Content uploaded by Baidya Nath Paul
Author content
All content in this area was uploaded by Baidya Nath Paul on Mar 23, 2016
Content may be subject to copyright.
Fishing Chimes
Vol. 30 No. 9/ December 2010
Water Soluble Vitamins in Aquaculture Nutrition
B.N.Paul, S.Das, S.S.Girj1 and S.N.Mohanty1
Regional Research Centre, Rahara
Central Institute of Freshwater Aquaculture
Kolkata -700118. Email:bnp63@rediffmail.com
'Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar-251 002
The name vitamin is derived from "vital
amines". This derivation was the result of
the consideration that all these substances
were amines. Vitamins are essential
organic substances for the normal
functioning, growth and maintenance of
body tissue and for the development of
multicellular organisms. These are
required in relatively small quantities for
the purposes mentioned above. A
compound is called a vitamin when it
cannot be synthesised in sufficient
quantities by an organism, and must
therefore be obtained from the diet. T-!lese
substances are distinct from the major
components of the food, i.e., protein,
carbohydrate and fat. These are an
absolute dietary requirement for animals.
Vitamins play a number of biochemical
functions. These include those such as
those of hormones, antioxidants and
mediators of cell signaling and regulators
of cell and tissue growth and differentiation.
Vitamins function as coenzymes, that help
as catalysts and substrates in metabolism
and also function as prosthetic groups.
Vitamins also act as coenzymes to carry
chemical groups between enzymes. For
example, foilic acid carries various forms
of carbon group - methyl, formyl
and methylene in the cell.
l1here are 13 essential vitamins and
each' one of these has a special role to play.
Vitamins are classified as water-soluble
and [tat-soluble ones. The fat-soluble
vitamins include vitamins A, D, E and K -
these are soluble in fat .Water-soluble
vitamins are not stored in the body, so they
need to be supplied through food every
day. Another aspect is that these are
destroyed by overcooking. These are
easily absorbed by the body. Nine water-
soluble vitamins are known as the B-
complex group: Thiamin (vitamin B,),
Riboflavin (vitamin 82), Niacin, Vitamin B6,
Folate, Vitamin 8
,2,
Biotin, Pantothenic acid
and Vitamin C. These vitamins are widely
distributed in foods. Water-soluble vitamins
like choline, inositol, and vitamin Care
required in larger quantities and have
functions other than co-enzymes.
,
information is available on the vitamin
requirement for common carp (NRC, 1993)
and
Peneaus monodon
(Reddy
et. a/.,
1999) .Specific deficiency diseases
are reported when these compounds are
not there in the diet. In mammals,
characteristic vitamin deficiency diseases
are observed, but in fish such symptoms
are less specifically identified. Both
qualitative and quantitative vitamin
requirements offish have been determined
by feeding chemically defined diets
deficient in a specific vitamin or vitamins.
Some compounds function as a vitamin
after undergoing chemical change to form
items such as f1 carotene and certain
sterols which are defined as vitamin
precursors. Many vitamins are destroyed
by oxidation; a process speeded up by the
action of light, heat and certain metals like
iron. To prevent such oxidation, some
commercial vitamin preparations are
dispersed in wax or gelatin, as they act as
a protective layer against oxidation.
Water Soluble Vitamins
Some of the water soluble vitamins are,
thiamin(vitamin 8,), riboflavin (vitamin B2),
pyridoxine (B
6),
pantothenic acid, niacin,
ascorbic acid, folic acid and choline. These
are described here under.
Thiamin:
Thiamine hydrochloride is a
water-soluble, colourless, crystalline
compound. It is stable to dry heat but it
rapidly breaks down in neutral or alkaline
solutions. The derivatives are thiamine
propyldisulphide, benzoylthiamine
disulphide, dibenzoylthiamine, and
benzoylthiamine monophosphate.
Thiamine hydrochloride and thiamine
mononitrate have been used as active
vitamins in test diets in fish nutrition
studies.
In metabolism of carbohydrate, thiamin
functions as the co-enzyme co-carbxylase
or thiamin pyrophosphate (TPP). As a part
of Pyruvate dehydrogenase, it acts to
convert pyruvate generated in glycolysis
into acetyl-CoA for entry into the
tricarboxylic acid (TCA) cycle. Thiamin
pyrophosphate is also used as a co-factor
for the enzyme a-ketoglutarate
dehydrogenase, which is a key point of
regulation in the TCA cycle.
Common sources for thiamin are peas,
beans, cereal bran and dried yeast. Fresh
glandular tissue is also a good source for
thiamin. Thiamin can be easily lost when
wet diet ingredients are held for too long
in storage or by preparing the diet under
slightly alkaline conditions or in the
presence of sulphite. Since thiamin is
relatively stable to dry heat, dry pellet
rations will retain the vitamin through the
pelleting process and subsequently during
dry-sealed storage. Wet or frozen diets
pose a problem because moisture content
allows increased chemical reaction and
causes the consequential increased
danger for biological hydrolysis and thus
leading to destruction of thiamin.
Obviously, wet or moist diet preparations
containing any fresh fish or shellfish tissue
must be used immediately or otherwise
suffer loss of thiamin through thiaminase
hydrolysis. The requirement of thiamin in
Mrigal is 20 mg/diet (Gupta and Dodia,
1997).
Deficiency signs are impaired
carbohydrate metabolism, nervous
disorders, loss ofwopetite. poor growth,
and increased sensitivity to shock. Skin
congestion and subcutaneous
haemorrhage occurs in carps fed on
thiamine - deficient diets. Poor appetite,
muscle atrophy, convulsions, instability and
loss of equilibrium, edema and poor growth
are the typical symptoms reported in carp,
catfish, salmon and trout. Nervous
paralysis occurs from thiamin deficiency.
Riboflavin:
Riboflavin is involved in
vital metabolic processes in the body and
it is necessary for normal cell function,
growth, and energy production. It is a heat
stable vitamin that is soluble in alkali but
insoluble in most organic solvents. It is a
yellow-brown crystalline pigment.
Riboflavin functions as a co-enzyme for
many oxidases and reductases such as
cytochrome c reductase, D-and L-amino
acid oxidase, xanthine and aldehyde
oxidase; succinic and fumaric
dehydrogenase. Riboflavin is involved with
r::s=
-------------------------------------------~ID---
Animals require vitamins as an
absolute dietary compulsion. Some
Fishing Chimes
Vol. 30 No.
91
December 2010
pyridoxine in the conversion of tryptophan
to nicotinic acid and this is the most
important aspect in the respiration of poorly
vascularised tissues such as the cornea
of the eye. As a whole, Vitamin 8
2
is
required in various cellular processes and
it is involved in energy metabolism i.e.,
metabolism of fat, ketone bodies,
carbohydrates and proteins. Riboflavin is
further needed to activate vitamin 8
6
(pyridoxine). It also helps in the creation
of niacin and assists the adrenal gland. It
may playa part in the process of red blood
cell formation, antibody production, cell
respiration, and growth.
So far as sources are concerned,
riboflavin is widely distributed in plants and
in animal glandular tissues. Specifically
stated, milk, liver, kidney, heart, yeast,
germinated grains, peanuts, soya beans
and eggs are rich sources of riboflavin.
Protection of finely ground raw materials
and mixing processes from iunlight or
intense artificial light is necessary to
minimise loss of the vitamin by conversion
to lumiflavin. As long as the ingredients and
the stored rations are protected from light,
most of the riboflavin activity will be carried
from the raw material into the feed. Deng
and Wilson (2003) reported the riboflavin
requirement of juvenile sunshine bass as
5mg/kg in dry diet.
Poor appetite and poor feed efficiency,
!followed by photophobia, bilateral
cataracts and general anaemia are
observed in fish when fed with riboflavin-
deficient diets. Striated constrictions are
observed on the abdominal wall. Skin
I
atrophy with abnormal pigmentation on
, both skin and iris is observed. Short body
, dwarfism has been reported in catfish.
histidine, cysteine and alanine. Fat
metabolism requires pyridoxine.
Pyridoxine plays a role in protein
metabolism as it is involved in the
synthesis of mRNA, and as a result,
carnivorous fish have stringent
requirements for pyridoxine in the diet. In
addition, pyridoxine can help in the
balancing of hormonal changes and aid
in immune system.
So far as sources of pyridoxine are
concerned, these are yeast, whole cereals,
egg yolk, liver and glandular tissues.
Pyridoxine compounds in phosphorylated
form present in agricultural products are
fairly stable but are labile to ultraviolet
radiation. Free forms of pyridoxal and
pyridoxamine are rapidly destroyed by air,
light and heat when in a moist form such
as in preparation of moist diets. The
requirement of pyridoxine in Singhi
(H.fossilis) is 3.21 mg/kg diet (Shaik
Mohamed, 2001) and in Penaeus
monodon it is 72-89mg/kg diet (Shiau and
Wo ,2003).
Pyridoxine is inter-related to protein
metabolism in fish. Pyridoxine component
in feed, containing 40-50 percent of protein,
when given to younger fish, is rapidly
exhausted, when it is pyridoxine-deficient.
Deficiency symptoms are: nervous
disorders, and alteration in control of
melanophore contraction. Gasping and
rapid breathing and flexing of opercles are
found in almost all the farming species.
Post mortem rigor mortis occurs very
rapidly. Carp, yellowtail, salmon and trout,
exhibit pre mortem rigor even a few hours
before death. Deficiency signs disappear
within a day or two after feeding with
pyridoxine hydrochloride.
biological roles, it is essential for all forms
of life. So it is obviously a key nutrient for
normal physiology and metabolism of a
growing fish.
Regarding sources of pantothenic acid,
these are cereal bran, yeast, liver, kidney,
heart, fish flesh, spleen and lung. The
calcium or sodium salt of pantothenic acid
is relatively stable and they can be
incorporated into either moist or dry fish
diets. Some loss of sodium or calcium salt
is incurred during autoclaving. Therefore
heat should be minimised during diet
preparation. Since the free acid is labile to
heat and also to acid alkali, some loss can
be expected during warm, moist diet
preparation or during warm or moist
storage. The requirement of pantothenic
acid in fish is 25-40 mg/kg of dry diet.
Regarding deficiency syndromes, the
symptoms of these are clubbed gills,
prostration, loss of appetite, necrosis and
scarring, cellular atrophy: gill exudate,
sluggishness and poor growth. The
opercules become distended and the
surface of the gills is often covered with
an exudate. Necrosis, scarring and cellular
atrophy-of the tender gill elements occur
and anaemia develops after prolonged
deficiency.
Niacin:
Niacin is one of the most stable
of the various 8 vitamins. Niacin is also
known as vitamin B, or nicotinic acid. It is
stable in the dry state and also in heat
conditions in mineral acids and
alkali.Other forms of vitamin 8, include the
corresponding amide i.e., niacinamide.
Niacinamide is a crystalline powder'
soluble in water and ethanol and the dry
material is stable up to about 60·C.
Niacin assists in the functioning of the
digestive system, skin, and nervous system
and it is also important for the conversion
of food into energy. The major function of
niacin in NAD and NADP is the removal of
hydrogen from substrates and the transfer
of hydrogen or electrons to another co-
enzyme in the hydrogen transport series.
Both NAD and NADP are involved in
synthesis of high-energy phosphate bonds,
which furnish energy for certain steps in
glycolysis, in pyruvate metabolism, and in
pentose synthesis. It is also involved in
lipid, amino acid and protein metabolism.
Pyridoxine:
Pyridoxine is also called
Ias Vitamin 8
6,
along with pyridoxal and
1
pyridoxamine. The stable form is
, pyridoxine hydrochloride and this is
i
soluble in water and is heat stable either
in acid or alkaline solution. It acts as a
co-enzyme in cellular metabolism and
, sensitive to UV light in neutral or alkaline
solutions. Vitamin supplementation comes
I
mostly from Pyridoxine and this assists in
I
the balancing of sodium and potassium.
It promotes the red blood cell production
in the form of pyridoxine hydrochloride. It
is the precursor of Pyridoxal phosphate.
Pyridoxine is required for the production
of the monoamine neurotransmitters
, serotonin, dopamine, norepinephrine and
epinephrine. It is involved and is essential
for tryptophan utilisation and metabolism
of glutamic acid, lysine, methionine,
~~~~~/---------------------------------------------------
..... --
Pantothenic Acid:
It is a white
crystalline powder readily soluble in water,
mildly acidic, and is almost insoluble in
organic solvents. It is stable to oxidising
and reducing agents, but is labile to dry
heat, hot alkali, or hot acid.
Pantothenic acid has a working role in
the synthesis of co-enzyme A (CoA) which
may act as an acyl group carrier to form a
acetyl co-enzyme A and other related
compounds.This has critical importance in
the metabolism and synthesis
of carbohydrate, protein and fats. The
acetyl co-enzyme A system is also
essential for the development of the central
nervous system. Pantothonic acid is
involved in adrenal function and for the
production of cholestrol. As pantothenic
acid participates in a wide array of key
So far as sources of niacin are
concerned, these are yeast, liver, kidney,
heart, legumes, and green vegetables.
Wheat contains a good amount of niacin.
Milk and egg products are also enriched
r:j
Fishing Chimes Vol. 30 No.
91
December 2010
with niacin. This vitamin is very stable since
it is generally found in co-enzyme form in
raw materials and it remains relatively
unaltered during diet manufacturing,
processing and storage. Singhi (H.fossilis),
as reported by Ibrahim and Shaik
Mohamed, requires 25mg/kg of niacin in
its diet.
Loss of appetite, lesions in colon, jerky
movement, weakness, edema of stomach
and colon, muscle spasm while resting and
poor growth are the common deficiency
syndromes on niacin deficiency.
Subcutaneous haemorrhages along with
congestion of skin were observed in
common carp in respect of niacin
deficiency.
Ascorbic acid: Ascorbic acid is
a sugar acid with antioxidant properties
and it is commonly known as Vitamin C. It
is a colourless, crystalline, water-soluble
compound having acidic and strong
reducing properties. It is heat-stable in acid
solution but is readily decomposed in the
presence of alkali. The destruction of the
vitamin C is accelerated by exposure to
light.
Vitamin C is an antioxidant vitamin
needed for the formation of collagen to hold
the cells together and for healthy teeth,
gums and blood vessels; it improves iron
absorption and resists infection. L-ascorbic
acid is a biological reducing agent for
hydroqen transport. It is involved in many
enzyme systems for hydroxylation, i.e.,
hydroxylation of tryptophan, tyrosine or
proline. It is involved in detoxification of
aromatic drugs and it also acts in the
production of adrenal steroids. It acts
SYfJ\'
ergistically with vitamin E and selenuim
to maintain activity of glutathione
pe\oxidase and superoxide dismutase. The
conversion of folic acid to folanic acid
re,guires vitamin C for the active coenzyme
from it. Vitamin C is responsible for
maintaining iron in its reduced state, thus
pr~serving activity of the hundreds of
enzymes that contain iron at the catalytic
sitk. The enzymes are iron-containing
prolyl- and Iysyl-hydroxylases that catalyse
th~ post-translational hydroxylation of
proline and lysine.
I
IL-ascorbic acid is unstable and most
of its acivities in practical diets are lost
during processing and storage due to
exposure to high temperature, oxygen and
light (Soliman et. al.,1987). It is reported
that 75% supplemented L-ascorbic acid
in ,shrimp feed could be lost during
processing (Shiau and Hsu,1993).
However, it can be reduced by coating or
encapsulating ascorbic acid in fat, ethyl
cellulose or other materials. Ascorbic acid
derivatives are more stable compared to
L-Ascorbic Acid.
Well known sources of vitamin Care
citrus fruits and green leafy vegetables.
Synthetic ascorbic acid is also available
commercially. The food must be protected
from aerobic oxidation and any moist feed
must be carefully protected from oxidising
agents, air and from metals like, copper,
iron which catalys e the oxidation of
ascorbic acid into biologically inactive form.
Fish food should be kept sealed or frozen,
and used rapidly to prevent loss of active
ascorbic acid.
The requirement of ascorbic acid as
reported by Mishra and Mukhopadhyay
(1996) in C. batrachus would be 69.0 mg/
kg diet. Mahajan and Agarwal (1980) found
that in Mrigal the ascorbic acid requirement
is 650-750 mg/kg. Mukhopadhay et a/.,
(1988) reported the ascorbic acid
requirement in Rohu is 1000mg/kg, as the
species lacked the enzyme L-gulanolactone
oxidase, the terminal enzyme for conversion
of glucose to ascorbic acid. A few authors
have detected the presence of L-
gulanolactone oxidase activity in the kidney
and liver of common carp (Yamamoto et et.,
1978; Soliman et al.,1985).
Symptoms of deficiency of ascorbic
acid are scoliosis, lordosis, impaired
collagen formation, altered cartilage, eye
lesions, haemorrhagic skin, liver, kidney,
intestine and muscle. The fish show
hyperplasia of jaw and snout. Hypertrophy
of the adrenal tissues and haemorrhage
at the bases of fins has been observed in
Coho Salmon.
Folic Acid: Folic acid contains p-
amino benzoic acid, glutamic acid and a
pteridine nucleus. The derivative of the
vitamin which functions as the co-enzyme
is tetrahydrofolic acid. Folic acid promotes
normal digestion and it is essential for
normal blood cell formation. It is involved
as a co-enzyme in one-carbon transfer
mechanism. Folic acid is involved in the
conversion of megaloblastic bone marrow
to normoblastic type. It has a role in blood
glucose regulation and improves cell
membrane function and hatchability of
eggs.
acid activity. Some requirement of Vit. C is
met by fishes consuming insects. The
activity of folic acid is lost during extended
storage and when material is exposed to
sunlight. Fish diets should be fed soon after
manufacture in order to prevent the loss
of folic acid activity. The folic acid
requirement in juvenile Tilapia is 0.82mg/
kg diet (Shiau and Huang, 2001)
Specific deficiency syndrome in fish is
macrocytic normochromic anaemia. Other
signs are poor growth, anorexia, anaemia,
lethargy, fragile fins, dark skin pigmentation
and infection of spleen.
Choline: Choline acts as a methyl
donor in trans-methylation reactions. It is
a component of lecithin which plays a vital
role in cellular structure and activity. It also
plays an important role in lipid metabolism
in the liver by preventing the accumulation
of fat in this organ. It serves donor methyl
groups in transmethylatin reactions and it
is a component of acetylcholine which is
responsible for the transmission of nerve
impulses.
Good sources of choline are wheat
germ, beans, brain, and heart tissue.
Choline hydrochloride is the commercially
available form. Optimal dietary choline
requirement for growth of Tilapia is about
1000 mg/kg diet (Shiau and LO,2000).
Deficiency symptoms include poor
growth and poor food conversion,
haemorrhagic kidneys and intestines,
impaired fat metabolism and increased
gastric emptying time.
Conclusion
The water soluble vitamins are dietarily
essential for normal growth and
physiological activity. Reddy et. a/. (1999)
reported that water soluble vitamins are
essential for Penaeus monodon. Ascorbic
acid is the most unstable one; so it should
be added in fish diet as it is water soluble,
but not L-ascorbic acid. There is also an
inter- relationship among ascorbic acid,
vitamin-E and selenium. They also play
an important role as antioxidants. To
enhance fish production in the farming
system one should add these vitamins in
fish feed. References
GUPTA, A.K. and PODIA, S. (1997).
Dietary Thiamin (Vit-B,) requirement of
Cirrhinius mriga/a fingerlings for growth
. and body composition. J.lnland
Fish. Soc. India, 29: 13-18
(iF'
~------------------------------------------~BI---
Yeast, green vegetables, liver, kidney,
glandular tissue, fish tissue, and fish
viscera are good sources of folic acid.
Insects contain xanthopterin which has folic
Fishing Chimes
Vol. 30 No.
9/ December 2010
MAHAJAN,C.L. and AGARWAL,N.K.
(1980) Nutritional requirement of ascorbic
acid by Indian major carp larvae, Cirrhinus
mrigala, during early growth.Aquaculture,
19:37-48.
MUKHOPADHYAY, P. K. (2001)
Nutrition and dietetics in carp culture
practices. Lecture delivered on sponsored
training programme on 'Applied Nutrition
in Freshwater Aquaculture" Education
Division of ICAR, New Delhi-110012, and
CIFA ,Kausalyaganga, Bhubaneswar.
MUKHOPADHYAY, P. K. and MISHRA,
S. (1996). Ascorbic acid requirement in
catfish fry Clarias batrachus. Indian J.
Fish., 43: 157-162.
NRC,(1993) Nutrient requirement of
fish. National Research Council.National
Academy Press, Washington DC,114pp.
REDDY, H.R.V, NAIK, M.G and
AN NAP PASWAMY, T.S. (1999). Evaluation
of dietary essentiality of vitamins for
Penaeus monodon. Aquaculture Nutrition,
5: 267-275.
SHAIK MOHAMED, J. and
IBRAHIM, A. (2001) Quantifying the
dietary niacin requirement of the
Indian catfish,
H.
to s
silis
(Bolch),
fingerlings Aquaculture research,
32 :
157-162.
SHIAU, S. Y. and LO, P.S. (2000)
Dietary choline requirement of
Juvenile hybrid tilapia. J. Nutr. 130 :
100-103.
SHIAU, S. Y. and HUANG, S. (2001)
Dietary folic and requirement for maximum
growth of Juvenile tilapia. Fisheries
Science. 67 : 555-659.
SHIAU, S.Y. and HSU T.S.,
(1993).Stability of ascorbic acid in shrimp
feed during analysis.Nippon Susian
Gakkaishi,59:1535-1537.
SHIAU,S.Y. and WU,M.H.(2003)
Dietary vitamin B6 requirement of grass
shrimp, Penaeus monodon. Aauecuna»,
225:
397-404.
SOLIMAN, A. K., JAUNCEY, K.,
ROBERTS, R. T., (1987). Stability of
ascorbic acid (vitamin C) and its forms in
fish feeds during processing, storage and
leaching. Aquaculture, 60: 73-83.
SOLlMAN,A.K., JAUNCEY,K. and
ROBERTS, R.J. (1985) Qualitative and
Quantitative identification of L- gulanolaclone
oxidase activity in some teleosts. Aquacu/t.
Fish. Manage., 16: 249-256.
WILSON, R.P. and DENG, D.F (2002).
Dietary riboflavin requirement of Juvenile
sunshine bass.Aquaculture, 218: 695-701.
YAMAMOTO,Y., SATO,M. and IKEDA,S.
(1978) Existence of L-gulanolactone oxidase
in some teleosta. Bull. Jpn. Soc. Sci. Fish.,
44 : 775-779.
i:li:lt:l
Turtle Conservation
programme organised
TREE Foundation, Chennai, and
Visakha Society for Protection and Care
of Animals (VSPCA) in association with the
Forest Department and the Fisheries
Department organised a sea turtle
conservation programme at
Bhumunipatnam and at the fishing harbour
Visakhapatnam on 9 Dec 2010. The
conservation programme was organised
as the Olive Ridley nesting season begins
by the end of December and goes on till
April. Sea turtle is protected under
Schedule I of the Indian Wildlife Act of 1972
, on par with lion, tiger and leopard.
I
According to Chairperson of Tree
: Foundation Dr. Supraja Dharini, some 50
I
fishermen from 10 villages participated in
I
the programme at the Fisheries
, Development Office at Bhimili adjacent to
Visakhapatnam and an equal number from
six villages at the Fishing Harbour,
Visakhapatnam. The joint awareness
programme is necessary to reinforce
community-based conservation with facts
and to equip them effectively to carry out
conservation measures along the coast.
Supraja Dharini, Pradeep Kumar
Nath and Raju of VSPCA, Abdus Saif,
Rescue and Rehabilitation Network
member of TREE Foundation spoke on
the conservation measures.
Saktheeswaran, who will stay at
Visakhapatnam to coordinate
conservation work, was present. The Sea
Turtle Protection Force members from
Chennai Pugalarasu and Ezhumalai and
Pavan Kumar form TREE Foundation's
Nellore Sea Turtle Conservation
programme interacted with the
community sharing their experiences.
A.P Fisheries Development Officers
Sumalatha of Bheemili and Sreenivas
Reddy of fishing harbour Visakhapatnam
were present.
Initiative: TREE Foundation pioneered
a successful community -based
conservation programme for endangered
Olive Ridley turtles nesting along the SOuth
eastern coast of India According to Dr.
Supraja, the objective of the awareness
programmes is to facilitate smooth
networking for turtle conservation along the
coast of Visakhapatnam, reducing
poaching of turtle eggs, prevention of
predation by stray dogs or jackals along the
coast with regular patrolling of the beach
by volunteers of Sea Turtle protection force
from the fishing community and spreading
awareness among fishermen to release
entangled turtles from their nets and not
chop off their flippers or kill them.
Two Blue Whales seen off
Mangalore coast
Two blue whales (Ba/aenoptera
musculus). the largest mammals on
: Earth, were recently spotted off the
~Mangalore coast during a marine survey
: carried out by the Central Marine
I Fisheries Research Institute (CMFRI)
i
Kochi. They were sighted - a rare
instance, say researchers - from the
ocean research vessel Sagar Sampada,
at a depth of 100 metres, from a distance
of more than 130 metres, said Anoop
Balan, researcher associated with
studying marine mamrnals in the
, Exclusive Economic Zone and contiguous
seas. Blue whales are not commonly
sighted in the Arabian Sea. There have
been no records of their presence there
since 2003. They are mostly found in the
deep waters off Sri Lanka, Dr. Balan said.
Live recording of blue whalers are rare
and the institute plans to step up
observations following the spotting, said
Dr. E. Vivekanandan, Principal Scientist
of the Demersal Fisheries Division of the
CMFRI in Chennai. Quoting a report, Dr.
Vivekanandan said a blue whale was
killed in a suspected propeller hit recently.
Blue whales are long-distance migrants
known to undertake long journeys in
search of food and mating grounds.
Recently, upwelling (an oceanographic
phenomenon that involves wind-driven
motion of dense, cooler, and usually
nutrient-rich-water towards the ocean
surface, replacing the warmer) was reported .
in the Malabar coast extending from
Kozhikode to Mangalore, making the stretch
abundant in fish and prawn varieties. The
whales could have come in search of food.
A few dolphins were also spotted during the
period. Dr. Anoop said. Dr. Vivekanandan
mentioned there was a possibility that blue
whales were already present in the Arabian
Sea. With new sightings, research activities
in this direction needed to be strengthened.
The blue whales belong to the Rorquals
family, which include the humpback, fin ond
minke whale. Their skin is grayish blue with
light grey mottling on the back. They can
grow up to 33 metres in length and weigh
up to 200 tonnes. "'''''''
~~~'
-----------------------------------
