India is among 17 megadiverse countries that hold 11.7% of world fish diversity. Of the total freshwater fish diversity of the country, 10-13% of total species have become endangered indicates widespread and massive degradation of aquatic fish habitats. The State of West Bengal is gifted with 7.5% of the water resource of the country and that is becoming increasingly scarce with the uncontrolled growth of population, expansion of irrigation network, and developmental needs. West Bengal has rich freshwater fish genetic resources constituting about 28.34% to the freshwater fish diversity of India

2. Introduction
• India is among 17 megadiverse countries which holds 11.7% of world
fish diversity.
• Of the total freshwater fish diversity of the country, 10-13% of total species have
become endangered indicates widespread and massive degradation of aquatic fish
habitats.
• The State of West Bengal is gifted with 7.5% of the water resource of the country and
that is becoming increasingly scarce with the uncontrolled growth of population,
expansion of irrigation network and developmental needs.
• West Bengal has rich freshwater fish genetic resources constituting about 28.34%

4. Current status of fish production (2017-2018)
Marine Fish
Production
Inland Fish
Production
Total (Lakh
ton)
West Bengal 1.85 15.57 17.42
India 36.88 89.02 125.9
5.016 %
WB stands 7th in
marine fish production
17.49 %
WB stands 2nd in
inland fish production
13.836 %
WB stands 2nd in total
fish production

5. Monthly per capita fish consumption (2011-
2012)
Rural Urban Rural (fish
consuming persons)
Urban (fish
consuming persons)
West
Bengal
Quantity(KG) 0.81 1.03 831/1000 792/1000
Value (INR) 77.63 130.46
India Quantity(KG) 0.27 0.25 265/1000 210/1000
Value(INR) 22.77 26.73
 World average of per capita fish availability- 20.50kg (in 2018)
 India average of per capita fish availability-9 kg
Source-DoFWB 2016

6. Water resources of west Bengal
Waterresource
Open water
resource (4.22
lakh ha)
River
Canals
Reservoirs
estuary
Enclose water
resource (3.94
lakh ha)
Tank& pond
Flood plain lake
Beels
Sewage fed fishery
Brackish water
• The state of West Bengal has 7.45% of
total water resources of our country
• Fresh water fisheries cover about 80
to 85% of total closed water system
in West Bengal.

7. Source-DoFWB 2016

8. Rivers of west Bengal
Rivers of west Bengal can be divided in to three division
1. Himalayan river
2. Chota Nagpur plateau rivers
3. Tidal rivers

9. Himalayan river
• Major Himalayan rivers are Ganga, Bhagirathi-hoogly, Mahananda, Balasan, Mechi,
Tista, Torsa, Jaldhaka
• Ganges enters West Bengal near Rajmahal and then flows in a south-eastern direction and divides into two
near north of Dhulian in Murshidabad. One branch enters Bangladesh as the Padma, while the other flows
through West Bengal as the Bhagirathi River and Hooghly River in a southern direction and reach to Bay of
Bengal
• The Teesta flow cutting deep gorges from north to south in the mountainous Darjeeling district; it enters the
plains at Sevoke and flows in a mighty stream on straight line towards the south east until it pours its waters
into the Brahamaputra in Bangladesh.
• Torsa, Jaldhaka, Kaljani, Raidak, Sankosh and Mahananda rivers are in the northern hilly region which rise in
the Himalayas and flow in a southernly direction through the districts of Darjeeling, Jalpaiguri, Cooch Behar
and North and South Dinajpur and enters Bangladesh.
• The Mahananda rises from the Dow Hills forest, near the town of Darjeeling and are fed by similar small
rivers like, Mahanadi, Balason, and Machi and runs in a zig-zag way through the district of Malda and joins
the Padma in Bangladesh.

10. Chota-nagpur plateau rivers
Major Chota Nagpur plateau rivers are Damodar, Mayurakshi, Ajoy,
Subarnarekha etc.
• Damodar originates from Chota Nagpur plateau in Bihar and flows through West Bengal and
joins hoogly river
• The Subarnarekha River after flowing for a short distance in West Bengal enters into Orissa.
• The Mayurakshi, Ajay, Damodar, Kangsabati, Rupnarayan and their tributaries which rise in
the Western plateau and high lands flow eastwards through the different districts of West
Bengal and joins the Bhagirathi on the right bank.
• The Dwarakeswar and Shilabati rivers join to form Rupnarayan.
• Kangsabati and Keleghai rivers join to form the Haldi. The Rupnarayan and Haldi fall into the
Hoogly river.

11. Tidal rivers
• These are the rivers of active delta region. Water of these rivers are
saline as these are influenced by tidal water.
• Major tidal rivers are Bartala, Saptamukhi, Jamir, Matla, Gosaba,
Haribhanga, Kalindi and Ichhamati.
• During low tides these rivers gets mostly dried, and in high tide they
overflows the banks.

12. Major Freshwater resource ( District wise )
• There is only one district namely Murshidabad which consists of more than 20,000 ha area under
river. Rest of the districts has less than 20,000 ha area under river.
• With respect to Beels, there are only two districts namely North 24-Pargana (8861.19 ha) and
South 24-Pargana (5749.47 ha) which have more than 5000 ha of Beels under their control.
• More than 3000 ha Beels are contained in 7 districts. Out of these seven districts, namely Malda
(4551.55 ha), Nadia (4271.61 ha) and Hooghly (3884.76 ha) have large area of Beels under their
administrative control for the development of the fisheries.

14. Marine and Brackishwater Area
• In the state of West Bengal, only three districts contain brackishwater
area. These are North 24 Pargana (35371.26 ha), South 24
Pargana (17759.00 ha) and Purba Midnapur (5227.00 ha).
• Total coast line of West Bengal is 158 km. The inshore and offshore
areas of Bay of Bengal in the Purba Midnapore districts are
respectively 777 Sq. km. and 1813 Sq. km.
• The Continental shelf area is 17049 Sq. km.

15. Source-DoFWB 2016

17. Review Of Available Studies On Biodiversity
• Different authors recorded different numbers of species in West Bengal.
• 65 species of fishes are recorded from the River Teesta [Acharjee et al 2012].
• 125 species [Mukherjee et al 2005] were mentioned from Darjeeling Himalayan upland.
• 46 species belonging to 7 orders, 18 families and 26 genera are recorded from
Damodar River, Burdwan district [Patra et al 2013].
• It has been also recorded 70 indigenous ornamental fish species belonging to
45 genera, 30 families and 9 orders [Basu et al 2012].
• A total of 155 fish species belonging to 49 families and 15 orders were recorded
from the tidal freshwater zone of the Hooghly estuary [Roshith et al 2012].
• A list of 172 species [Mahapatra et al 2014] were recorder from Sundarban.

19. River wise comparative Studies On fish-
diversity

20. Diversity of Special Significant Area
• There are two special significant area in West Bengal in respect to diversity and
international importance
1. Sundarban area
2. East-Kolkata Wetland
• Sundarbans is the largest protruding delta on this
planet, which is shared between Bangladesh (~60%)
and India (~40%).
• The Indian Sundarbans (Latitude 21° 32’-22°40’N,
Longitude 88° 22’-89°0’E) in the north east coast of
India occupy 9630 square kilometer and are bounded
by River Hooghly in the West, River Raimangal in the
East, Bay of Bengal in the South .
• The East Kolkata Wetlands (EKW) (22°27’ N and
88°27’ E), are a complex of natural and human-
made wetlands lying east of the city of Kolkata.
• The wetlands cover 125 km2, and include salt
marshes, sewage farms and settling ponds.
• In August 2002, 12,500 hectares of the EKW area
was included in the ‘Ramsar List’ making it a
‘wetland of International Importance’.

21. Diversity of Sundarbans
(A Special Significant Area)
• About 15-20% of the total fish requirement of Kolkata market is being
supplied from Sundarbans. A total of 172 species of fishes, 20 species
of prawn and 44 species of crabs including two edible crabs have
reported . [Gopal et al. (2006)]
• The group of islands is interspersed by innumerable rivers, creeks, etc.
which makes most of the area inaccessible and rest is reserved forest,
falling under the Sundarbans Biosphere – a world heritage site.
 1984- National park
 1987- UNESCO world heritage site
 2019-Ramsar site

22. • These wetlands are used to treat Kolkata’s sewage, and the nutrients
contained in the waste water sustain fish farms and agriculture. It comprises
254 sewage fed fisheries, small agricultural plots and solid waste farms.
• The commercially important aquatic species in the EKW includes 50 species of
fish, 11 species of prawns, 3 species of crabs and 20 species of molluscs.
Among the 50 species 17 are cultured and 33 are wild species [Mahapatra et
al.(2012)]. 13,000 tonnes of fish are produced annually in ponds managed for
wastewater aquaculture.
• Development of vegetation based microenterprise (150 units), ornamental fish
culture (300 units) and fish cum duck rearing (300 units) for livelihood
diversification of EKW communities.
Diversity of East-Kolkata Wetland
(A Special Significant Area)
 2002- wetland of
international importance
(Ramsar site)

23. Endemic species
• Noemacheilus devdevi (Hora, 1935). Mainly
found at all stream below Darjeeling. The fish
is IUCN listed nearly threatened species.
• Noemacheilus multifasciatus (Day, 1878).
Mainly found at Darjeeling.
• Balitora brucei (Gray, 1830). Commonly known
as Gray’s Stone Loach. The fish is IUCN listed
nearly threatened species.

24. New Species
• During the last decade many fish species
from the biodiversity hotspot area like North
East and Western Ghat region have emerged
new species.
• Britz discovered a new species Channa
andrao from Jalpaiguri, West Bengal [Britz R
It is described in 2013 by Ralf Britz.
Channa andrao

25. State fish
• Tenualosa ilisha is the state fish of west Bengal.
• It shows anadromous migration. It can grow up to 60 cm in length with
weights of up to 3 kg. The fish schools in coastal waters and ascends up
the rivers for around 50-100 km to spawn during June to September and
also in January to March.
• Production trends indicate that the Hilsa production declining year to
year due to the over exploitation of juveniles and brooders are the main
threats of Ilisha.
• If any population is affected by the ‘recruitment overfishing’, the
population might be seriously hampered to attain the sustainable yield in
the long run, so the fishing regulation must be strong for Hilsa to make
this species sustain for a long time in future.

26. 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11 2011-12 2012-13 2013-14 2014-15 2015-2016
Marine 19061 16072 9430.64 11744 10560 54265 20949 7699 9407 8908 13405
Inland 8520 7156 5207 4256 3445 5530 3172 980 1029 984 1127
Total 27581 23228 14637.64 16000 14005 59795 24121 8679 10436 9892 14532
0
10000
20000
30000
40000
50000
60000
70000
UNIT-TON Hilsa catch of West Bengal
Marine Inland Total Source-DoFWB 2016

27. Threatened Species
• Conservation status of the freshwater fishes of the West Bengal suggests
that 10 species are under endangered category, 11 species are under
vulnerable category, 27 species are under near threatened category, 22
species are data deficient and 29 species have not been evaluated against
IUCN red list criteria.
• Out of the freshwater fishes, 17.97% are under threatened or near
threatened categories and 82.02% are under non threatened categories.
• Species under endangered category include Gudusia chapra, Botia
almorhae, Botia lohachata, Tor putitora, Tor tor, Pangasianodon
Source-Mogalekar et al. (2017)

29. Source-DoFWB West Bengal fisheries policy-2015

30. Fisheries Potentials of West Bengal
• The age-old traditional farming methods of shrimp and finfish
with some modification still exist because of their simplicity
and cheapness in West Bengal. Brackish water farmers of West
Bengal started adopting white leg shrimp farming late compared to
other Indian maritime states.
• The state of West Bengal has the maximum brackish water area,
which is estimated to be nearly 4.05 lakh ha, but only 14.56%
potential area is under culture (MBSA action plan-2022).
• These data suggest that though West Bengal has the maximum
brackish water area, the culture and production of brackish water
species and export is still in the early stages.

31. Threats to Fish Diversity
• Habitat alteration
• Destructive fishing
• Exotic fish species
• Overexploitation
• Climate change

32. Habitat alteration
• A habitat is a place where an organism makes its home. A habitat meets all the
environmental conditions an organism needs to survive.
• To support and fulfil human needs humans are continuously encroaching and
altering nature and natural resources, which is destroying the natural habitats.
• Damming, deforestation, diversion and withdrawal of water for irrigation, urban
and industrial consumption has caused large scale changes in the channel bed
and hydrology of the river in terms of flow, flow-rate, flood-rhythm and regime.
• Dam impedes upstream spawning migration of fishes and displaces populations
from their normal spawning grounds. It may also result in separating a population
into two smaller groups as in Hilsa (Tenualosa ilisha) above and below the Farakka
barrage. The migration routes of important native fishes like mahseer (Tor
putitora and T. tor) and snow trouts (Schizothorax richardsonii and S.
plagiostomus) have been blocked.

33. Destructive fishing
• Destructive fishing by the use of dynamites, electric shocks and
poisoning and brood fishes in spawning season and juveniles during
post-monsoon periods have affected a number of food and game
fishes of upland waters.
• About 50,000 fry collectors of Penaeus monodon in Sundarbans
simply destroy an average of 191 juveniles of other fishes for every fry
of their choice.
• For every tiger shrimp seed caught, an average of 318 other prawn
seeds, 8 fish seeds, 60 crab seeds, 1 mollusc seed and 13 unidentified
seeds, totalling 400 seeds are destroyed [Mahapatra et al. (1995)].

34. Exotic fish species
• Many alien species introduced have been found invasive and they have the ability
to establish themselves, invade, out-compete native species and take over the new
environments.
• Some risk sector are
1. ecological threats (pests and invasive),
2. general (hybridization with local species),
3. environmental (alteration in aquatic ecology),
4. introduction of exotic pathogens,
5. food safety and public health,
• Uncontrolled introduction of exotic fishes also exterminated the indigenous fishes
in some ecosystems. Common carp introduced into Kashmir valley has almost
exterminated the native Schizothoracine fishes in the Kashmir valley.

35. Overexploitation
• Over-fishing affects heritable life history parameters like growth and
age of sexual maturity.
• Over-exploitation of fishery resources due to its higher economic
value has exacerbated the vulnerability of the population in different
ecosystems.

36. Climate change
• Global climate change is likely to result in severe droughts and floods
with major impact on human health and food supplies, according to
the India’s report to the United Nations
• as per recent report, reduction in river discharge due to combined
effect of climate change and water withdrawal will make the up to
75% global freshwater fish biodiversity to become extinct by
2070 .
• There is need to intensify efforts for increasing climate literacy among
all stakeholders as well as farmers.

37. Conclusion
• Although the state and central government have already taken several measures to
conserve the fish biodiversity, but still it is not sufficient. More conservation
measures are needed for this purpose.
• Since the natural resources are undergoing drastic deterioration as a consequence
of anthropogenic changes, the conservation strategies must be innovative and
integrated.
• Success will depend on the extent to which conservationists, water commissions,
corporations, and municipalities work cooperatively in these places to maintain or
restore natural water habitats of the state.
• Moreover, there is need to improve knowledge on biodiversity by strengthening the
taxonomic capacity using computer, image analysis, and molecular tools etc.

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