The document discusses the Indian mackerel species Rastrelliger kanagurta. It is found along coastal regions in the Indian Ocean and western Pacific Ocean. R. kanagurta contributes over 95% of total mackerel catch in Indian waters. It is a pelagic fish that travels in large shoals and feeds on plankton. The mackerel fishery is an important industry for India, though conservation efforts are needed to prevent overfishing of juveniles.

1. By
Saswata Maitra

2.  The Indian Mackerel belongs to
Family- Scombridae
Genus- Rastrelliger
 A total of 3 species are found in Indian
waters-
I. R. kanagurta
II. R. brachysoma
III. R. faughni
 More than 95% of the total mackerel catch is
contributed by Rastrelliger kanagurta.
 Nearly 90% of world catch of Indian Mackerel
is contributed by India alone.

3. Distinguishing features of R.kanagurta
 Head length equal to the height of the body.
 First dorsal spinous, first spine shorter than
second.
 Second dorsal soft rayed.
 Caudal deeply forked with pointed lobes.
 Few golden yellow bands present along and
below lateral line.
 Dorsal and anal finlets 5 or 6 in number.

4. So how would u differentiate R.kanagurta,
from R.brachysoma & R.faughni
 R.brachysoma can be easily differentiated
from R.kanagurta by its short head which is
much shorter than greatest depth of body
and is marked by the absence of longitudinal
yellow bands and by the presence of black
spots.
 R.faughni has even shorter head, with shorter
mandible & maxilla with shorter and fewer gill
rakers. Absence of both longitudinal bands
and black spot differentiates it from other
other two.

6.  Rastrelliger kanagurta is extensively found in
tropical indo-pacific regions between 30°N
and 30°S latitudes and 30°E and 160°W
longitudes.
 Countries it occurs are- coastal waters of
Eastern Africa north of Durban, Seychelles,
Madagascar, Mauritius, countries bordering
red sea and Persian gulf, Pakistan, India
including Andaman & Nicobar islands, Sri
Lanka, Myanmar, Malaysia, Thailand,
Indonesia, Cambodia, Northern Australia,
Polynesia, Micronesia, New guinea, China,
Taiwan, Philippines and Hawaiian islands.

7.  R.brachysoma is also found in Indian waters
however its presence is restricted to the
southern African waters, Andaman sea, Malaysia,
Thailand, Indonesia, Philippines and solomon
islands.
 Occurrence of R.faughni has been recorded from
Taiwan, Philippines, Indonesia and east coast of
India.
 R.brachysoma
 R.faughni

9. FOOD AND FEEDING HABITS

10.  Surface feeders of inshore waters
 Ingestion is mainly through straining by well
developed feathery gill rakers.
 Food items- phytoplankton and zooplankton.
 Phytoplankton- comprises mainly diatoms,
Coscinodiscus, Pleurosigma, Chaeotoceras,
Eragillaria, Thalassionema, Nitzschia,
Rhizosolenia, Skeletonema and Biddulphia and
dinophyceae, Ceratium, Peridinium, and
Dinophysis.

11.  Zooplanktons mainly comprises of :-
 Copepod crustaceans represented by- Oithona,
Acrocaianus, Eucalanus, Temora, Euterpina and
Acartia.
 Other food organisms include Cladocerans,
Cirripede larvae, mysids, sergestids (Acetes),
amphipods, decapod larval stages of nauplius,
protozoea, zoea, and mysis stages of prawn,
alima larvae, polychaete worms, foraminiferans
and molluscan larvae.

13. REGION SIZE AT AGE
FIRST
MATURITY
R.kanagurta of 19-22.4cm 2 years
west coast of
India
R.Kanagurta of 25-25.9cm 3 years
Andaman sea

15.  R.kanagurta is heterosexual
 However sexual dimorphism is not
distinguishable from external characters.
 Sexes can be separated from gonadal
examination only after attaining size of
12cm.
 As stated before the general age of attaining
maturity is about 2years.
 There is strange regional difference in the
spawning patterns, explained in next
segment.

17.  The Indian Mackerel has been found to have 2
spawning season depending upon monsoon
season:-
 Intensive spawning and Supplementary
spawning seasons.
 The spawning seasons not only varies along
south-west and south-east coast but also along
the south-west coast from South Canara and
Mangalore coast in karnataka to Vizhingam in
Kerala.
 Eggs are pelagic in nature and contains a single
oil globule.

18. AREA SPAWNING
SEASON
West coast (in general) Corresponds with
southwest monsoon
July-August(intensive
spawning)
Nov-Dec(supplementary
spawning)
East coast (in general) Corresponds with
northeast monsoon
Oct-Dec(intensive
spawning)
April (supplementary
spawning)
Andaman sea October-April (1st
spawning)
No other data available

20.  No of batches and amount of eggs liberated
by Mackerels in 1 spawning season remained
unknown for a long time.
 It was later established that a 28cm
R.kanagurta releases its eggs in 3 batches in
1 spawning season.
 Eggs released in each batch and total
fecundity is given in the following table:-
Batch no. Eggs Total
released fecundity
1 45,000
2 27,000 1,10,000
3 38,000

22. After extensive research work from CMFRI from
year 2002-2005, the sex ratio in R.kanagurta
was found to be 1:1. i.e 1 female per every
single male.

24.  Mackerels are shoaling fish.
 They do not move in small schools or in few
numbers but in millions or even billions!
 Shoals are differentiated into fish of same
size groups comprising a single shoal
moving together steadily in the same
direction.
 Shape of the shoals- crescentic or arrow
head formation
 Shoal size- 100metres – a few kilometres
 Moving speed- 8-10miles/hr
 During day they can be spotted as a long
dark patch moving in water
 During night they emit luminiscence which
helps them in moving , but also helps in
scouting for the fishermen

26.  Fishing is mainly carried out in neritic waters
along the west coast up to a depth of
25metres.
 Fishery is mostly supported by juveniles of
size range 16-18cm.
 Main landing centre's are- Ratnagiri, Malvan,
Goa, Karwar, Malpe, Tellicherry, Calicut,
Cochin and Alleppey on west coast,
Mandappam, Nagapattinam, Kakinada, Vizag
& some parts of Orissa and West Bengal on
east coast (accidental catch).
 West coast contribute a mammoth 73% of
total Mackerel catch, while east coast
contributes 27%.

28. Basic Crafts used for fishing on west coast
are:-
 Dug-out canoes
 Canoe boats
 Plank-built boats, &
 Catamarans
Types of gears used are:-
 Boat seines
 Beach seines or drag nets
 Gill nets- comprising mainly drift nets, &
 Cast net

31. REGION CRAFTS USED GEARS USED
MAHARASHTRA DUG OUT CANOES- Pagar Beach Seine-Rampani payawada
and Thoni Drift Gill net- Bongdajal
CANOE BOATS-Akada hodi Cast net- Pag
KARNATAKA DUG OUT CANOE- Thoni Drift Gill net- Kandadi bale, Patta
CANOE BOAT- Pandi Beach seine- Rampani, Kairampani
KERALA DUG OUT CANOE- Odam Drift Gill net- Ozhuku vala, Ayila-
and Thoni chala vala
CANOE BOATS- Vallam Beach Seines- Karamadi&kara vala
CATAMARAN- Kattumaran Boat Seines-Ayilla koli vala, Thangu
vala, Odam vala, Madi vala, Paithu
vala.
TAMIL NADU PLANK BUILT BOAT- Boat Seines- Thuri Valai, Madi Valai
Vallam Beach Seines- Kara & Peria Valai
CATAMARAN- Kattumaran, Drift net- Vazhi & Vala Valai
Periamaran, Chinnamaran
ANDHRA PRADESH PLANK BUILT BOATS Beach seines- Pedda Vala
CATAMARANS- Padava Boat Seines- Iraga Vala
Gill nets and cast nets
ORISSA PLANK BUILT BOAT- Ber Beach Seine- Ber jal

33. YEAR OF LANDING CATCH (IN
‘000’TONNES)
1961-1970 52.04
1971-1980 85.60
1981-1990 95.35
1991-2000 190.47
2001-2005 113.59

34.  Year of maximum landing-2,91,080
tons(1989)
 Year of minimum landing- 20,780 tons(1968)
 Potential yield- 2,95,000 tons
 Current landings- 1,25,420 tons(2005)
 Region wise contribution of total catch:-
REGION PERCENTAGE
NORTH-EAST 3.5%
SOUTH-EAST 31.1%
SOUTH-WEST 55.2%
NORTH-WEST 10.2%

36. MIGRATION of Rastrelliger kanagurta:-
 The mackerel shoals enter the inshore waters of west
every year during post-monsoon period.
 The reasons for this migration is still a debatable
issue.
 Some of the possible reasons under considerations
are:-
i. For feeding purposes. However this may not be right,
as they do not migrate when the planktonic
population are at its peak in off south-west coast .
ii. Changes hydrological and meteorological
parameters. Mackerels seem to have higher
susceptibility to changes in temp. than salinity and
hence may migrate to cooler inshore waters.
 Migrations into the estuaries and backwaters upto as
much as 1.5 miles have also been noted in the
summer months.

37. RELATIONSHIP BETWEEN Mackerel and Oil
Sardine Fisheries of India:-
 The geographical distribution and the fishing season
of the 2 mainstay of Indian fisheries coincides with
each other.
 There exists an inverse relationship between the two
fisheries, i.e. lets say, a successful year of Mackerel
fishery coincides with the failure in catch of Oil sardine
fishery and vice versa.
 There are various factors that may lead to this-
I. Competition for food- this is the most obvious
assumption. However conclusive evidence has not
been found to supplement this theory.
II. Competition for space- it is assumed that the
spawning grounds for both fishes are in the same
regions, so there may exist a competition for space
for survival.

38. MANAGEMENT and CONSERVATION
practices in Mackerel Fishery
 The large scale exploitation of mackerel juveniles
along the southwest coast has lead to concerns about
the sustainability of the Mackerel stock in the country.
 42% of the catch comprises of juveniles of size groups
14-16cm.
 This has led to development of precautionary and
conservative strategies by limiting the fishing of
mackerels during monsoon months of July-September.
 Increasing the mesh size up to a minimum of 35mm is
another regulation that has been recently employed to
control overfishing of Mackerels.

39. THANK YOU