The State of West Bengal supports a wide variety of wetlands covering freshwater, brackish water, and coastal wetlands, both natural and manmade wetlands. The Directorate of Fisheries, Government of West Bengal estimated at 3,111,92.52 ha which include river, canal, beel/ baor, and reservoir. A list of a total of 61 cultivated and culturable species occurring in freshwater and brackish water wetlands of West Bengal is provided. Another list of 21 crustacean fishery species occurring in coastal wetlands is added in this communication along with their local names, size, occurrence, and utilization from coastal areas of West Bengal. Export of a freshwater prawn species, Macrobrachium rosenbergi (De Man) and a brackish water prawn species, Penaeus monodon (Fabricius) are highlighted. It is suggested that relevant Government agencies, local administration, educational institutions, individual experts and NGOs need to act closely on various approaches and issues of mutual interest towards aquacultural development and better management of larger wetlands of West Bengal.

Keywords: impounded water areas, freshwater resources, fishery resources, cultivable species, introduced species, export items, West Bengal

Wetlands assume an extremely wide range of forms and include a wide spectrum of habitats. To layman wetlands are lands where people get their feet wet. In fact, wetlands are diverse assemblage of wet and watery habitats which share several common features of both aquatic and terrestrial ecosystems. Wetlands in the State of West Bengal in India comprise a unique assemblage of different and diversified types of fresh, brackish, and coastal wetlands. These wetlands are distributed under three major landforms, viz., Mountains and Hills, Highlands and Plateau, and Plains. These landforms can be fairly divided into eight physiographical units, such as, i) The Darjiling Himalaya, ii) The Terai Duars, iii) North Bengal Plains, iv) Western Rolling Uplands and Plateau, v) Rarh Plain, vi) The Ganga Delta Plain, vii) The Sundarban, and viii) The Sandy Coastal Plain. The geology, ecology, soil characteristics, climate, rainfall, drainage, natural vegetation, and human interferences interplay in defining diversity, distribution, and richness of faunal diversity including economically significant aquacultural fishery resources in this state of West Bengal.^1–12

West Bengal is in the geographical coordinates at 22° 32´ north latitude and 88° 44´ E longitude in India. According to the Directorate of Fisheries, Government of West Bengal, culturable, semi-derelict and derelict impounded water area encompasses a total of 295464.80 ha. The district-wise distribution of these waterbodies is shown in Table 1.

Freshwater wetlands

The district-wise distribution of freshwater resources is presented in Figures 1 & 2 and Table 2. It is evident that highest and lowest running water resource is in the districts of Murshidabad (36,283.23 ha.) and Haora (1007.36 ha.) respectively while highest and lowest standing water resource is in North and South 24-Parganas (26,815.13 ha.) and Medinipur (404.1 ha.) respectively. The table, however, does not reflect figure for Kolkata but it is estimated that there are about 220.00 ha. of water bodies which have been frequently surveyed by researchers of the Zoological Survey of India, universities, and other institutes.

Figure 1 Map of West Bengal showing 19 districts (now 23 districts).

Figure 2 Physical map of West Bengal showing river systems.

Brackish water wetlands

According to Central Marine Fisheries research Institute, Cochin, brackish water wetlands of India extend over 1.19 million ha of which 0.88 million ha are under culture distributed within ten maritime states / union territories. Of these, West Bengal has a total brackish water wetlands area of 4,05,000 ha of which 33,918 ha are under culture. These wetlands are in three districts (East Medinipur, North 24-Parganas and South 24-Parganas) of West Bengal. Saha et al.¹³ made an inventory survey of brackish water bheries of undivided 24-Parganas district which reveals that there were 1334 brackish water bheries covering an area of 32929.56 ha under three saline zones viz., low saline zone, below 10 ppt (387 bheries of 9844.11 ha, ranging 2-200 ha), medium saline zone, 10-20 ppt (458 bheries of 15613.25 ha, ranging 2-267 ha) and high saline zone, above 20 ppt (489 bheries of 7472.20 ha, ranging 2-120 ha). More than 90% of the first two categories are seasonal bheries, while more than 90% of the third high saline ones are perennial.

Nandi et al.,⁴ had made an inventory of wetland faunal resources of West Bengal, comprising 2928 species under 23 phyla including 331 endemic species belonging to 14 phyla. Herein, an attempt is made to evaluate the cultivated and culturable aquatic animal species occurring in wetlands of West Bengal. A total of sixty-one animal species has been listed from both freshwater and brackish water wetlands of West Bengal (Table 3). Most of these species are endogenous, while some are exotic species. Eight exotic fish species are widely cultivated in this State. Two coastal crustacean species are included under items of export such as the highly priced tiger prawn Penaeus mondon (Fabricius) and the mud crab, Scylla serrata (Forskal) which are exported frozen, canned, or alive from West Bengal.

Introduced fish species

Introduction of exotic fish species in West Bengal wetlands include several species of fishes, viz., tilapias (Oreochromis mossambica (Peters) and O. niloticus niloticus (Linnaeus), silver carp (Hypothalmichthys molitrix (Valenciennes), grass carp (Ctenopharyngodon idella (Valenciennes), cyprinus carp (Cyprinus carpio carpio Linnaeus), gouramy (Osphromenus goramy Lacepede), bighead carp (Hypothalamichthys nobilis (Richardson), etc. These fishes are introduced in the country from Africa, Europe, and other parts of the world. The Gold fish, Carassius auratus auratus (Linnaeus) and C. carassius (Linnaeus), have been introduced in India as well as West Bengal as aquarium pet from China, Korea, Japan Taiwan, Europe, Siberia, East Asia, Vietnam.

In coastal wetlands of West Bengal crustacean fishery resources are rich the inshore coast including estuaries and mangroves.^3,6 The commercially important crustacean fishery resources are listed in Table 4. A list of economic species of fishes, prawns and crabs occurring in coastal and estuarine waters of Sundarban, West Bengal has been listed by Pramanik and Nandi⁶ which include 15 species of cartilaginous fish, 119 species of bony fish, 4 species of stomatopods, 16 species of prawns, 10 species of crabs and 3 species of molluscs. The commercially exploited prawns and shrimps consist of 21 species, amongst which penaeids form the bulk of the catch contributing to more than 50% of the total production. Metapenaeus brevicornis (H. Milne-Edwards) is abundant in inundated brackish water and in low lying paddy fields during and after rains. Metapenaeus monoceros (Fabricius) and M. lysianasa (DeMan) occur plentifully in estuaries and brackish waters of Ganga delta. Penaeus semisulcatus De Haan is abundant all over the deltaic region and is the commonest naturally occurring large sized penaeid prawn of West Bengal. This species is usually found in freshwater but it can withstand brackish water to some extent and occurs extensively in rivers, canals, beels and tanks of coastal West Bengal. It grows to more than 30.0 cm in length. The weight of a single specimen may exceed even 500 gm (Table 4).¹⁴

Export items

Amongst the crustacean export items, a freshwater prawn species, Macrobrachium rosenbergi (De Man) and a brackish water prawn species, Penaeus monodon (Fabricius) are highly priced. Penaeus monodon (Fabricius) locally known as “bagda” is often referred to as the “living dollars” of Sundarban coast. This prawn species is extensively cultured in the coastal districts of the State. Large number of men, women, and children (well over 50,000) are engaged in the collection of “bagda” seed from coastal waters and estuaries throughout the coastal belt of this State. The juveniles of this species are reared in pools and brackish water bheries of the Ganga delta. Two palaemonid species, Exopalaemon styliferus (H. Milne-Edwards) and Nematopalaemon taenuipes (Henderson) occur in abundance and support important fisheries in the deltatic areas of Sundarban. Large quantities of these two species are landed and sold for domestic consumption and export. In the last three decades, crabs have emerged as an important commodity of export. Among the crab species, only two species, namely, Scylla serrata (Forskål) and S. tranquibarica (Fabricius) are highly valued and have entered export markets from West Bengal coast. Item-wise marine product export is presented in Table 5.

The State of West Bengal supports a rich commercially important finfishes and shellfish species. People particularly user groups and stakeholders need to know the values of local wetlands and how to protect, preserve and promote their values minimizing encroachment and threats. Towards this goal the quantity and quality of information on local wetlands, their economic values be increasingly understood and communicated. Relevant Government agencies should collaborate closely with educational institutions, individual experts as well as NGOs on issues of mutual interest, so that wetland conservation, aquacultural development, and appropriate management are achieved. It is desirable that the wisdom and ideas of knowledgeable representatives of the local panchayats and Fishermen cooperatives are heard and incorporated in future policies and plans for local larger wetlands. Furthermore, economic incentives, measures to strengthen local control over resources and more effective management practices be targeted prioritizing the fishery production of larger wetlands. To facilitate this, essential information needs to be made available to the local Land and Revenue departments as well as Fisheries departments concerned.

None.

The author declares no conflict of interest.

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