Fish processing

1. Utilisation of shark: Processing of shark meat,
removal of urea in meat, extraction of shark liver
oil, Vitamin A, squalene, ambergris, curing and
tanning of shark skin, shark cartilage.

2. • Sharks and their relatives provide a multitude of usable products including meat,
fins, liver, skin, cartilage and jaws and teeth.
• Unfortunately, tens of millions of sharks taken in fisheries each year have their
fins removed and their carcasses discarded overboard (Fowler and Musick,
2002).
• This practice, called finning, represents a considerable waste as the fins on
average make up only about 5% of the total weight of a shark (Vannuccini, 1999).
• This seminar briefly reviews the wide spectrum of uses that may be afforded by
sharks to encourage their more complete and effective use.
Introduction:

3. SHARK: AN OVERVIEW
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Superclass: Pisces
Class: Chondrichthyes
Under Class Chondrichthyes, sharks
have occupied two subclasses,
Subclass: Holocephali (chimaeras &
Silver sharks) and,
Subclass: Elasmobranchii (Sharks)

4. • Carcharhinus limbatus (Blacktip shark)
• Carcharhinus sorrah (Spottail shark)
• Carcharhinus dussumieri (Whitecheek Shark)
• Carcharhinus melanopterus (Blacktip reef shark)
• Carcharhinus macloti (hardnose shark)
• Galeocerdo cuvier (Tiger shark)
• Scoliodon laticaudus (spadenose shark)
• Rhizoprionodon acutus (Milk Shark)
• Sphyrna lewini (Scalloped hammerhead)
Species of sharks used for processing in India:

5. UTILISATION OF SHARK:
• Shark meat has been used as food in coastal regions for over 5000 years
(Vannuccini, 1999). Most historical use of shark meat was local because the meat
does not keep well without refrigeration.
• Interest in shark liver oil dates back hundreds of years. In the 18th and 19th
century, shark liver oil was used for lighting.
• Before and during the Second World War, shark livers were in demand for their
rich stores of Vitamin A. After that Vitamin A from shark liver oil has been largely
replaced by the synthetic product.
• In earlier skin and other internal organs were used as food also.
History:

6. MEAT:
• Sharks retain urea in their blood and tissues as part of their osmoregulatory physiology
(Musick and McMillan, 2002).
• This problem may be avoided easily by rapid bleeding of the freshly caught animal and
thorough washing of the carcass with seawater.
• Usually, the head, fins, gills and viscera are removed from larger sharks at sea, or in some
artisanal fisheries immediately upon landing.
• Subsequent soaking of the meat in a weak acid solution (citrus juice or vinegar) may remove
up to 90% of the urea (Gordievskaya, 1973).
• Spiny dogfish (Squalus acanthias) have the lowest and hammerheads (Sphyrnidae) have the
highest concentrations of several species measured (Gordievskaya, 1973).
• After bleeding and soaking, carcasses should be iced or frozen to prevent enzymatic and
bacterial breakdown.

7. Wash the fish in fresh
running water to
remove slime and dirt.
Place the fish on the
cutting board and cut
open the belly.
Cut across the throat in front of the
pectoral fin girdle and remove the
viscera from the belly
Cut open along the
mid-ventral line to
beyond the pelvic fins.
Turn the fish over
and cut off the dorsal
fins and tail.
Skinning: firmly fix the head on the ‘S’ hook
with the dorsal surface up, firmly grip the
belly flap and the base of the pectoral fins
and pull back towards the tail until the skin
comes off completely.
Remove the fish from the hook. Cut
from the dorsal surface behind the
gills and remove the head.
The end product thus obtained is shark meat
which is washed thoroughly and packed either
fresh or frozen according to the requirements of
the customer.
PROCEDURE OF PREPARATION OF SHARK MEAT FOR HUMAN
CONSUMPTION:

8. SKIN:
• Shark skin is consumed as food in several countries including the Maldives, Japan,
Taiwan and the Solomon Islands (Vannuccini, 1999).
• Skin from dusky, thresher and whale sharks as well as skin from the giant
guitarfish (Rhynchobatus djiddensis) is eaten in Taiwan.
• In Singapore and Malaysia, after processing, cooked shark skin is marketed as
“shark lips” or “fish lips.”
• Shark skin is processed into the gelatinous food “nikigori” in Japan (Kiyono, 1996).
• In the Solomon Islands shark skin is salted and then sun dried or smoked after
which it is boiled and the denticles are removed. The resulting product is then
made into soup with coconut milk (Matthew, 1996).

9. SHARK SKIN LEATHER:
• Untanned shark skin, with the rough denticles attached, is called shagreen and
has been used as sandpaper in woodworking and other industries for centuries.
• It has also been used to cover sword hilts (providing a slip-free grip) and as a
striking surface for matches (Kuang, 1999).
• Shark leather may be used to make a variety of products including furniture,
bookbinding, shoes and handbags.
• Historically, the major markets for shark leather products have been in the USA,
Germany, France and Japan with tanneries located in several countries.
• Today, because of environmental restrictions on the tanning industry and
problems with a steady supply of raw skin, most tanned leather is produced in
Mexico (Kuang, 1999).

10. SHARK HIDE FOR TANNING
INDUSTRY:
• A rare and expensive product known as Boroso leather
can be obtained by polishing the denticles of shark hide
to a high gloss.
• The hide can also be converted into a fancy leather by
removing the dermal denticles.
• Skins can generally be produced from sharks without
damaged body, which exceed 1.5m in length.
• The operation of skinning and salting must not take
more than 24 hours.
• Sharks meant for skinning should not be gutted, iced or
frozen beforehand. Fresh water will spoil the skin so
only seawater should be used for washing.
Skinning and Flaying
Soaking
Fleshing
Curing
Folding and Storage

11. Shark is generally skinned on a platform, usually on the deck of a fishing boat. It can also done by
suspending the fish from a hook through the upper jaw or with the carcass lying belly down on
the ground. A large and very sharp knife is used for the operation.
• Cut off all the fins except the tail.
• Insert the knife in the holes already made by the removal of the dorsal fins and cut forward to
the upper front of the head and back to the knob near the tail.
• Cut off the tail just in front of the knob.
• Cut around the head, behind the gills and pectoral fins, then ventrally and forward around the
edge of the lower jaw.
• Pull off the skin gently by freeing it from the carcass with the knife kept flat against the skin
from the head towards the tail.
• To avoid ‘sour spots’ i.e. areas of tissue breakdown, skinning must be done within 30 minutes.
1. Skinning or flaying:

12. • Wash the skin with seawater immediately after skinning to remove blood and slime.
Washing with a hose is preferable.
• Immerse the washed skin in a 6% brine solution for 3-4 hours to facilitate fleshing.
• Fleshing is the removal of the residual tissue from the fleshy side of the skin
after flaying. It is carried out with a ‘beaming knife’ and a stout ‘beaming
board’.
• After fleshing the tail end of the skin is split by cutting around the ventral fin
rudiments and vent and through the hole left by the anal fin.
2. Soaking
3. Fleshing

13. • Immediately after fleshing, the skin is washed with seawater and drained for 10
minutes.
• Mineral salt is applied generously (about one third of skin weight) on the fleshy side
and extra salt is rubbed along the cut edges. Salt must be neither powdered nor too
coarse in nature.
• Lay the salted skins flat, one on top of the other, flesh side up with ample salt
between each layer on a sloped platform so that the brine can drain away.
• The stacked skins must remain in this condition for a maximum period of 5 days.
• Complete protection from sun and direct sunlight must be maintained during this
time.
4. Curing

14. • At the end of the curing period the salted skins are removed one by one.
• The residual salt is shaken off from the cured skins and fresh salt is
applied on the flesh side of the skin.
• The skins are folded with the flesh side inwards to prevent loss of salt,
rolled into bundles and tied with twine.
• The bundled, cured skins are stored in a clean dry storage place after it has
been disinfected with insecticides and fungicides.
5. Folding & Storage:

15. SHARK LIVER:
• Shark liver has been eaten as food in China and the Solomon Islands and
elsewhere (Vannuccinni, 1999). The liver may be cooked fresh or salted
for later preparation.
• Shark liver is rich in various hydrocarbons and oils extracted from livers
have been used in the farming and textile industries, as lubricants, in
cosmetics, as lamp fuel, as a wood preservative on boat hulls and in the
pharmaceutical industry (Kuang, 1999).

16. SHARK LIVER OILS:
• Shark liver oil is used in the tanning and textile industries, as a lubricant and also as
a rich source of vitamin A.
• The livers weigh 10-25% of the shark’s body weight and contain 60-70% oil. Indian
sharks contain 2 to 180 kg of liver depending upon size, season etc.
• The easiest method of extracting shark liver oil is to mince the livers and boil them
with water in suitable containers. When the oil floats to the surface it is scraped off.
• A more efficient method of extracting shark liver oil is by digesting the chopped
livers with 1-2% by weight of sodium hydroxide or 2-5% of sodium carbonate at 82-
85°C. During the operation continuous stirring is required.
• This method results in the dissolution of all proteinaceous matter and complete
release of the oil. The oil is then separated using a centrifuge.

17. VITAMIN A:
• Shark liver is high in vitamin A and target fisheries for shark livers
developed in the 1940s.
• These fisheries were short-lived because of the development of synthetic
vitamin A (Kreuzer and Ahmed, 1978).
• Even so, the short but intense fishery for the soupfin shark (Galeorhinus
galeus) off the west coast of the United States led to rapid stock collapse
(Ripley, 1946) that has lasted for several decades (Camhi et al., 1998).
• Various forms of Vitamin A functions as a hormone and as the visual
pigment of the vertebrate eye.

18. SQUALENE:
• Squalene is a highly unsaturated aliphatic hydrocarbon found primarily in the non-
saponifiable fractions (85%) of the livers of deep-sea dogfishes (Squaliformes).
• This low density (0.86) compound provides buoyancy to the sharks (Thorson 1990).
• Squalene has been used as a fine lubricant because it is stable over a wide temperature
range (-75ºC to 330ºC) (Kuang, 1999).
• It is often hydrogenated to the more stable form Squalane before use (Anon, 1996; Kuang,
1999).
• The problem in developing further markets for squalene is that the squaloid sharks from
which it comes are among the slowest growing, latest maturing sharks known.
• Thus, these species may be quickly overfished if harvesting is not controlled at a low level
(Musick et al., 2000).

19. SQUALAMINE:
• Squalamine is one of several amino sterols (steroids) found in shark liver (Rao et al., 2000,
Moore et al., 1993).
• This steroid has been found to be a broad spectrum antibiotic which exhibits potent
bactericidal activity against both gram-negative and gram positive bacteria.
• Also, squalamine induces osmotic lysis of protozoa and is fungicidal (Moore et al., 1993).
• Squalamine has recently been shown to be an effective inhibitor of angiogenesis and
directly blocks blood vessel cell activation, migration and proliferation by many growth
factors (Sills et al., 1998).
• Genaera corporation (http://www.genaera.com/antiangiogenesis.htm) has recently
synthesized squalamine and although its pharmaceutical potential is vast, the future
demand for the compound directly from shark livers is probably minimal at best (as with
vitamin A).

20. AMBERGRIS:
• Ambergris is a fatty or pitch-like substance, grey or black in colour, produced in the
intestine of sperm whale, apparently when they are sick.
• Often, horny beaks of cuttlefish is found embedded in ambergris & therefore it is
believed that ambergris forms around the irritating indigestible beaks of cuttlefish on
which sperm whales mainly feed.
• When the mass of hard, grey ambergris become large, the accumulation may cause the
animal to die.
• Fresh ambergris has strong, unpleasant odour, but when exposed to air, it develops a
sweet, musty odour.
• It is widely used as an aphrodisiac product. Its main use in perfumery as a fixative as it
prevents the volatile oil from evaporating too quickly.

21. SHARK CARTILAGE
• Shark cartilage assumes importance because it contain condriothin sulphate
which is a mucopolysaccharide.
• It has therapeutic uses and is effecting in reducing inflammation, pain associated
with arthritis.
• Shark cartilage is used as food in China and Japan where it is boiled, cleaned of
meat and sun dried for later cooking.
USES AS FOOD:

22. DRIED CARTILAGE PILLS:
• Shark cartilage has been dried, powdered and delivered in pills or capsules.
• The market for shark cartilage pills expanded dramatically after the publication
of a book (Lane and Comack, 1992) that shows that sharks do not get cancer, an
assertion shown to be incorrect (Musick and McMillan, 2002) and that claimed
that shark cartilage pills could cure human cancers.
• The use of shark cartilage pills ingested orally has been found to be worthless in
the treatment of cancer in humans (Horsman, Alsner and Overgaard, 1998;
Leitner et al., 1998; Miller et al., 1998).
• However, cartilage in general is a good source of chonrdriotin and glucosamine
sulphate which is effective to reduce various forms of arthritis.

23. SHARK FINS:
• Shark fins are used to make a traditional shark fin soup in the Chinese culture and are among
the most valuable fish products in the world (Camhi et al., 1998).
• Only the fine collagenous fibers called “needles”, which support the fin margin, are used in the
soup.
• The lower lobe of the caudal is used because it contains the collagenous needles.
• Any meat left adhering to the base of the fin will spoil during drying thus the greater care is
taken in removing fins the greater their value (Vannuccini, 1999).
• Fins are traded during nearly all stages of processing. These include:
i. Wet fins; fresh, iced or frozen
ii. Dried “raw” fins; with skin (including denticles) and some radial elements intact. Fins are
sun-dried and turned frequently to facilitate drying to prevent curling. Drying may take 7-14
days to produce an acceptable product (18% moisture content (Vannucinni, 1999)). Dried fin
sets are usually packed in 25 kg sacks and dried “chips” in 50 kg sacks.

24. iii. Semi-processed or “cooked” fins; with the denticles and radials removed, but needle remain intact.
Fins are soaked in water for 8-10 hours (wet fins) or 16-24 hours (dry fins), then pre-heated to 80-90°C
until the scales and skin become loose. Then softened fins are placed into chilled water and the scales
and skin removed with a wire brush. After washing again, any remaining meat and the cartilaginous
radials are removed. The pre-processed fins are then dried on bamboo mats for 4-6 days.
iv. Fully processed fins, with the needle fans separated into individual strands. Semiprocessed fins may
be further processed to separate the needle bundles by soaking in water for up to 12 hours then boiling
for 5-10 minutes. The needles may then be easily separated from the surrounding membrane in cold
water.
v. Fin nets usually from smaller fins. The fin needles are boiled, separated, re-dried and packaged in
loose clumps.
vi. Ready to eat products; canned or instant shark fin soup.
• Most fins are traded as dried fins and imported for further processing in Hong Kong, Singapore or
Taiwan for domestic use or re-export.
Shark Fins:

25. SHARK FINS FOR SOUP:
Large, edible species of sharks are used to obtain suitable fins. In India the
fins of the following four species are usually collected for export:
• Hammerhead/round headed shark, Sphyrna zygaena
• Grey dog shark, Rhizoprionodon acutus
• Sharp-nosed/yellow dog shark, Scoliodon laticaudus
• Black-finned/black tip shark, Carcharhinus melanopterus

26. PROCEDURE FOR PREPARATION OF SHARK FINS
FOR SOUP:
• Wash the fish in running water to remove slime and dirt.
• Cut and remove the pectoral and pelvic fins on both sides.
• Cut and remove the dorsal fin and the tail.
• Remove the adhering flesh on the cut fins and washed them thoroughly in fresh
water.
• Add salt to the fins in the ratio 10:1. Give the cut-sides of the fins a liberal
sprinkling of salt and then apply a little lime. Leave the fins for 24 hours.
• Sun-dry the fins on clean mats until the desired level of 7-8% moisture is
obtained.
• The fins are then packed, stored and exported according the buyers’ specific
requirements.

27. PROCEDURE FOR PREPARATION OF SHARK FIN RAYS
FOR SOUP:
• Soak shark fins in clean fresh water, acidified to pH 2.5-5.0 with acetic acid for 48 hours.
• Scrape off the shagreen and continue soaking for 72 hours for fresh/raw fins and 120 hours for
dried fins. The soaking is done to soften the fins.
• For over-dried/long-stored dry fins, heat the softened fins together with 10% acetic acid for 60
minutes.
• Separate the rays manually from the loosened flesh if individual rays are required and wash
thoroughly in cold fresh water. In the case of tiny fins, the rays can be separated by gentle agitation
using a mechanical stirrer.
• Dry the fin rays thus separated in the sun on mats spread on clean raised cement platforms until a
moisture content of 5-8% is attained.
• Remove the dried fin rays from the sun and keep in shade for 30-60 minutes.
• Pack convenient quantities of dried fin rays in polyethylene bags.
• Store the dried shark fin rays in a dry, clean area.

28. CONCLUSION
• Though sharks have potent uses in industrial and consumptive basis, but only 5% of
these resources are used world widely. 95% of resources being wasted.
• Such waste is contrary to the United Nations Food and Agricultural Organization
(FAO) Code of Conduct for Responsible Fisheries (Article 7.2.2 (g)) which stresses the
importance of avoiding waste and discards in fisheries.
• In addition, the FAO International Plan of Action for the Conservation and
Management of Sharks (IPOA- Sharks) encourages full use of dead sharks and
retention of sharks from which fins have been removed.
• A strong word of caution is necessary here: full utilization of shark carcasses should
not be used as a pretext to fish unsustainably (Camhi, 2002).

29. REFERENCE
• “Management Techniques for Elasmobranch Fisheries”, FAO Fisheries
Technical Paper 474.
• “Shark Utilization, Marketing and Trade” by Stefania Vannuccini, FAO
Fisheries Technical Paper 389.
• “Post Harvest Technology of Fish and Fishery Products” by K. K.
Balachandran.
• www.fishbase.org
• www.wikipedia.org