infections involving yeasts, fungi and viruses and to strengthen the functions of the immune system.

Common fatty alcohols found in shark liver oil are chimylalcohol, batylalcohol, and selachylalcohol (also known as alkylglycerols or glycerol ether lipids, often shortened to G-E- lipids in popular publications and on the Internet). These have been cited as the compounds which support healthy immune system function when consumed in natural products such as shark liver oil. Since the fatty alcohols are more concentrated in lymph nodes, liver, spleen and bone marrow, and since these glands are in turn associated with the body's immune functions, the claims have also been extended to the immune functions of these organs. However, they have to be in their natural form to be most beneficial, a condition which is unlikely to attract funds for research. As a result, thorough testing has not yet been carried out.

Shark liver oil is packaged in capsules for oral consumption, and sold either in its purified form, or mixed with various other health enhancing substances for synergistic effects (also not yet rigorously proven). Labelling has become quite sophisticated, with quantitative details of ingredients, including amounts of squalene, omega-3 polyunsaturated fatty acids, alkylglycerols, vitamins, etc, and daily requirements may also be shown on the labels. Prices of capsules in Hong Kong were lower in September 1997 than the prices reported by Parry-Jones in 1996. He reported that bottles of between 40 and 180 capsules cost between HK$238 and HK$595 a bottle. However, in September 1997, the Australian, Canadian and American products were priced between HK$100 and HK$440 for a bottle of between 60 and 100 capsules, while a bottle of 80 capsules made in China cost HK$200.

Conservationists say that shark liver health products do not have any beneficial effects, and that they just result in the killing of more sharks. One estimated that a tonne of shark liver oil was produced from between 2,500 and 3,000 sharks (cited in Rose, 1996). Republic of Korea imported 364 tonnes of shark liver oil in 1994; about a million shark livers, probably from deep waters, were harvested for their oils.

3 SHARK CARTILAGE PRODUCTS

The cartilage of sharks contains chondromucoids, collagen, chondroalbumins (Suzuki, 1972) and other substances. One proximate analysis gave the following: 41% ash (with large amounts of calcium and phosphorus), 39% protein, 12% carbohydrate, 7% water, about 1% fibre and about 0.3% fat.

Shark cartilage, not just shark fin, has been used traditionally as food by the Chinese and Japanese. For example, Tanikawa (1985) described the processing of boiled-dried cartilage ("meikotsu") made from pieces of jaw, fin and head parts. These are soaked in hot water, the meat is removed and then the cartilage is boiled and sun-dried. The product was also exported to China and possibly eaten as a health supplement as well.

In Hong Kong dried shark cartilage is sold as vertebral columns or as a by-product of shark fin processing. The former are mostly imported into Hong Kong from north and south America. They are cooked and eaten as food or boiled in soups or with herbs to improve health.

The vertebral columns are sold as cylindrical rods as most of the vertebral processes have been trimmed off to simplify cleaning. The rods are of various diameters and about a metre in length. Most of the meat has also been removed and where it remains the rod is discoloured. Some rods are bleached white. In September 1997 these were retailed at HK$68 a kati (1 kati = 0.6 kg).

Fin cartilage is produced as a by-product of shark fin processing. The skin of the fin is peeled off, followed by the removal of the fin needles which are used in shark fin soup. The remaining fan-shaped fin cartilage is dried and sold. In September 1997 the price was HK$38 a kati. However, most of the fin cartilage is exported to Japan, believed to be the largest producer of shark cartilage products. Traders in Hong Kong understand that the blue shark cartilage is preferred in Japan because this contains the most gelatinous material.

Recent interest in shark cartilage is concentrated almost entirely on its use in health supplements and as an alternative cure for certain diseases. Manufacturers of shark cartilage products claim that individuals have been cured of dreaded diseases and that sufficient observations have already been recorded for health authorities to justify clinical trials. They have also suggested that, until more definite results are available, sufferers should be encouraged to try it under proper medical supervision. A Dr Lane has been credited as raising the profile of shark cartilage. Although he believes that certain forms of cancer can be cured by shark cartilage, he has adopted the view that it "is not a miracle elixir" and "should not be viewed as a substitute for conventional therapy" (Lane, 1996).

As with shark liver oil, it is also claimed that all chemical components in shark cartilage should be present in their natural proportions to enhance their synergistic effects. However, references are made to chondroitin as one of the active ingredients. Over 25 years ago, Suzuki (1972) described the extraction of chondroitin sulphate (also simply called chondroitin) by hydrolysing the chondromucoids in shark cartilage. She also reported then that it was believed to be a remedy for arthritis and a method of ageing retardation in Japan. As people live longer, arthritis and ageing retardation will attract more and more attention.

In fact, the use of shark cartilage products in health products and cosmetics overlaps that of shark liver oil, including its claims as a cure for various cancers. It is also used in the treatment of rheumatism, haemorrhoids, shingles, psoriasis and diabetic retinopathy. One advertiser additionally listed shark cartilage as effective against eczema, colitis, enteritis, poison ivy/oak, acne, varicose ulcers, phlebitis and cold sores.

The number of references to shark cartilage on the Internet far exceeded those to shark liver oils. On one day in February 1998, there were 123 184 references to cartilage, compared to 1 230 for shark liver oil on the same website. Yet, in the FAO publication in 1974 entitled Fishery Products edited by R Kreuzer, there was no mention of shark cartilage in contrast with the numerous references to shark liver oils. In Kreuzer & Ahmed (1978), there was equally scant reference to cartilage in comparison with shark liver oils although there was a reference to the use of chondroitin in eye drops, to which we will return.

Trade figures are not available for shark cartilage tablets or powder, nor for shark liver oil capsules. They are likely to remain poorly reported until the products are more clearly defined and regulatory procedures are in place.

A comprehensive report by TRAFFIC outlined the trade practices in the preparation and sale of shark cartilage. Rose (1996) observed that the processing of shark cartilage was labour intensive, as was the processing of shark fin, and was carried out in many parts of the world. Production was carried out when orders were received and there was a certain amount of specialisation; primary producers prepared the raw material, for example, but did not necessarily produce the tablets. Marketing of the tablets was also carried out by agents; for example, shark cartilage tablets sold in Singapore were purchased through agencies rather than directly from manufacturers. This was probably because of the small quantities sold in individual retail outlets.

Rose (loc cit) also concluded that shark cartilage production was probably not a threat to shark survival. An example she gave of financial returns to a United States-based harvester of a 23 kg shark was: cartilage US$2, fins US$25 and meat US$12.50. She mentioned that dried shark cartilage cost about US$1 per pound (0.45 kg) in the United States and Mexico, but Fahmeeda Hanfee (1996) reported that in India they fetched US$15-20 per kg, although it was unclear if it had been a more highly processed material.

Although there is much emphasis on quality control to preserve the shark cartilage in its natural form, there is very little reported on its preservation after the shark is landed in fishing boats.

Producers claim that to produce high quality cartilage products it is essential to remove meat and gristle by hand, without using strong or corrosive chemicals which may result in its denaturation. Natural food enzymes may be used for the final cleaning, after which the cartilage is sun dried (as with shark fin) and air dried if necessary. The cartilage chips are milled into a fine powder and then sterilized. During the above processes the cartilage is kept cool and the use of strong or corrosive chemicals and radiation are avoided. Cartilage tablets or powder may be sold on their own or fortified with various health enhancers.

Prices of shark cartilage tablets have recently fallen in Hong Kong with the appearance of more brands and perhaps a healthy scepticism among consumers. Parry-Jones (1996) found that bottles of between 45 and 100 tablets cost between HK$310 and HK$868 a bottle, whereas in September 1997 a bottle of 30 tablets produced in Australia cost HK$60 and a bottle of 90 tablets produced in the USA cost HK$480. In Singapore in February 1998 a 30-tablet bottle cost S$15.

Labelling is sophisticated and shows the quantity of shark cartilage present. Other natural products believed to promote health may also be included to widen the functions of the product, and quantitative details and daily requirements may also be shown on the labels.

Unlike shark liver oil, which tends to glamorize deepsea sharks, shark cartilage is made from both deepsea and tropical sharks and the tablets manufactured from both types of sharks are sold in similar strengths. This may be one of the reasons why the species of sharks used for making cartilage tablets and powders have not been named (Rose, 1996). Unlike oils produced for internal use, which are taken only orally, shark cartilage is taken internally either orally or rectally, preferably rectally to avoid its digestion and the side-effects some people experience. The label on one package stated that "the most common side effects can include abdominal pain, constipation, diarrhoea, stomach upset, nausea and skin rash" and may also have "serious side effects, including stomach ulcers and intestinal bleeding". Better understanding of the product has also prompted warnings against taking the cartilage under certain conditions, including pregnancy, breast feeding, recent surgery and heart or circulatory problems. Lane (1996) supported oral use, citing studies which showed that little digestion of shark cartilage took place in the stomach before it was absorbed into the blood.

Chondroitin has been mentioned earlier. It has established its pharmaceutical use (Martindale, 1996). This standard text describes it as an acid mucopolysaccharide which is present in most mammalian cartilaginous tissues. It has been given to patients with ischaemic heart disease, for the treatment of osteoporosis and related disorders and hyperlipidaemia. A medium containing chondroitin sulphate A has been used to preserve corneas for transplantation and preparations containing it or its sodium salt have also been used as adjuncts to ocular surgery.

It is interesting to note that Indian traders referred to its connection with heart diseases when reporting their sales of shark cartilage to Europe (Fahmeeda Hanfee, 1996), a point hardly emphasised by traders and manufacturers of cartilage products in other countries.

Much attention is focused on the use of shark cartilage and shark liver oil for treatment of diseases. The layman is, however, much confused by conflicting information; terminally ill people looking for cures need guidance but may be unsettled by answers from their health professionals. It would be helpful if a committee could be formed to review the literature regularly to provide this guidance in a more organized fashion, possibly also lending impetus to better management and conservation of sharks.

The origin of some of these claims is probably to be found in studies where the growth of tumours in animals was slowed. This has been strengthened by observations that it limits the growth of cancer, especially cancerous tumours, by inhibiting the development of blood vessels in these tumours. Other diseases linked with this are arthritis, eczema, acne, ulcers, haemorrhoids and cold sores.

It has been claimed as "a major cancer breakthrough" by one advertiser on the Internet. But a study presented to a meeting of the American Society of Clinical Oncology in Denver in May, 1997 said that shark cartilage was inactive in patients with advanced stages of breast, colon, lung and prostate cancer (Shark News, 1997). An Internet release from the University of Florida (1998) stated that no convincing clinical trials were found to support the claim that it cured cancer. Nevertheless, we can expect a continued demand for shark cartilage because people desperate for a cure for terminal cancer will try any alternative treatment that offers a glimmer of hope.

4 SHARK SKIN PRODUCTS

Shark skin is eaten as food in some countries. In some islands in the South Pacific, it is considered excellent (Matthew, 1996). In Taiwan Province of China the caudal skin of the White-spotted Guitarfish, Rhynchobatus djiddensis (Chen et al, 1996) is valued above all other shark skin. In countries where it is eaten, the skin is usually dried or smoked before it is finally cooked, and may have some meat attached as well. However, only a small amount of skin is eaten around the world.

The Chondrichthyes have rough and hard placoid scales (Marshall, 1962), which are usually minute, but vary greatly in shape; they can also develop in certain parts of the body into prominent tubercles or spines. When set closely together, these small scales give the skin surface the character of fine emery paper or cloth, which has resulted in its being used for sanding wooden and ceramic objects. Untanned skins are called shagreen, a term which includes the untanned leather from horses and seals (Tanikawa, 1985). Shagreen was formerly used for various polishing purposes in the arts, for armour, sword-hilts, and as a striking surface for lucifer matches.

Since each placoid scale body has the same basic structure as a tooth and differs in superficial structure and arrangement in different groups, they are used for identification (Marshall, 1962). The stingray carries a sting, which is a highly specialized and dangerous integumentary structure that is characteristic of the dasyatid sting rays (Family Dasyatidae).

Most of the skin which is used is made into leather. Kreuzer & Ahmed (1978) describe the cutting and skinning of sharks, and the grading of skins, which are usually salted before storage and transportation to the tannery.

Shark skin is tanned in much the same way as the skins of land animals. Tanikawa (1985) describes the process in detail and distinguishes between that in Japan, where hydrochloric acid was used, and the United States' use of sulphuric acid. He also describes the processes used in the tanning of fish skin.

In Japan the hides of whale and shark were used to produce leather until the 1940s (Tanikawa, loc cit). This industry was threatened when considerable quantities of land animal hides were imported and never regained prominence. An entry in the Encyclopaedia Britannica (1972) states that by the early 1960s about 97% of the world's supply of hides and skins derived from the production of meat or wool was tanned into leather. It is no surprise then that shark and fish skins moved into niche-leather markets in Japan, providing textural and beautifully speckled colours for purses, hand-bags, Japanese sandals, watch straps, etc. This is probably an extension of the niche established by the elegant and expensive Boroso leather, which is made from the hides of small Morocco sharks; the denticles are not removed but instead polished to a high gloss.

Although a market for shark leather developed in the USA, Rose (1996) found that it was difficult to sustain. Among the various reasons she cited, its use in protecting the attached meat against physical, chemical/biochemical and bacteriological deterioration may have been the most important. Moreover, shark is not necessarily the poor man's meat now that its handling is much better understood. The production of good quality meat requires that the shark landed on board fishing boats be gutted, washed in fresh water, stored in ice or refrigerated, which results in the loss of hides of good quality. The usual shark fishery also found it difficult to supply the necessary numbers of hides consistently to sustain an industry. It is in those countries where dried/salted meat of the larger sharks (preferably a meter and a half in length or larger) is produced that the shark skin industry has been able to survive. One such country is Mexico where there are a number of tanneries. It is also next door to the United States where a relatively ready market for shark skin products exists.

Products made from shark skin, either with or without denticles, as advertised on the Internet include shoes, cowboy boots and sandals, wallets/purses, coin/key fobs, belts, key cases, lighter cases, cigar cases, watch bands, gun holsters and knife holders. Some advertisers on the Internet also offer to make items according to their customers' designs, including choice of colours, and presumably leather specifications; the terms and conditions have to be negotiated of course. In India, besides the above items, shark skin is also made into grips for scooter/bicycle handle covers.

Rose (1996) provides a comprehensive summary of TRAFFIC's survey of the world's markets and trade in shark leather. The demand for shark leather is not believed to threaten the existence of sharks. A list of the species of sharks used for leather is listed in Table 2.

Table 2 Sharks whose hides are used as leather

Tiger Shark (Galeocerdo cuvier)

Nurse Shark (Ginglymostoma cirratum)

Lemon Shark (Negaprion brevirostris)

Dusky Shark (Carcharhinus obscurus)

Sandbar Shark (Carcharhinus plumbeus)

Bull Shark (Carcharhinus leucas)

Porbeagle (Lamna nasus)

Shortfin Mako Shark (Isurus oxyrinchus)

Scalloped Hammerhead (Sphyrna lewini)

Shortnosed Saw Shark (Pristiophorus nudipinnis)

Blue Shark (Prionace glauca)

Taiwan Gulper Shark (Centrophorus niaukang)

Great Hammerhead Shark (Sphyrna mokarran)

Spotted Wobbegong (Orectolobus maculatus)

Ornate Wobbegong (Orectolobus ornatus)

Tasselled Wobbegong (Eucrossorhinus dasypogon)

Spinner Shark (Carcharhinus brevipinna)

Great White Shark (Carcharodon carcharias)

Broadnose Sevengill Shark (Notorynchus cepedianus)

Thresher Sharks (Alopias spp.)

Tawny Nurse Shark (Nebrius ferrugineus)

Basking Shark (Cetorhinus maximus)

Piked Dogfish (Squalus acanthias)

Kitefin Shark (Dalatias licha)

Sawback Angelshark (Squatina aculeata)


5 SHARK TEETH AND JAW PRODUCTS

Sharks have powerful jaws. Some sharks have sharp and pointed teeth with rough cutting edges adapted for predation on other fishes. Others have flattened teeth adapted for crushing the shells of the crabs and molluscs on which they feed. According to Kreuzer & Ahmed (1978) small shark teeth are little used by humans. The larger ones have been used in traditional weapons and incorporated into ceremonial items or they are made into trinkets, curios or jewellery, especially as souvenirs for tourists.

The uses of teeth and jaws of sharks have been surveyed by TRAFFIC and summarised in Rose (1996). These include their use in traditional art works in certain islands in the South Pacific. The Gilbertese lash the teeth of sharks to the cutting edges and the spike of stingrays to the points of their traditional fighting swords. Shark teeth are used for cutting in Hawaii, and have also been fitted as knives, war clubs and other weapons.

The other more recent use of shark teeth is more selective. Compared to meat, liver and other easily denatured products, teeth are certainly easier to harvest and preserve. Rose (1996) cited earlier sources indicating the Mako, Great White and Tiger sharks as the species preferred for their teeth, because of their large size. Advertisements have appeared on the Internet offering teeth from precisely these sharks for sale. The teeth may be set in precious metals or encased in other materials, e.g. leather of various colours, and worn as necklaces. A company in Australia also enhance their setting with opals. The largest tooth (at 2 inches) the company offered from the Mako shark, set in either silver or gold, was priced at US$129.95. The smallest mako tooth advertised was 1 inch, set in the same way and offered at a price of US$39.95.

The jaws of sharks are also stuffed and offered for sale on the Internet. The jaws of certain sharks have been eaten as traditional food.

The display of teeth and jaws for sale is usually confined to tourist areas in Asia, America, Europe and Africa. The volume of teeth and jaws is not clearly known, but obviously they are by-products of shark fishing. Since they do not need preservation they may even be collected by traders only when their inventory is low.

6 OTHER USES

The following is a compilation of items which have been observed by various writers from around the world and recorded in some detail by Rose (1996).

7 REFERENCES

Chen, G C T, K M Liu, S J Joung and M J Phipps. 1996. Shark fisheries and trade in Taiwan. TRAFFIC East Asia. 48 pages.

Encyclopaedia Britannica. (1972)

Fahmeeda Hanfee. 1996. The trade in sharks and shark products in India: a preliminary survey. TRAFFIC International. 28 pages.

INTERNET Websites. January - March, 1998.

Kreuzer, R (Ed.) 1974. Fishery products. FAO and Fishing News (Books) Ltd. 462 pages.

Kreuzer, R and R Ahmed. 1978. Shark utilization and marketing. FAO, Rome. 180 pages.

Lane, I W and L Comac. 1996. Sharks still don't get cancer. Avery Publishing Group. 246 pages.

Liu, K W. 1998. National Taiwan Ocean University. (Personal communication)

Marshall, A J. 1962. 7th Edition of Parker & Haswell: A text-book of zoology. Macmillan & Co. Ltd.

Martindale - The Extra Pharmacopoeia. 1996. 31st Edition. The Royal Pharmaceutical Society of Great Britain.

Matthew, P. (1996) The Oceania region's harvest, trade and management of sharks and other cartilaginous fish: Solomon Islands, Western Province Overview. TRAFFIC International.

Miwa, K. 1972. Fish oil and fish liver oils. In: Utilization of marine products. Overseas Technical Co-operation Agency (OTCA), Government of Japan. 7 pages.

Parry-Jones, R. 1996. TRAFFIC report on shark fisheries and trade in Hong Kong. 57 pages.

Rose, D A. 1996. An overview of world trade in shark and other cartilaginous fishes. TRAFFIC International. 106 pages.

Shark News. June 1997. Newsletter of the IUCN Shark Specialist Group.

Summers, G and R Wong. 1992. Cosmetic products from semi-refined shark liver oil. INFOFISH International, 2/92. pp. 55-58.

Summers, G, R Wong and L Eyres. Undated. Handling and processing shark livers for the recovery of squalene and diacyl glyceryl ethers. DSIR Crop Research Seafood Report No. 1, New Zealand. 34 pages.

Suzuki, T. 1972. Pharmaceutical marine products. In: Utilization of marine products. OTCA. 3 pages.

Tanikawa, E. 1985. Marine products in Japan. Koseisha Koseikaku Co. Ltd., Tokyo. 506 pages.


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