Ravi KumarCIFE, MumbaiFRM-PA3-08

Biodiversity of Hooghly - Matlah Estuarine system

FRM- 601

Content Introduction Zonation Physico-chemical parameters Biodiversity Fishery resources Production Hilsa fishery Source of seed Threats Conclusion

Introduction Geographical location 21⁰-23⁰ N latitude 88-89⁰E longitude West Bengal

Largest estuarine ecosystem in India, with an area 8029 km2

• It forms world’s largest delta (sundarban), endowed with largest mangrove vegetation (4,264 km2)

Cont…

Distributary of the river Ganga

Positive, mixohaline in nature

Average tidal elevation is 5.7m

Different zonesFor estimating fish landings, CIFRI divided this

estuarine system into the following zones: zone 1-Nabadwip to Konnagar (upper zone of the freshwater

zone) Zone 2- Konnagar to Diamond harbour (middle zone of the

Hoogly estuary or the ‘gradient zone’) Zone 3- Diamond Harbour to the mouth of the estuary

including entire lower Sunderbans (lower or marine zone of the system)

Zone 4- includes river Rupnarain. Zone 5- includes river Matlah around port canning.

Physico-chemical parameters of the estuary

• Temperature and salinity are the most significant factors that determining the fishery.

• The maximum and minimum temperatures recorded in the pre-monsoon and post-monsoon respectively, in all zones except Zone 4 ,where the maximum temperature prevails during monsoon

Soil texture mostly clay silty loam

Temperature 16 0 C – 330 C

pH 7.8- 8.8

Salinity 0.5- 32.5

DO 4.8- 8.9

Fish species 172

Molluscs 23

Crab 67

Prawn 15

Algae 150

Aquatic Biodiversity

Fishery resources 172 species recorded,73- freshwater and 99 occupy the

saline zoneFish fauna classified into: - residents (mullets, threadfins, sciaenids, sea bass) - migratory or transient (Hilsa, Pama pama, pangasius,

rosenbergii)Dominated fish spp.

T. ilisha 51%

H. nehereus 11.3%

Pama pama 5.7%

Setipinna phasa 4.7%

Trichiurus spp. 4.2%

Penaeds prawn 4.35%

Cont…Other important fish species : Polynemus paradiseus, P.indicus, Eleutheronema

tetradectylum, Lates calcarifer, Pangasius pangasius, Liza parsia, L.tade, Rhinomugil corsula, Pampus argenteus ,Coilia dussumeiri, Mystus spp. , Johnius dussumeiri , Clupisoma garua, Wallago attu, Sperata seenghala, Ompok bimaculatus and Rita rita etc.

Prawns: Penaeus monodon, P. indicus, Metapenaeus brevicornis, M. monoceros ,Parapenaeopsis sculptilis, P. stylifera, Macrobrachium spp.

Crabs : S. serrata, P. pelagicus

Fish production The average annual prawn and fish yield increased from

3,204 t (1960-63) to 117,639 t in 2010-11.

Cont….

• Maximum average catch (82%) is obtained during winter months of Nov-Jan

• Minimum average catch (3.5%) is during the summer months of Mar-June

• Zone-wise total annual catch (92 to 95%) comes from Zone- Ill, while, Zone 1, II and IV together contribute 5 to 8% only

Hilsa fishery

The average hilsa production have been increased from 1427 t (1957-74) to 10,083t (2003-04)

About 80-90% hilsa are captured during July- Oct. The peak spawning period is noticed during Sep- Nov., although this species is

prolific spawner

Winter migratory Bag net fishery: The fishermen migrate to the lower zone of estuary and they remain engaged in fishing during the end of Oct. to middle of Feb. The total landing of this fishery with an avg. 28536.7 tones. This fishery contributed 60-65% of total yield of the estuary. The net used is locally known as been jal (a migratory bag net).

Source of seed• A potential source of cultivable fish and prawn seed which are

being used as stocking material for brackish water aquaculture

P. monodon (Bagda), P.indicus, Metapenaeus. monoceros, M. brevicornis, Liza spp. Lates calcarifer , M. rosenbergii, Hilsa etc.

Threats Deteriorating ecological characters due to anthropogenic

pressure Overexploitation of faunal resourcesDestruction of mangrovesSiltation and formation of sand barFlood and shortage of fresh water discharge Hydraulic structure (dams, barrages, weirs)wanton destruction of juvenile hilsa

Conclusion

• There is a urgent need to protect estuarine envt. From pollution hazards (Agri., Industrial. and Domestic effluents).

• Estuarine envt. should be judicially exploited so that the fish, prawn and their recruits are not destroyed

• Mangrove preservation• Intensive seed collection should be stopped

Thank you