Available online a t www.pelagiaresearchlibrary.com Pelagia Research Library Advances in Applied Science Research, 2012, 3 (4):2337-2345 ISSN: 0976-8610 CODEN (USA): AASRFC Assessment of fishery resources in relation to some physico-chemical parameter of water in Sundarbans Mangrove Ecosystem, India Sunirmal Giri* and Susanta Kumar Chakraborty** *Department of Zoology, Belda College, Belda, Paschim Medinipur, West Bengal, India **Department of Zoology. Vidyasagar University, Midnapore, West Bengal, India _____________________________________________________________________________________________ ABSTRACT The Sundarbans comprising of Hoogli- Matla estuarine system offers an excellent eco-zones for several finfish and shellfish species as it provides physiologically suitable environment with respect to different physicochemical parameters and abundant supply of nutrients to the aquatic subsystem in the form of detritus exported from the adjoining mangrove forest subsystem. The present study has been conducted during November, 2001 to October, 2003 in order to assess the diversity of the fishery resources and also to study the feasibility of sustainable development of culture and capture fishery along this coastal belt. So far, 118 fin fishes ,24 shrimp species and 4 species of crabs have been recorded form different parts of Sundarbans Biosphere Reserve. Information relating to fish landings (weight / month) collected from different fish landing centres along the stretch of this environment were also recorded in the present study. Physicochemical parameters like Temperature, pH, DO, BOD, Light penetration, Turbidity, Salinity, TDS, TSS, Nitrate nitrogen, Phosphate phosphorus and Silicate have been estimated to understand the seasonal dynamics of this mangrove ecosystem and also to assess whether these parameters have any role in determining fish resources availability. Key words: Fishery resource, Fish landing, physicochemical parameters, Sundarbans. _____________________________________________________________________________________________ INTRODUCTION Mangroves are defined as those ecosystems of the intertidal tropical and subtropical zones dominated by woody halophytes, with interconnecting water courses, swamps and backwaters as well as their associated populations of plants and animals [1]. The intertidal salt tolerant halophytic vegetation constituting the main structural component of mangrove ecosystem experience the influence of two high tides and two low tides a day. The Hoogli-Matla esturine system representing the largest one in India, covering a major portion of the Ganga- Brahmaputra deltaic complex and circumscribes marshy area called Sundarbans known for its largest mangrove forest in the country. This region is rich in faunistic resources and forms the mainstay of the capture fisheries of India. This estuarine system, particularly its lower zone, sustains important multi-species commercial fisheries exploited by multi gears. A large number of fishermen in groups of fishing parties migrate from different areas of Midnapore District, 24- Parganas District and other parts of the adjacent areas to different mangrove-deltaic island of Sundarbans in order to during winter seasons and establish temporary fishing camps and also to remain engaged in fishing during winter months (from October to February). The temporary fishing camps are locally named as 'khuties'. The present study has been conducted to assess the diversity of the finfish and shellfish species and also to scan information on fish landings collected from the different landing centres . Different physico-chemical parameters have also been estimated to understand the seasonal dynamics of this environment and also to gain an idea about the role of ecological factors in governing the distribution of different fishery resources. Study sites The Indian Sundarbans are located between 21 032 / - 22 040 / north and between 88 085 /–89 000 / east, mainly within the 24 – Parganas district of the state of West Bengal (Fig-1). It lies at the apex of Bay of Bengal and the entire area is 2337 Pelagia Research Library Sunirmal Giri et al Adv. Appl. Sci. Res., 2012, 3(4):2337-2345 _____________________________________________________________________________ criss-crossed by a number of estuaries viz. Hoogli, Muriganga , Saptamukhi , Thakuran , Gossaba , Vidya , Matla and Harinbhanga etc. knows as Hoogli –Matla estuarine complex along with their tributaries and creeks of varying depths and widths, forming a good number of deltaic islands. The Mangrove forest of Indian Sundarbans have been variously estimated as 418,888 hectors [2&3] and as 426,300 hectors by the forest department of West Bengal. For estimating physico-chemical parameters of water, 4 sampling sites viz. Bokkhali and Frezerganj on Hoogli estuary, Susnirchara on Saptamukhi estuary, Canning , Bhagankhali and Jharkhali on Matla estuary -the 3 major estuaries of Sundarbans have been selected. Among these estuaries, Matla is situated in the South East part of Sundarbans while two others are located on Central and South -West parts of Sundarbans and for the estimation of fish landings, three sampling sites have been selected ( viz. Frezerganj, Canning and Diamond Harbour) as these are the main three landing centre of Sundarbans. MATERIALS AND METHODS The study was conducted during November, 2001 to October, 2003. Monthly samplings of water were collected from the study sites and were analysed following standard methods [4-7]. Faunal components were collected and subsequently identified with the help of standard literatures [8-9]. Fishes were collected both from the intertidal belts as well as from the open water bodies with the help of different crafts (like - Dinghi, Nouka, nonmechnised and mechanised boats etc) and gears (like bag nets, gill nets, drag nets etc.). Fishermen inhabiting in the island were supplied with plastic containers and preservatives (5% buffered formalin) for keeping token sample of fishes, shrimps and crabs from their daily catch which were subsequently collected and identified. Information pertaining to total fish catch were collected by direct observation as well as in consultation with the fishermen in every month. RESULTS AND DISCUSSION All total 118 finfish species belonging to 83 genera, 43 families and 8 order have been documented during the study period ( Table-1). Maximum number of species belong to order perciformes followed by clupeiformes and siluriformes. 24 species of shrimps belonging to 7 genera, 4 families and 1 order have been recorded. 4 species of crabs belonging to 3 genera, 1 family and 1 order have also been recorded ( Table-2). Total estimated catch from the study sites during the period of November, 2001 to October, 2003 were 3830072 kg , 2851527.6 kg and 7313224.4 in Diamond Harbour , Canning and Frezerganj respectively( Table 3-5) which revealed that maximum landing was contributed by Frezerganj followed by Diamaod Harbour and Canning landing centre. Out of 118 fin fish species recorded in the present study, 23 species were recognised as commercially important fin fishes besides 4 species of shrimps and 2 species of crabs. The species wise catch showed that the bulk catch comprised of Harpadon nehareus, Pama pama, Setipinna spp., Trichiurus spp., Tachysurus jell, Coilia spp., Sciaena spp., Lutjanus spp., Anodontostoma spp. Liza parsia ,Lates calcarifer, Pampus argentius, , Ilisha magaloptera and Tenualosa ilisha. The fisheries aspect of the aforesaid aquatic resources have been studied in details by many workers [10-13]. Pantulu ,1966 [14] classified the fish fauna of Hoogli- Matla estuaries into two categories i.e. residents and migrants. In general the fish fauna can be broadly classified into following categories-i) marine species which used to migrate from upstream and spawn in less saline water region of the estuary viz. Tenualosa ilisha, Polynemus paradiseus, Sillago sihama , Pama pama and Penaeus monodon ; ii ) fresh water species which spawn in saline areas viz. Pangasius pangasius , Anguilla sp, Macrobrachium rosenbergii , iii ) marine forms which used to visit high saline zone of the estuary for breeding viz. Tachysurus jella, Osteogeniosus militaris Eleutheronema tatradactylum etc . During winter season, a calm weather prevailing in the extreme lower stretches of the estuary very close to the sea provided favourable condition for the operation of stationary bag nets. Such favourable condition prevailed till the onset of south west wind which started about the middle of February and converted the weather very rough and non-conducive for the operation of these nets. Not only this, the availability of fish vulnerable to bag nets at these fishing zones during November to January ranged from about fifteen to thirty times more than the average availability at the upper estuary throughout the year. A wide variety of gears were used by the fishermen viz. trawl nets, seine nets (small and big) drift gill net, set gill nets, cast nets, bag nets, hooks and lines. The most priced species of this estuary is Tenualosa ilisha amongst the clupeids; Liza parsia and Liza tade are amongst the mullets, Eleutheronema tetradactylum , Polunemus indicus are amongst the polynemids , Lates calcarifer amongst the perches, Penaeus monodon , P.indicus Metapenaeus monoceros, M. brevicornis , Accetes indicus etc amongst shrimps, Scylla serrata and Portunus pelegicus are amongst crabs . Besides, Pampus argenteus also enjoys good market value. The catch landed during winter