Hooghly matlah estuary

HOOGHLY-MATLAH ESTUARINE FISHERY

Upama DasM.Sc. IF, 2nd SEM

RO-18SIF, CUSAT

INTRODUCTION• The river Ganges has an extensive estuarine system covering the

southern part of west bengal, and bangladesh. • The portion within the Indian territory in southern West Bengal

comprises the hooghly-matlah Estuarine complex. • The principal component of it. Viz., The river Hooghly runs a winding

course from its point of divergence from the parent river till it merges with the sea. On its way it receives river Rupnarayan, a major tributory alongwlth the rivers Saptamukhi, Thakuran, Matlah, Gosaba, Bidya. Hartnbhanga, Ichamati and Raimangal forming an estuarine Complex.

• The lower portion of this estuarine system, a network formed by the main channel. Its distributaries creeks, is known as the Sunderban delta.

• The rivers Saptamukhi, Thakuran, Matlah are now just inlets of tidal water with their upper connections lost due to siltation and neo-tectonic activities of 12th century.

GEOGRAPHICAL LOCATION 21⁰-23⁰ N LATITUDE 88-89⁰E LONGITUDE WEST BENGAL

Largest estuarine ecosystem in India, with an area 8029 km2

The Hooghly is a positive estuary in the mixo-haline range (pantutu, 1966). This estuarine system supports commercial fisheries of considerable value.

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

Hooghly estuary and its various fishing zones

DIFFERENT ZONES OF HOOGHLY-MATLAH ESTUARY

For estimating fish landings, CIFRI divided this estuarine system into the following zones:

Zone 1-Nabadwip to Konnagar (upper zone of the freshwater zone). Salinity- 0.011 to 0.036 ppt.

Zone 2- Konnagar to Diamond Harbour (middle zone of the hoogly estuary or the ‘gradient zone’). Salinity- 0.020 to 0.596 ppt.

Zone 3- Diamond Harbour to the mouth of the estuary including entire lower Sunderbans (lower or marine zone of the system). Salinity- 0.20 ppt to near neritic salinity.

Zone 4- Includes river Rupnarain. Salinity-0.043 to 1.025 ppt. Zone 5- Includes river Matlah around port canning.

PHYSICO-CHEMICAL PARAMETERS OF THE ESTUARY

Soil texture mostly clay silty loam

Temperature 16 0 C – 330 C

pH 7.8- 8.8Salinity 0.5- 32.5DO 4.8- 8.9

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

Fish species 172Molluscs 23

Crab 67Prawn 15Algae 150

Aquatic Biodiversity

TOTAL CATCH ( t ) from the HOOGHLY-MATLAH ESTUARINE SYSTEM

CATCHMonth-wise catch structure• Low catch during the summer months of March to June. • The catch begins to increase from July with the onset of

monsoon.• Reaches peak during winter months of November to January. • Maximum average catch (82%) was accounted during winter

months of November, December and January.• Minimum average catch (3.5%) was during the summer

months of March to June, leaving the rest i.e.,14.5% average catch for the monsoon months (July to October).

Average monthly landings (t) from the Hooghly-Matlah estuarine system

..CATCH zone-wise catch structure• As usual, most of the total annual catch (92 to

95%) comes from the lower estuarine zone (zone IIl), i.e., Diamond harbour to the mouth of the estuary including entire lower sunderbans (lower or marine zone of the system).• The upper estuary i.e., Zone I, II and IV

together contribute 5 to 8% of total annual catch.

ZONE-WISE ANNUAL CATCH (t) FROM THE HOOGHLY-MATLAHESTUARINE SYSTEM

SPECIES 1994-1995 1995-96 1996-97 1997-98 1998-99 1999-2000 AVERAGE (FROM 1994-95 TO 1999-2000) AVERAGE (FROM 1984-85 TO 1993-94Tenualosa ilisha 6.95 10.01 14.69 18.99 17.75 10.52 13.15 8.14

Liza tade 0.01Liza parsia 0.03 0.05 0.05 0.12 0.03 0.03 0.05 0.06

Lates calcarifer 0.2 0.5 0.1 0.47 0.17 0.03 0.24 0.1Sillaginopsis panijus 0.16 0.06 0.17 0.16 0.04 0.03 0.1 0.11

Polynemus paradiseus 0.4 0.63 0.59 0.61 0.65 0.58 0.58 0.56Eleutheronema tetradactylum 0.02 0.01 0.03 0.07 0.03 0.04 0.04 0.06

Polynemus indicus 0.07 0.21 0.14 0.28 0.17 0.16 0.17 0.33Coilia spp 3.95 2.45 2.82 2.73 4.16 3.38 3.25 2.39

Pama pama 12.92 10.99 12.02 8.36 10.04 12.3 11.11 11.99

Percentage composition of commercial species in the total catch from theHooghly-Matlah estuarine System.

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, Eeutheronema

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 : Scylla Serrata, Portunus Pelagicus

HlLSA CATCH ( t ) from the HOOGHLY-MATLAH ESTUARINE SYSTEM

FISHERY OF HILSA• The prime fish, hilsa forms commercially the most

important fishery of the estuary in view of its high market value. • Hilsa catch has increased from 1996-97 onwards

which may be ascribed to tremendous increase in effort in recent years coupled with enormous improvement of mechanization.

Season wise Hilsa catch (t) from Hooghly-Matlah estuary system

• Hilsa, winter migratory bagnet catch, forms the mainstay of the estuarine.

• Fish catch contributing 15 to 29% to the total annual fish landing.

• The monsoon (July to October) hilsa catch contributes 68% of the total annual landing of the species from the estuary.

• Dominance of large sized fishes in the length range of 23 to 53 cm representing 3rd, 4th and 5th year age group, is the striking feature of the monsoon hilsa fishery.

• The fishery in winter is of a smaller magnitude which contributes 26.5% of the total catch of the species.

• Hilsa juvenile (fry and fingerlings) constitute a major fishery during their downward migration in upper zone.

GEAR WISE COMPOSITION OF CATCH• Most of the gear are for multi species

exploitation, but some are selective for particular species.• Bagnets and drift gill nets constituted the most

dominant gears in the estuary accounting for 62 to 82% (average 73%) and 16 to 31%b(average 24%) respectively of the total catch with the rest contributing only 3% on the average.

WINTER BAGNET MIGRATORY FISHERY

• The total estimated winter bagnet fish landing fluctuated within 20820.6 to 35844.6 t per season with an average CPUE of 53.12 to 93.72 kg during the period 1994-95 to 1999-2000.

• Though the total catch of WMBF shows a rising trend upto the year 1996-97, the downward trend of overall average CPUE from 1995-96 is a warning signal indicative of over exploitation.

THREATS

Deteriorating ecological characters due to anthropogenic pressure

Overexploitation of faunal resources Destruction of mangroves Siltation and formation of sand bar Flood and shortage of fresh water discharge Hydraulic structure (dams, barrages, weirs) Wanton destruction of juvenile hilsa

SUNDARBAN FISHERY

FISH AND SHELL-FISH DIVERSITY

• A total of 156 fish species belonging to 53 families and 16 orders, were recorded;

• Gobiidae was the most common family with 20 species,

• followed by engraulidae (13 Species),• sciaenidae (11 species) and ariidae (8 species).

• Preliminary estimate of fish catch from winter bag net fishing, along the lower sundarban revealed a major shift in catch composition in comparison to landings during 2009-10.

..FISH AND SHELL-FISH DIVERSITY• Drastic reduction in landings of harpadon nehereus was recorded in current

year, which constituted 27.25% (9927 t) of total catch during 2009-10. • High landing of pony fish was recorded, which curently forms the most

dominant component of winter bag net fishery. During january 2016 it constituted 92% of the total catch.

• Non-penaeid prawns (mainly acetes spp.) Have emerged as one of the most dominant fishery resource.

• There is overall reduction in the catch of fin-fishes.• The fishery is presently dominated by prawns (58.5% as compared to

10.23% in 2009-10). • The bag net catches were dominated by invertebrates (73.5 %), comprising

prawns (58.5%), crabs (11.65%), stomatopods (2.10%) and cephalopods• (1.26%). • Atypopeneus stenodactylus, which was a rare component in prawn catches,

is now one of the major prawn species with relative abundance of 3% among the prawn landings.

Crab diversity and fisheries in Sundarban

Crab fishery resources of Sundarban are supported by marine, estuarine, brackish waterand freshwater species. During November 2015 to March 2016, 9 species of marine and estuarine crabs, belonging to seven genera and five families were recorded from selected stretches of Sundarban viz. Nischintapur, Patharpratima, Frazerganz, Jharkhali, Bally, Jatirampur and Pakhirala.

Scylla serrata represented the largest known edible and highly valued economic species of the Indo-Pacific region, both in domestic and international markets; marketed live. The professional crab fishers employ mainly four types of gears, viz., Sik or hook, don (suti) or baited line, Chakjaal (a trap) and monofilament nets with baits exclusively for capturing Scylla serrata in the deltaic Sundarban. Hence, Scylla serrata was found dominant in commercial catch in all the stretches of Sundarban. However, various types of nets are mainly used to catch fishes inthe estuary by the local fishermen, also to trap crabs as supplementary or by-catch. Such nets include bag nets, cast nets, Charpatajaal or set barrier net. Charybidis orientalis was most dominant (~79% of the total catch composition of crab) in the catch of bag net with size ranging from 0.5 cm to 2.5 cm followed by Matuta planipes (10%), Varunalitterata (7%), Scylla serrata (2%) and Philyra sps. (1%) as by-catch and these species do not have any commercial importance.

Reference

• CIFRI bulletins• CIFRI annual reports