International Journal of Ecology and Environmental Sciences 37 (4): 157-218, 2011 © NATIONAL INSTITUTE OF ECOLOGY, NEW DELHI

Strategies for Sustainable Fisheries in the Indian Part of the GangaBrahmaputra River Basins K.K. VASS$ , MANAS K. DAS , R.K. TYAGI, PRADEEP K. KATIHA , S. SAM ANTA , N.P. SHRIVASTAVA , B.K. BHATTACHARJYA , V.R.SURESH , V. PATHAK , GANESH CHANDRA , D. DEBNATH AND BRIJ GOPAL * Central Inland Fisheries Research Institute, Barrackpore, Kolkata 700 120, India * Centre for Inland Waters in South Asia, 41 B Shiv Shakti Nagar, Jaipur 302017, India $ Corresponding author; Present address: C-218, Pocket-VII, Kendriya Vihar-II, Sector-82, NOIDA, U.P.; Email: [email protected]

ABSTRACT Riverine fisheries are of particular importance in the tropical regions as they provide food and nutrition to millions of people and support their livelihood. However, ever-increasing, multiple demands on water for irrigated agriculture, domestic and industrial supplies and hydropower generation have greatly impacted upon the river flows and riverine habitats and consequently the fisheries and riverine-fish-dependent communities. Other anthropogenic activities such as deforestation, mining, urbanisation and various flood control measures have further degraded the river ecosystems. Yet, little attention is paid to the fisheries and issues of conservation and sustainability of riverine ecosystems which contribute significantly to the food security and economy of the people. Three major Himalayan rivers - Indus, Ganga and Brahmaputra - are of greatest importance the Indian subcontinent as their drainage basins lie in China, India, Pakistan, Nepal, Bhutan and Bangladesh, cover nearly two-thirds of the subcontinent and are among the most densely populated regions of the world. Of these, Ganga and Brahmaputra, drain 26.2% and 5.9% respectively, of the total Indian territory, and join (together with another river, Meghna) in their lower reaches within Bangladesh before forming the world's largest delta and supporting the single largest patch of mangroves, the Sundarbans. The Ganga and Brahmaputra basins are sometimes treated as sub-basins of the combined Ganga-Brahmaputra-Meghna (GBM) basin. We review here the state of two major Himalayan rivers of India, Rivers Ganga and Brahmaputra, with reference to their fisheries, summarise various threats to them and discuss strategies for their sustainable management in the context of current policies, laws and institutional arrangements. Physiographically, the Ganga river is divisible into Upland reaches (from sources at 4100 m altitude to Rishikesh at 360 m; gradient 1:67; and equivalent range of its northern tributaries), Upper plains (from Rishikesh to Allahabad (58 m altitude; gradient 1:4100), Middle plains (from Allahabad to Farakka (19 m altitude; gradient 1:13000) and Lower plains (the delta in India and Bangladesh, which includes the Sundarbans and an extensive floodplain). River Ganga in the upper stretch has a vast catchment formed by River Yamuna and its tributaries joining it from the south, and the many tributaries originating in the Central Himalaya. River Brahmaputra has more than one-third of its catchment within India where it receives a large number of tributaries on its both banks. The upper reaches flow through mountain ranges and narrow valleys but later the river forms extensive floodplains. The Ganga and Brahmaputra basins experience a monsoonal climate that exhibits extremes of spatial and temporal variability in temperature (sub-freezing to nearly 50 ºC) and precipitation (10 cm in westernmost parts to >500 cm in the east). About 80% of rainfall occurs during the monsoon months (June to September) and this is reflected in the discharge of the two rivers and their tributaries that increases up to 100 times its dry season values. The two rivers are also unique in carrying huge sediment loads that are among the highest in the world. Both Ganga and Brahmaputra are rich in their fisheries (265 species in Ganga and 167 species in Brahmaputra that include both freshwater and estuarine species). River reaches vary greatly in the proportion of species they contain; the Alaknanda has the lowest number of species (41). The upper stretches of the two rivers (up to Haridwar in river Ganga and Pasighat in river Brahmaputra) support Mahseers, carps, snow trouts and catfishes. Commercial fisheries in both the rivers assume importance in the middle and lower stretches. Over the years, drastic decline in fish catch from the rivers has adversely impacted the livelihoods of landless fishers; they simply fish poverty every time they go to river to catch fish. This situation has been caused also by factors other than the fishery in these river systems. Although the flows of River Ganga and its tributary Yamuna had been diverted soon after their descent on to the plains more than a century ago, intensive river regulation has occurred in the post-Independent India. Numerous dams and barrages have been constructed over all tributaries, and their large stretches have been channelised by embankments. Numerous hydel projects have

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come up throughout the mountain stretches and many more are in different stages of development. Thus, both longitudinal and lateral connectivity of the rivers has been greatly lost and the migration of the fishes to their breeding and feeding sites has been obstructed. These changes have resulted in significant decline of fisheries, particularly the the cold water fishes (snow trout and mahseers) in the upper stretches and Indian major carps (IMC) in the plains. Among the more prominent and well known effects has been that of the Farakka barrage on river Ganga shortly before it enters Bangladesh. While the Indian shad, Tenualosa ilisha has declined almost completely upstream of the Farakka barrage, the fisheries downstream have increased several fold. Increased deforestation in the upper catchment basins of rivers is also having an adverse effect on water quality through increased siltation and alteration of river regimes with increased runoff during the rains and reduced flow during dryer periods. Besides extensive alteration of flow regimes and the loss of floodplain habitats, the rivers have been severely impacted by excessive discharge of untreated or only partly treated domestic sewage and industrial effluents all along their course. Climate change is projected to stress the fisheries further with the melting of glaciers, rise in water temperature, alteration of flow regimes, extreme events like flood and drought, and change in water demands for other uses. Conservation and sustainable management of fisheries must be based on natural recruitment by protecting the micro- and macro-habitats of different fishes for their breeding, spawning, feeding and refuge. Maintenance of environmental flows is urgently required in the affected reaches. Further, management for sustainable fishery in the Ganga-Brahmaputra river system requires effective networking of the multiple stakeholders through appropriate institutional arrangements for development, implementation, policy and planning of management of fish stock, production, marketing and distribution. There is a strong need to involve all basin states of India to evolve policies on water and biological resources of the rivers. Cooperation between India and Nepal in the management of the migratory stock of Mahseer and between India and Bangladesh in the management of Hilsa is also needed. It is hoped that the recently constituted Ganga River Basin Authority in India will address some of these issues to achieve the objective of sustainable fisheries in future. Key Words: Beels, Climate Change, Coldwater Fishery, Dams and Barrages, Embankments, Environmental Flows, Fisheries Decline, Floodplain, Hilsa, Livelihoods, Pollution, Sediments, Socio-Economics of Fishers

INTRODUCTION Rivers play a major role in the economy of a country by sustaining agriculture, industry, domestic water supplies and energy and by providing biological resources. Riverine fisheries, especially those in the tropical regions, provide a range of benefits including food, nutrition and livelihoods for millions of people. National policies related to economic development, poverty alleviation, food security, conservation and sustainability, however, often fail to recognize their importance. At the same time, humans have grossly abused the rivers by extensive regulation of flows, habitat alteration, disposal of all kinds of wastes into them, and large-scale encroachments into their space. The impacts of these activities are already noticed in declining fisheries, increasing incidence of floods, lowered groundwater tables and growing incidence of water-borne diseases. Conservation and restoration of rivers have become vital and urgent for the overall sustainable development of a region. Three major rivers of the Indian mainland - Indus, Ganga and Brahmaputra - together with their many tributaries, originate in the Himalaya. Their basins cover nearly two-thirds of the Indian subcontinent and are shared by India’s neighbouring countries (China, Nepal, Pakistan and Bangladesh).The three river basins are also

among the most densely populated regions of the world where human activities have influenced the landscape for several millennia. These rivers have played a major role in shaping the history of human civilzation in the subcontinent (Gopal 2000). The basins of Ganga and Brahmaputra are generally considered together because they join together in their lower reaches in Bangladesh before forming the extensive delta. In fact, another River Meghna, which arises n the hills of northeast Iindia, also joins them further downstream within Bangladesh, and hence, the basin is also referred to as Ganga-Brahmaputra-Meghna (GBM) basin. Rivers Ganga, which drains about 37% of the Indian mainland) and Brahmaputra form extensive floodplains and a delta that ranks among the largest in the world. They have hosted a very high diversity of freshwater fish and supported extensive fisheries on which depend the economy and livelihoods of millions of people - both fishers and non-fishers. In recent decades there has been a sharp decline in the fisheries from Ganga, caused by both exogenous and local factors. Similarly, River Brahmaputra, the lifeline of the people in the northeast Indian states, also supports a large fish-dependent community but the fisheries are on a decline. There exists a vast amount of published literature on various aspects of the two river systems and their

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fisheries as well as the recent human impacts and management issues. In this review, we summarise the fisheries resources of the two river basins within India, analyse various threats to them, and then examine the social, institutional and legal framework before discussing the strategies for their rehabilitation and conservation. The salient features of the two river systems, as far as these are concerned with the fisheries, are described only briefly.

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mountains, hills and plateaus intersected by valleys and river plains. They are largely covered by forests. Aravali uplands, Bundelkhand upland, Malwa plateau, Vindhyan ranges and Narmada valley lie in this region. Predominant soil types found in the basin are sandy, loamy, clay and their combinations such as sandy loam, loam, silty clay loam and loamy sand soils. The cultivable area of Ganga basin is about 57.96 Mha representing 29.5% of India’s total cultivable area. Climate

RIVER GANGA BASIN 2

The Ganga basin extends over an area of 1,086,000 km of which 861,404 km2 lies within India covering about 26.2% of its total geographical area. The rest of the basin extends into Tibet (China), Nepal and Bangladesh. The basin is bounded by the Himalaya on the north, Aravallis and the ridge separating it from Indus basin on the west, Vindhyan and Chhotanagpur plateaus on the south, and the Brahmaputra ridge on the east. The basin lies in seven States and the National Capital Territory of Delhi (Table 1).

Table 1. Area of Ganga river basin in different States

State

Uttar Pradesh Madhya Pradesh Bihar Rajasthan West Bengal Haryana Himachal Pradesh U.T. of Delhi

Drainage area (km2)

% of Indian Part

294364 198962 143961 112490 71485 34341 4317 1484

34.17 23.10 16.71 13.06 8.30 3.98 0.50 0.26

Physiography The main physical sub-divisions are the Northern Mountains, the Gangetic Plains and the Central Highlands. Northern Mountains comprises the Himalayan ranges including their foot hills. The Gangetic plains, situated between the Himalayas and the Deccan plateau, constitute the most fertile plains of the basin ideally suited for intensive cultivation. The Central highlands lying to the south of the Great plains consists of

Annual rainfall in the Ganga basin ranges from 250 to 4000 mm. The monsoon climate is characterized by dry summer, with very little rain. The southwest monsoon arrives over Bangladesh in early June and gradually moves westwards. The whole lower Ganga basin receives heavy rainfall. In the middle Ganga basin, monsoon sets in by the middle of June and the upper Ganga basin generally starts receiving rain by the end of June. The total rainfall decreases westwards, from 800 to 1,200 mm in the plains in the middle basin, and 400800 mm in the plains in the upper basin. In the Lower Basin, three seasons are generally recognized: monsoon (June-October); winter (November-February); and summer (March-May). Although the monsoon months are remarkably wet, the winter months are suddenly very dry. Rainfall in these four months averages only about 100 mm. Winter rainfall in the Ganga Basin is due to the retreat of the southwest monsoon. This retreat is gradual in the Upper Basin, a striking contrast to the sudden burst when it arrives. By early September, the monsoon season is over in the Delhi area (Upper Ganga Basin), and by late September it is over even in Patna in the Middle Basin. While the last of the southwest (summer) monsoon still brings showers in the Lower Basin, the drier northeast (winter) monsoon winds begin to blow in the Upper Basin. By the middle of October, the Lower Basin is subjected to dry continental air and the summer monsoon rain ceases. Potential evapo-transpiration rates are about 1,500 mm, exceeding the rainfall rates from November to May. The relative humidity is high, varying from 70% in March to 89% in July. The area experiences moderate to long periods of sunshine, with over 8.5 hours outside the monsoon season being common. The mean annual temperature is 26°C with peaks of over 30°C in May. Winter temperatures can fall to 10°C in January. More than 450 million people live in the basin with an average density of over 550 per km2 which in some

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Figure 1. Ganga river basin in India. Dams, barrages and canals are also shown.

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localities and particularly in the delta, rises over 900 per km2 . Among the three riparian countries, India contributes more than two-thirds to the basin’s total human population. The basin countries are largely rural; India with slightly lower percentage of rural population (72%) than Bangladesh (74%).

THE RIVER GANGA River Ganga originates as Bhagirathi from Gangotri glacier at Gomukh at an altitude of 4100 m in the Garhwal Himalaya, and is joined by the Alaknanda, originating from Alkapuri glacier near Badrinath, at Dev Prayag (520 m altitude) where it attains its name, Ganga. The river Ganga flows southwest for about 80 km before turning south to descend on to the plains at Rishikesh. Thereafter, R. Ganga flows south and gradually turns eastwards meandering across the plain on its 2000 km journey to Farakka, close to the border with Bangladesh. At Farakka, the river turns south and after about 40 km, divides into two main channels: the smaller of these, again named as Bhagirathi, flows southwards through the Indian territory in West Bengal, and the other larger one, now known as Padma, flows further eastwards into Bangladesh where it meets the River Brahmputra (named Jamuna in Bangladesh) and further downstream joins the river Meghna ( River Barak in India). The combined rivers, Ganga-Brahmaputra-Meghna, forming an extensive delta (Figure 1). The Bhagirathi flows 513 km southwards to discharge into the Bay of Bengal near Sagar island. Almost in the middle of its course, near Nabadweep, it is joined by two small streams, Jalangi and Churni. The lower 190-km reach in the tidal zone is called as R. Hooghly (= R. Hugli), Hooghly is a funnel shaped estuary. At its mouth, it is 25 km wide with a cross sectional area of 156,250 m2 but is only 6 km wide (cross sectional area 36799 m2 ) at the landward end (Mukhopadhyay 2007). The estuary has an averge depth of 6 m and maximum depth of only 20 m. The tidal mixing zone of the estuary extends up to Diamond Harbour, about 80 km upstream. At its mouth, Sagar Island bifurcates the estuary into two channels: the western channel is retained as Hooghly and the eastern channel is named as Mooriganga. During its sojourn in the plains, R. Ganga is joined from both sides, by many tributaries which arise in the Himalaya in the north as well as by tributaries arising in the hills on the south. These rivers are described below in another section.

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Payne et al. (2004) divided the River Ganga basin into four physical sections for the purpose of discussion on fisheries. These are (a) Upland reaches: from sources at 4100 m altitude to Rishikesh at 360 m above sea level. This includes Bhagirathi and Alaknanda rivers. The average gradient is 1:67. Also included are equivalent ranges of northern tributaries to a point where they enter the Ganga plain. (b) Upper plains: from Rishikesh to Allahabad (58 m abpove sea level) with a mean gradient 1:4100. (c) Middle plains: From Allahabad to Farakka (19 m above sea level) through the lowlands of Uttar Pradesh, Bihar and West Bengal, with fringing floodplains, including the large floodable area of Bihar where Kosi joins the main river; mean gradient 1:13000; and (d) Lower plains: the delta in India and Bangladesh, which includes the Sundarbans and an extensive floodplain. Geomorphology River Ganga has high geomorphic diversity caused by variability in fluvial processes. The rivers are dominantly aggradational in the Eastern Ganga Plains (EGP) and degradational in the Western Ganga Plains (WGP). River Ganga around Kanpur and R. Yamuna around Kalpi in the WGP are examples of incised reaches. The overall topography in the surrounding region is also of degradational nature. All smaller rivers in the WGP are also incised, and in some areas, a strong development of dissected topography is manifested as badlands. On the other hand, the rivers of north Bihar in the EGP such as Gandak, Kosi, Burhi Gandak and Baghmati, exhibit aggradational morphology. These rivers are characterized by shallow and wide channels. The Gangetic rivers drain through a distinct rainfall gradient from west to the east whereby the western parts receive less rainfall (60 to 140 cm) than the eastern parts (90 to >160 cm), both in the hinterland and the alluvial plains. Further, the northern part of plains receives more rainfall than the southern part. The amount and distribution of rainfall in space and in time directly control the discharge variability in rivers throughout the year but particularly during the monsoon months. River Discharge and Sediment Load The river Ganga carries a total annual runoff of 21,400 million m3 at Haridwar (about 280 km downstream from the origin). Three fourth of this runoff occurs during the monsoon period (June to September). The flow of the

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river at Haridwar ranges from 1500 m3 s-1 during monsoon to 200 m3 s-1 in winter (Dasgupta 1984). In the middle stretch, flood discharge at Mokama (1830 km from origin) ranges from 30,000 to 75000 m3 s-1 (Godbole 1986 and Pandey 1980). The mean discharge from January 1965 through December 1973 at Farakka Barrage was 11,558 m3 s-1 (range = 1,181-65,072 m3 s-1 ) with the lowest discharge recorded from February through May and the highest from July through October (Vorosmarty et al. 1998). The rivers of the Ganga system originate in mountain ranges that are geologically young and comprise of unconsolidated sedimentary rocks and hence, are highly prone to erosion (Subramanian 1979; Subramanian et al. 1987). These features together with high water discharge contribute to high sediment supply from the tributaries. River Kosi, a major tributary of the Ganga, carries an annual load of 2,774 Mg (= megagram, ton) suspended silt km-2 (Holeman 1968, cited by IUCN 1980). The annual flow of the Ganga (468.7 x 109 m3 ) represents 25.2% of India’s total water resources (Gopal, 2000). The annual sediment load discharged by the Ganga system into the sea is 329 x 109 Mg (Chandramohan et al. 2001). Tributaries of Rive Ganga In the plains, River Ganga is joined by many tributaries. Their length, basin area and annual discharge are given in Table 2 and a brief description follows below. Garhwal Himalayan System The Garhwal Himalayan system comprises of rivers Ganga, Yamuna and Ramganga. The Ganga system may be divided into three subsystems: Alaknanda sub-system, Bhagirathi sub-system and Nayar sub-system. Alaknanda is the main river of the system and originates from Alkapuri glacier (Devtal). The Saraswati also originates at Devtal and meets Alaknanda about 3 km north of Badrinath temple. Dhauliganga originates from Kuling in Niti and meets Alaknanda at Vishnuprayag. Girthiganga and the Rishiganga are the main tributaries of Dhauliganga. The other important tributaries of Alaknanda are Birahiganga, Nandakini and Mandakini. Major part of the Uttarkashi and Tehri districts is drained by the Bhagirathi sub-system. The Bhagirathi originates from the Gomukh and its first tributary, river Janhavi, meets it at Bhaironghati. The Barigun Gad and Chor Gad are the main tributaries of Janhavi. Finally, it meets Alaknanda at Deopryag to form the Ganga. The

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only sizeable tributary of Bhagirathi is Bhilganga, which meets at Ganeshprayag, near Tehri with Alaknanda. Important tributaries of Bhilganga are Balkhila, Dharamganga, Chanjigad and Nalichami. The Jalandhari Gad, Siya Gad, Pilang Gad, Dhaneri, Nagun Gad and Jalkar river are other important tributaries of Bhagirathi. The Nayar sub-sytem, consisting two branches, the western and the eastern Nayar, is a compact sytem of drainage which drains most part of the Garhwal district. Both the rivers rise in the Dudhatoli range. Finally, both of them meet at Bhatkoli, near Satpuli and the united stream further 32 km downstream meets Ganga near Vyasghat.

Table 2. Length (km), basin area (km2 ) and average annual discharge (Mm3 ) of the tributaries of Ganga

Tributary 1. Ramganga 2. Yamuna 3. Chambal 4. Sind 5. Betwa 6. Ken 7. Gomati 8. Ghaghara 9. Gandak 10. Kosi 11. Tons 12. Son 13. Damodar 14. Kasai-Haldi

Length

Basin Area

Discharge

596 1376 965 415 590 360 940 1080 300 729 264 784 541 270

32493 366223 139468 25085 45580 28224 30437 57600 7620 11000 16860 71259 25820 10210

15620 93020 30050 7100 10000 11300 7390 94400 52200 16560 5190 26200 12210 5300

Yamuna System There are two main rivers of the system, viz., Yamuna and Tons. R. Yamuna originates from Yamnotri glacier which lies on the southwestern slope of the Bandar Punch peak. The Badri Gad and Aglar Gad are the two important tributaries of Yamuna in Tehri district. The Tons, the biggest tributary of the Yamuna in the Himalayan region originates from northern slope of the Bandar Punch peak and joins Yamuna at Kalsi before Yamuna enters the plains. The Tons contributes nearly twice the volume of flow of the Yamuna at their confluence. River Yamuna emerges on the plains near Hathnikund in Haryana where the water is taken off by

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the western and eastern Yamuna canals. The river flows further 280 km to Okhla in Delhi from where the Agra canal takes off. River Hindon joins the Yamuna on its left bank, 40 km below Okhla. Finally, passing through Agra, Etawah and Hamirpur, Yamuna meets Ganga at Allahabad. The total length of Yamuna from its origin to Allahabad is 1376 km. Small tributaries like the Karan, Sagar and the Rind join it on the left bank but Rivers Chambal, Sind, Betwa and Ken flowing from the Vindhyas are large rivers joining it on its right bank. The Chambal rises in Vindhyan ranges and flows for 965 km before joining Yamuna. Three dams viz. Gandhi Sagar, Rana Pratap Sagar and Jawahar Sagar have been constructed on river Chambal. The Sipra, Choti, Kalisindh, Sivana, Ansar, Retam, Banas, Seep, Kund, Parvati, Kunwari and Pahuj are some of its tributaries. R. Sind originates in Vidisha district, is 415 km long and meets Yamuna downstream of the confluence of R. Chambal and R. Yamuna. R. Betwa rises in the Bhopal district and joins Yamuna near Hamirpur after flowing 590 km. R. Dhasan is one of its important tributaries. Another important tributary, the R. Ken rises in the Kaimur hills of Satna district of Madya Pradesh. It traverses 360 km up to its confluence with the Yamuna near Chilla (Banda). The Ramganaga System A number of small streams originating from the Chorkhaldhar and the Khankarkhet ridges of the Dudhatoli range form the upper tributaries of the R. Ramganaga. R. Mandal, largest Siwalik river of eastern Garhwal, meets Ramganga at Loharchaur and a littile downstream, R. Palain meets Ramganga at Buksar. It enters the bhabar area at Kalagarh and further drains the Bijnor district. Rivers Originating in Nepal Ghagra, Gandak, Bagmati, Kamla and Kosi, arising in Nepal, are most important tributaries of river Ganga. R. Ghagra, known as Manchu and Karnali in Nepal, has its source near lake Mansarovar. Ghagra enters India at Katarniaghat. The Girijapuri barrage has been constructed below Katarniaghat and two canals on either side takes off from there. R. Sharda or Chauka, which forms the boundary between India and Nepal, is an important tributary of Ghagra. Other tributaries are R. Rapti and R. Little Gandak. Rapti, which meets Ghagra on the left, rises in Nepal and descends to the plains at the border of India with Nepal. Ghagra flows for 1080 km before joining Ganga a few km downstream of Chapra town in Bihar.

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R. Gandak is known as Kali in Nepal and rises at 7620 m altitude in Tibet near Nepal’s border overlooking the Dhaulagiri peak. The Gandak debouches into the plains at Tribeni in Bihar. At this site Bhainsalotan barrage has been constructed and a canal takes off on either side. R. Gandak flows for another 300 km before joining R. Ganga near Patna. R. Bagmati rises in the Shivalpuri hills of Nepal and enters India in Muzaffarpur district. It joins Kosi in the lower reaches. R. Kamla along with its several tributaries also rises in Nepal. It enters India near Jaynagar in Darbhanga district and joins the Kosi. R. Kosi is formed by the confluence of three rivers, the Sun Kosi, the Arun Kosi, and the Tamur Kosi in Nepal. After the confluence, the river flows through a narrow gorge for 10 km and enters the plains at Chatra. After traversing a further 25 km, it enters India near Hanumannagar. A large barrage has been constructed at Hanumannagar from which two canals take off on either side. After running about 320 km below Chatra, the Kosi joins R. Ganga near Kursela. The Sone Sub-basin River Sone originates at Amarkantak and after passing in cascades over the hill reaches, it receives River Rihand. Other important tributaries of Sone are North Koel, Kanhar and Ghagar. After flowing over 784 km, R. Sone meets Ganga at Koilwar near Patna. A weir was constructed at Dehri-on-Sone with a canal on both sides. Downstream of Sone, several tributaries such as Punpun and Kiul meet R. Ganga on its right bank. Other Tributaries There are a few important tributaries which meets Bhagirathi-Hooghly in the lower reach of R. Ganga. R. Dwarka rises in the Birbhum hills and joins Bhagirathi in Murshidabad district. R. Mayurakshi is an important tributary of Dwarka on which a dam has been built. Another tributary Ajoy (276 km long) rises in the Santhal Pargana hills and meets Bhagirathi near Katwa. R. Damodar is 541 km long and rises in the south-east area of the Palamu district and receives an important tributary, the Barakar. Damodar meets Hooghly near Fulta point. Four dams were constructed on Damodar and a barrage at Durgapur from which a canal takes off. River Rupnarayan rises in the Talabi hills and after traversing 254 km, joins Hooghly near Nurpur, downstream of the confluence of Damodar. R. Haldi meets Hooghly further downstream.

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FISH AND FISHERIES Fish Diversity River Ganga harbours 265 fish species (Talwar and Jhingran 1991) of which 181 species are recorded from the freshwater reaches (Payne et al. 2004). Other species include estuarine species or those confined to one country of the Basin (Talwar 1991, Rahwan 1989). The number of species however varies between reaches. The 30 km stretch in and around Patna has 106 species (Hassan 1999). River Alaknanda has the lowest number of species (41 species) among all reaches that is still appreciable for a single cold, upland river. The fish community is characterized by a few specialized cyprinids, especially species of Schizothorax, Tor and small Garra along with some of the mountain loaches, Noemacheilus sp. and the highly specialized sisorid torrent cat fishes, Glyptothorax sp. The fish community of the upper Ganga is very similar to that of Alaknanda, although a few lowland species like Mastacembelus and Channa begin to appear. Cyprinids, particularly major carps and catfishes dominate the lowland sites from Allahabad to Bhagalpur. In this segment, migratory species like major carps in the main channel can be distinguished from the small floodplain resident species with accessory respiratory organs and prolific reproduction. Downstream of Patna, some species from the estuarine sector such as the scieanid, Scieana coiter, the mullets, Rhinomugil corsula and Scomugil cascasia start appearing. Particularly significant is the anadromous Tenualosa ilisha or 'hilsa' (Payne et al. 2004). Upland Stretch of River Ganga The upper Ganga basin can be broadly divided into three components: a) Yamuna and its subsystem draining North-Western Himalaya, b) Ganga draining WestCentral Himalaya-Garhwal region, and c) River Ganga draining Central Himalaya-Kumaon region. Yamuna Sub-System Yamuna and its tributaries, Tons, Gir, Asan, sustain large subsistance fishery (Sehgal 1992). The coldwater fishery mainly-Mahseer, Indian trouts, Barilius sp. and Bagarius sp.are reported mainly from the upper reaches up to Tajewala barrage. Mahseer fishery used to thrive in this stretch along with minor carps and Bagarius. Large Tor putitora (weiging up to 25 kg) has been caught in this stretch (Soni 1998). But the fisheries

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dwindled drastically due to formation of large number of barrages both on main Yamuna and its tributaries. However, mahseer is still prevalent in the system as is shown by the yearly angling competition organised by the Haryana Department of Fisheries at Dadoopur Head Works. Mahseer caught now range between 5 and 7 kg. Currently, commercial fishery of low magnitude exists in Yamuna between Dakpathar and Paonta Sahib, composed mainly of Schizothorax. richardsonii, G. gotyla and Tor putitora. Garhwal Himalaya Studies since Menon (1962) described the distribution of fishes in Himalaya, have reported 66 species belonging to 25 genera from various streams of the Garhwal region (Singh et al. 1991). These include Schizothoracids (9 species), Noemacheilus (9 species), Glyptothorax (7 species), Puntius (6 species), Barilius (6 species), and three species each of Tor, Labeo, Gara and Botia. Based of the distribution of fishes, the area is broadly categorized into five zones: i) the zone between 2400 and 3600 m has no fish reported, ii) between1800 and 2400 m, the zone harbours species of Glyptothorax and Pseudecheneis, iii) between 1200 and 1800 m is snow trout zone, iv) between 600 and1200 m is the mahseer zone, and v) between 300 and 600 m is Crossocheilus zone (Singh et al. 1987). However, Schizothoracid fishes have been reported in Deoditta1 lake at 3307 m above sea level (Verma 1994). Snow-trouts, lesser Bari1ius sp. and mahseer form main food fishery of the region. Schizothoracid fishery is mainly constituted by S. richardsonii and S. sinnuatus which together constitute 85% of total catch in upper stretches of A1aknanda and Bhagirathi (Singh et al. 1991). At foothills of Ganga from Rishikesh downwards mahseer - Tor tor and T. putitora forms the main fishery (Singh et al. 1991), along with Barilius, Puntius, Labeo and Mastacembelus (Nautiyal et al. 1998). Recent survey between Tehri and Hardwar found that main food fishes in the region were S. richardsonii, T. tor, T. putitora, L. pangusia, G. gotyla, C. latius and M. armatus (Sinha et al. 1998). The diversity of fishes in R. Alaknanda and their ecological status are given in Table 3. An accurate assessment of fishery resources in the mountainous stretch of Ganga is not available due to inherent problems with mountainous terrain and also due to prohibition of fishing in large portion of Ganga which falls under Rajaji National Park. The main commercial

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fishery starts from Hardwar downstream (Nautiyal et al. Table 3. Inventory of fishes of R. Alaknanda and their ecological status

Species

Ecological status

Family Cyprinidae 1 Schizothorax richardsonii (Gray) 2 Schizothorax sinuatus (Heckel) 3 Schizothorax cur6ifrons (Heckel) 4 Schizothorax niger (Heckel) 5 Schizothorax intermedius (McClelland) 6 Schizothorax micropogon (Heckel) 7 Schizothoraichthys progastus (McClelland) 8 Schizothoraichthys esocinus (Heckel) 9 Tor tor (Hamilton) 10 Tor putitora (Hamilton) 11 Labeo dero (Hamilton) 12 Labeo dyocheilus (McClelland) 13 Garra prashadi (Hora) 14 Garra lamta (Hamilton) 15 Garra gotyla gotyla (Gray) 16 Crossocheilus latius (Hamilton) 17 Barilius bola (Hamilton) 18 Barilius bendelisis (Hamilton) 19 Barilius barna (Hamilton) 20 Barilius bagra (Hamilton) 21 Barilius barila (Hamilton) 22 Danio danio (Hamilton)

Abundant Lower Risk Lower Risk Lower Risk Lower Risk Lower Risk Vulnerable Vulnerable Endangered Endangered Vulnerable Vulnerable Lower Risk Lower Risk Abundant Lower Risk Not Evaluated Abundant Abundant Abundant Abundant Vulnerable

Family Cobitidae 23 Lepidocephalichthys guntea (Hamilton) 24 Botia dario (Hamilton) 25 Botia geto (Hamilton) 26 Noemacheilus montanus (McClelland) 27. Noemacheilus rupicola (McClelland) 28 Noemacheilus bevani (Gunther) 29 Noemacheilus savona (Hamilton) 30 Noemacheilus multifasciatus (Day) 31 Noemacheilus zonatus (McClelland)

Lower Risk Lower Risk Lower Risk Abundant Abundant Abundant Abundant Abundant Abundant

Family Amblycepidae 32 Amblyceps mangois (Hamilton)

Vulnerable

Family Sisoridae 33 Glyptothorax catia (Hamilton) 34 Glyptothorax pectinopterus (McClelland) 35 Glyptothorax madraspatanum (Day) 36 Glyptothorax brevipinnis (Hora) 37 Glyptothorax conirostris (Steindachner) 38 Pseudecheneis sulcatus (McClelland)

Abundant Abundant Lower Risk Lower Risk Lower Risk Vulnerable

Family Schilbeidae 39 Clupisoma garua (Hamilton)

Data Deficient

165

1998, Sinha et al. 1998). Total catch estimated in Alaknanda and Bhagirathi river system amounts to 1-25 kg per day involving 10-15 fishermen. The catch is high during winter (ranging 5-50 kg perday in Saung and 5-35 kg per day in Nayar (Nautiyal et al. 1998). But mahseer fishery is common during monsoon in these two tributatries, and range ranging 19 to 55 cm in size (Nautiyal et al. 1998). Kumaon Himalaya The Kumaon region of Central Himalaya is drained by three tributaries of Ganga - Kali, Ramganga, Sarju, and a portion of A1aknanda. These rivers harbour coldwater fishes all along their course. Fisheries are composed mainly Schizothoracids in the upper reaches and mahseer in lower reaches (Raina 1997). Schizothorax species constituted 21.5, 24.9, 4.8 and 16.7%, respectively in rivers Sarju, Kosi, Ramganga and Bhadargarh whereas Tor species accounted for 10.7, 14.9,24.0 and 10.0%, respectively (Pathani 1994). Mahseer has been reported to have declined from 40.5% to 15.2% during 1970s and 1980ss in the Kumaon waters (Pathani 1994). In addition, there are several lakes such as Naukuchiatal (37 ha) and Nainital (45 ha). Joshi (1999) recorded from these lakes 43 coldwater fish species of which 34 are native and 9 are exotic; and are mainly represented by Noemacheilus (5 species), Puntius (5 species), Barilius (3 species) and 2 species each of Tor, Labeo and Schizothrorax (S. kumaonensis and S. richardsonii). The production from lakes is estimated to be 9.32 kg ha-1 yr-1 (Bhimtal); 13.62 kg ha-1 yr-1 (Sattal) and 0.74 kg ha-1 yr-1 (Nainital; Pathani 1994). It has been observed by many workers that potamon zone of these rivers at the foothills of Himalaya harbours rich eurythermal coldwater fishery of commercial importance (Sehgal 1992, Nautiyal et al. 1998 and Joshi 1999). But so far there is very little information on magnitude and composition of this fishery in such resources. Fish Population Structure in Plains River Yamuna The potamon zone of river Yamuna starts from Hathnikund to Yamunangar, which drains the foothills of Himalaya between Uttar Pradesh and Haryana. At Hathnikund, the main fishery within Yamuna was mahseer and minor carps: T. putitora 11.53%, L. gonius 47%, L. dyocheilus 10%, L. bata 4.6% and W attu

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7.69%. The catch is disposed off at Faizabad on eastern side of the river. Experimental fishing in the area ranged 240 to 400 g man-hr-1 depending upon the season, with a maximum in the late winter. Average size of T. putiora ranged between 0.3 to 3.0 kg (325-650 mm length). At Dadoopur, where R. Giri is dammed, the commercial fishery mostly comprised of Tor putitora and T. tor 27.76%, L. calbasu 27.76%, Dero 11 %, L. bata 11 %, B. bagarius 11.11 %, M. armatus 5.55%, and Chela sp. 3.0%.. During 1997-99, average catch at the Yamunanagar landing centre was 41.05 kg day-1 and the fishery mainly comprised of L. bata 11.7%, L. gonius 4.9 %, L. calbasu 5.0%, T. putitora 9.0% and C. carpio 6.5 %, besides L. dyocheilus and L. dero. Catfishes (18.46%) and grasscarp, C. idella, were also reported (Moza and Mishra 2000). Mahseer wass more than the 3 species of Indian major carps. However, this species has declined because of habitat destruction during the construction of Hathnikund barrage (Moza and Mishra 1994). Ganga River System The potamon zone of Ganga starts from Rishikesh and extends upto Bhogpur, but fishing between Rishikesh and Hardwar is banned. The commercial fishing within the zone starts 4-5 km below Hardwar from Kankhal to Bhogpur with Ajitpur as fish landing centre. Annually, 2 days fishing is allowed by Forest the Department during last week of February within Chilla and Ganga Lehri area of the river (Prohibited zone). The area is A good source of coldwater fishery. Yearly assessments were made during 1993-1995 at Raiwala landing centre (between Rishikesh and Hardwar) and during 1998-2000 at Ajitpur landing centre (below Hardwar). At Raiwala, the catch was mainly composed of mahseer fishery (66%), Schizo thorax fishery (6%), Eel (15%), L. calbasu (l %) and others 12%. At Ajitpur the composition was mahseer 25%, Schizothorax 3%, Eel 10%, minor carps 50%, (mostly Labeo calbasu), catfishes, mainly W. attu 5% and others 7%. Eel was present mostly in monsoon (Anon. 2000). Fishing has been strictly prohibited from 1996 at Raiwala. The average catch in potamon zone of Ganga was 90 kg day-1 with the maximum during premonsoon (up to 1531 kg day-1 ) compared to only 9-98 kg day-1 during the postmonsoon, involving 30-40 fishers. Experimental fishing from 1997 to 2000 showed that both fish composition as well as fishing effort are on decline in this zone. The composition in post-spawning period in 1997 was T. tor 0-36%, T. putitora 10-30%, L dyocheilus 0-36%, L. calbasu 0-50%, whereas during

Int. J. Ecol. Environ. Sci.

2000, mahseer formed only 7.7%, L. bata, 30-76%, L. dyocheilus 30-76%, W. attu 15-36% and others 15-34%. Although mahseer declined in proportion but its average size range did not show any variation. The catch per unit effort declined from to 1.0 kg to 0.575 kg man-hr'. Experimental fishing during monsoon returned mahseer 41.6%, C. catla 25%, L. rohita 16.76%, and W. attu 16%. The catch per unit effort was very low (0.17 kg man-hr-1 . Rao (2001) accounted 83 fish species in the upper Ganga (Rishikesh to Kanpur) and suggested developing protected areas for long term conservation. Payne et al. (2004) described 30 and 56 fish speciesfrom Allahabad and Patna stretch respectively, and established significant correlation between catches and river discharge. Recently, Sarkar et al. (2007) recorded 46 species representing 19 families and 33 genera, from Samaspur Bird Sanctuary, Uttar Pradesh. In Ganga, commercial fishery starts from Anupshahar (Jhingran and Ghosh 1978) and the middle stretches of Ganga are considered to be rich source of fishery. The fish landings at major commercial fish landing centres in different stretches of river Ganga (Table 4) show a decline in fisheries of which the worst sufferers were major carps and hilsa. During 1961-68, the fishery in Kanpur to Bhagalpur stretch has a high annual yield rate of 1169 kg km-1 (Table 5) that varied from 1803.3 kg km-1 at Patna to 781.5 kg km-1 at Bhagalpur. Major carps dominated from Kanpur to Allahabad (Jhingran and Ghosh 1978). After 1972, Ganga river fishery started declining with sharp changes in stock structure. At Allahabad, the yield decreased from 935.2 kg km-1 (total 97.73 Mg) of 1960s to 389.6 kg km-1 (total 12.57 Mg) (Table 6) along with a drastic decline in the catch of major carps and large sized catfishes (A. aor, A. seenghala, W. attu). However, the catch of smaller species remained at the earlier level with only slight changes in catch composition. During 1991-2000, the contribution of L. calbasu declined sharply and major carps’ share slipped to merely 28.9 kg km-1 . During 2001-08, the fisheries improved in general, mainly due to invasion of exotic species, C. carpio and O. niloticus, which are constantly increasing over the years. At Buxar, hilsa was the main fishery which declined sharply from 1972 to 1980 with the commissioning of Farraka barrage. During 1960s the fish yield at Buxar was 1112.9 kg km-1 , of which 744 kg km-1 was contributed by hilsa. After 1972 the hilsa fishery suffered a serious setback and came down to only 22.4

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Table 4. Fish landings (Mg) at different centres on Ganga

Year

C. mrigala C. catla

L. rohita L. calbasu Major carps A. aor

A. seenghala W. attu

CatFish T. ilisha Exotic Others

Total

Allahabad 19 61-68 1972-80 1981-90 1991-00 20 01-08

48.75 45.51 56.95 40.99 47.47

215.14 101.49 116.62 63.10 88.99

33.48 2.43 1.01

11.13 6.23 13.87

50.08 15.58 24.11

22.43 11.67

14.08 0.08

48.82 28.18

108.68 47.04

31.23 24.67 26.75

4.27 0.68 0.93

59.02 48.45 52.52

113.18 85.56 86.17

52.38 8.50 5.96 1.08 3.68

15.33 3.32 3.26 1.67 3.67

16.78 2.59 2.76 1.19 3.37

13.24 16.68 23.84 2.71 1.84

97.73 31.09 35.82 6.65 12.57

20.10 11.85 10.40 7.58 4.86

14.59 7.22 9.18 5.37 2.92

11.62 3.59 3.29 1.48 1.24

46.31 22.67 22.86 14.43 9.02

22.35 2.22 0.99 1.04 0.22

0.57 0.40 0.54

0.70 1.02 0.46

0.71 1.18 0.67

0.12 0.30 1.59

2.10 2.89 3.25

2.02 2.15 2.38

0.79 1.36 1.55

0.56 0.54 2.06

3.37 4.05 5.98

10.02 0.83

4.28 2.98

8.22 2.20

0.83 1.10

23.35 7.10

10.61 4.80

** 4.55

11.82 2.32

5.38 2.70 1.35

8.19 5.87 2.83

4.41 2.55 1.45

0.68 0.65 0.36

18.66 11.76 5.98

4.95 4.44 6.48

5.95 4.36 3.65

20.33 15.87 16.61

19.72

Buxar 1963-71 1972-80 1981-86

Patna 1961-66 1986-93

Bhagalpur 1961-70 1972-80 1981-88

Table 5. Yield rate (kg km-1 ) in different stretches of river Ganga, 1961-68

Centre

Kanpur Allahabad Varanasi Buxar Ballia Patna Bhagalpur

Major carps Large catfishes 365.0 430.0 46.2 37.8 57.1 331.7 149.2

317.5 203.9 327.7 68.9 124.3 370.0 163.1

Hilsa

0.0 93.9 443.1 917.8 485.7 193.3 31.5

Others

Total

272.5 207.4 684.6 304.4 210.0 908.3 437.7

955.0 935.2 1501.5 1328.9 877.1 1803.3 781.5

Table 6. Fish yield rate (kg km-1 ) in different periods at Allahabad

Period

1972-80 1981-90 1991-00 2001-08

Major carps 135.17 155.73 28.91 54.65

Large catfishes 98.55 99.40 62.74 39.20

Hilsa Exotics Others Total

9.66 4.31 4.51 0.96

85.72

197.86 247.59 178.2 206.38

441.25 507.03 274.36 389.61

kg km-1 in 1981-86. Somehow, the overall fisheries improved during 1981-86 due to the contribution of other species. The yield of major carps increased from 46.7 to 72.3 kg km-1 and large catfishes almost doubled to 74.9 kg km-1 . At Patna centre also, the fish yield declined from 1811.3 kg km-1 to only 783.9 kg km-1 during 1986-93. Smaller species also suffered badly in this stretch; their yield slipped from 813.7 to 469.7 kg km-1 . Major carps landings drastically declined in 198693 to less than half of that in 1960s. The contribution of hilsa was reduced to negligible (1.4 kg km-1 ). At Bhagalpur, the decline was not as severe as at other centers. The yield declined to 662.9 kg km-1 in 1981-88 from 870.6 kg km-1 in 1961-70. Large catfishes and smaller species declined a little but major carps and hilsa fishery suffered badly. The contribution of major carps came down from 143.5 to 46.0 kg km-1 and hilsa contributed only 7.1 kg km-1 . Gupta and Tyagi (1991) have observed that the fishery is harvested at a level higher than the optimum fishing level, and that efforts should be made to reduce the fishing pressure to obtain a sustainable fishery from the system. With the construction of Farakka barrage, the fishery at Lalgola centre (about 45 km below Farakka) also had a major change in stock structure: the contribution of hilsa declined from 92% to merely 16.8% and the niche was replaced by other species (Table 7).

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Table 7. Catch composition (%) at Lalgola during preand post-Farakka periods

Group

1963-76

Major carps Large catfishes Hilsa Others Total (Mg)

0.33 0.12 92.02 7.53 121.43

1980-90

1991-00

4.47 9.34 29.68 56.51 57.31

9.76 13.58 16.80 59.86 106.35

On the contrary, manifold increase in fish yield has been observed in the estuarine zone during post-Farakka barrage period. The average annual prawn and fish yield from the estuary increased from 9,481.5 Mg during pre-Farakka barrage period (1966-67 to 1974-75) to 33,341 Mg during post-barrage period (1984-85 1994-95) and further to 42,703.2 Mg during 1995-97. Increased flow of freshwater in the estuary has improved the habitat of hilsa for its migration, breeding and growth, resulting in increased landing from 1,457.1 Mg in 1975 to 5,045.8 Mg in 1995-97. species now spawns in the entire freshwater zone of the estuary. Certain freshwater fishes and prawn species viz., Eutropiichthys vacha, Clupisoma garma, Rita rit.· Wallago attu, Aorichthys seenghala, A. aor, C. catla, Labeo bata etc. have made their appearance in the entire upper estuarine zone up to Uluberia. The estuarine fisheries and hilsa are discussed in greater detail in the next section. Hooghly River and its Estuarine Fishery R. Hooghly is a coastal plain estuary, flowing for about 295 km through the districts of Nadia, Hooghly, North and South 24 Parganas, Howrah and East Midnapore in West Bengal.. It is one of the most important estuarine systems of India because of it being a part of a large Himalayan river, its heavy monsoonal drainage from a vast basin, very long tidal zone, its association with the large mangrove forest, the Sundarbans.and its being the navigable waterway for the ports of Calcutta and Haldia. The main estuary is classified as a positive estuary in the mixohaline range (Pantulu 1967) where mixing of the freshwater and regular tidal influxes have created a steady gradient from marine to freshwater conditions. This estuary is further characterized by the heavy load of silt and suspended matter which it carries throughout the year.

Int. J. Ecol. Environ. Sci.

Salinity is the most significant factor, in relation to the fishery resource of Hooghly estuarine system (Gopal Krishnan 1968, Jhingran and Gopal Krishnan 1973). The Hooghly estuary is classified into three distinct zones based on salinity: freshwater zone (Nabadwip to Uluberia), true estuarine or gradient zone (Diamond Harbour to Kakdwip) and marine zone (Kakdwip to Freserganj). The freshwater zone (zone I) had low salinity (mean 0.024-0.033 g L-1 .) during 1982-93 which was slightly higher (0.05-0.063g L-1 ) during 1994-2004. Salinity was higher in gradient zone (0.45-8.85 g L-1 ) during 1982-93and increased to 1.09-9.5 g L-1 during 1994-2004. The marine zone (zone III) had appreciably high salinity (mean 8.8 to 18.6 g L-1 ) during 1982-93, which increased to 9.5-25.1 g L-1 during 1994-2004. During pre-Farakka period (1960-61) maximum salinity of Hooghly estuary ranged 0.2-32.8 g L-1 , the minimum being at Barrackpore and maximum at Kakdwip. After construction of Farraka barrage, salinity dropped significantly in freshwater zone and gradient zone obviously due to dilution by freshwater from river Ganga. Salinity of Hooghly reached a minimum during 1985, after which there was a slight increase all over the estuary (Sinha et al. 1996) . Vertically, it is a well mixed estuary (with slight stratification in monsoon) because of the uneven substratum, violent tides, bores, morphology of the mouth region and silting pattern (Pantulu and Bhimachar 1964). After commissioning of Farakka Barrage salt front has been pushed seaward and rarely penetrates beyond Diamond Harbour, 80 km from the river mouth. Like other estuaries,Hooghly also supports a rich biodiversity. Jhingran (1991) reported 172 species of fish from the estuarine and coastal areas of West Bengal. A recent survey (April 2005- July 2007) of Hooghly estuary and Sundarbans mangrove area conducted by the Central Inland Fisheries Research Institute (CIFRI) recorded 135 species of bony fishes belonging to 20 orders and 61 families from freshwater, transitional and high saline zones of the Hooghly estuary. Five species of shark and skates/ rays belonging to two Orders and four families were also recorded, besides 13 prawn and 8 crab species from different salinity zones. The commissioning of Farakka barrage. to augment freshwater discharge into Hooghly estuary, has resulted in major change in the ecology of Hooghly-Matlah estuary. Large scale change in salinity structure has resulted in extension of freshwater stretch towards downstream (Sinha et al. 1996). The earlier recognised gradient-transit zone has shifted from Uluberia to

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Nurpur by about 40 km downstream in the estuary. Significant structural changes in the fishery resources as well as fishing patterns were observed in the upper zones and the lower estuary. Total average yield from the estuary increased from 9,481.5 million Mg between 1966-67 and 1974-75 to 28,805.7 million Mg between 1984-85 and 1993-94. Since the commissioning of the Farakka Barrage in early 1970s, many of the species like Liza (Mugil) parsia, Scatophagus argus, Odontamblyopus rubicundus, Osteogeneiosus militaris, Hemiramphus gaimardi, Mystus gulio, Periopthalmus sp., etc. have shifted downstream. Polynemus paradiseus is encountered only occasionally. However, some freshwater species, e.g., Sicamugil cascasia a small mullet, have invaded this zone migrating from the upper stretches. This purely freshwater species has not been reported from this zone of Hooghly earlier (Ghosh 2007). More importantly, the occurrence of different sizes of Sicamugil cascasia (36 mm--46 mm) also indicates a purely freshwater condition in this stretch. The entire zone between Nawabgunj and Diamond Harbour virtually became freshwater zone. Salinity increases slightly during summer months at Diamond Harbour but here also some freshwater species are encountered particularly during monsoon and post-monsoon months. Recent studies at the CIFRI indicate such changes also in the lowest part of the Hooghly estuary. Bregmaceros mcclellandi, the spotted codlet, a small fish belonging to the family Bregmacerotidae (order Gadiformes), is rare on the eastern coast of India though it forms a sizeable fishery on the west coast (Talwar and Kacker 1984). Recent investigations revealed the presence of the species in Fresergunj-Bakkhali and around Sagar island, Jharkhali (Hnerobhanga estuary, Sundarbans), and Hingalgunj (Ichhamati estuary, Sundarbans). Mugil cephalus, Liza tade, etc. have become rare and Tenualosa toli is no more encountered. Of the thread-fin fishes, the ‘Mango fish’ Polynemus paradiseus, has declined in the catches from the lowest part of the Hooghly estuary (Table 8). The so-called Indian Salmon, Eleutheronema tetradactylum, is an estuarine species, the seeds of which are found in plenty in the high salinity zone of the Hooghly and Matlah estuaries and in the estuarine complex of the Sundarbans (Talwar et al. 1992). Polydactylus indicus, another threadfin, constitutes only a small part of the total landing from Fresergunj/Bokhali area or Sagar island. The giant perch, Lates calcarifer has been recorded from marine zone to freshwater zone (up to Barrackpore–Bichalighat stretch). The mullet, Rhino-

mugil corsula and the flat fish, Cynoglossus cynoglossus (Pleuronectidae) also occurs from marine to freshwater zone of the estuary.

Table 8. Species-wise fish landings (Mg yr-1 ) from Hooghly Estuary

Species

Pre-Farakka Post-Farakka 1985-1988 2004-2005 1967-75* 1976-78

Tenualosa ilisha 1551.0 Setipinna sp. 770.1 Trichiurus sp. 497.9 Harpodon nehereus 2184.9 Pama pama 232.0 Tachysurus jella 180.4 Polynemus paradiseus 59.6 Coilia sp. 113.1 Ilisha elongata 181.9 Sciaena biauritus 215.2 Liza parsia 50.2 Lates calcarifer 25.1 Prawns 1388.5 Others 2566.2 Freshwater fishes Total 10016.1

1939.8 468.1 1544.7 3978.7 5486.0 152.7 107.9 154.7 952.2 315.5 51.4 28.4 1506.1 3413.6 20099.8

1721.8 2377.3 1802.7 4240.9 2844.8 613.6 192.5 847.8 478.3 435.3 26.8 6.6 2116.7 8116.5 70.8 25892.2

8427.1 5758.8 4227.1 7560.0 8349.0 2949.2 281.2 2270.3 901.0 26.5 220.3 104.3 6232.5 18065.6 482.9 65855.8

*Excluding 1971-72

The fisheries of the Hooghly estuary have welldefined annual cycle of qualitative and quantitative variability. During the monsoon season, fish yield mainly comprises of hilsa, winter catches include harpodon, sciaenids, threadfins, ribbon fishes, cat fishes, perches etc., and during summer a thin population of miscellaneous species contributes to the fish harvest. A large fish and prawn diversity is observed in the freshwater zone, particularly in the lower stretch from Uluberia to Diamond Harbour. Euryhaline species are also encountered in the region. The fish and prawn fauna between Nabadwip and Calcutta include: Tenualosa ilisha, Aorichthys seenghala, Eutropiichthys vacha, Clupisoma garua, Setipina phasa, Ailia coila, Puntius ticto, Mastacembelus armatus, Bagarius bagarius, Pangasius pangasius, Xenentodon cancila, Amphipnous cuchia, Mystus cavasius, Ompak pabo, M.gulio, Notopterus notopterus, N.chitala, Wallago attu, Labeo rohita, L.calbasu, Catla catla, Cirrhinus mrigala, L.bata and

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Chela sp. Among prawns, Macrobrachium rosen-bergii, M. malcomsonii, M. rude, M. villosimanus, M. lamarrei, M. mirabiles, M. birminicum, M. scabriculum and M. dayanum occur in this stretch. The featherback (N. notopterus and N. chitala) and carps (L. rohita, L. bata, L. calbasu, C. catla and C. mrigala) are mostly confined to the stretch between Nabadwip and Tribeni and their abundance is poor in the total catch. The important fishes between Uluberia and Diamond Harbour are Pama pama, S. phasa, T. ilisha, Polynemus paradiseus, Silaginopsis panijus and Rhinomugil corsuls. Among prawns Macrobrachium rosenbergii, M. mirabile and Metapenaeus brevicornis are the most dominant species. Freshwater species such as E.vacha and C. garua are available upto Uluberia. Dominant species in the gradient as well as marine zone of Hooghly including other estuaries of Sunderbans are Harpodon nehereus, Trichiurus species, Tenualosa ilisha, Setipinna species (mostly S. taty). P. pama and prawns (Parapenaeopsis sculpilis, P.stylifera, Metapenaeus brevicornis, M.monoceros, Penaeus monodon, P.indicus, P.semisulcatus, Expalaemon stylifera, E. tenuipes and Leptocarpus fluminicola). Next to these other important fish species are P. paradiseus, Eleutheronema tetradactylum, Lates calcarifer, Polydactylus indicus, Coilia spp., Stromateus cinereus, Arius sona, A.sagor, Ilisha elongata, Osteogeniosus militaris, Otolithoides biauritus, S.panijus, Liza parsia, L.tade, Chirocentrus dorab, Raconda russeliana, Plotosus canius, Cynoglossus sp., Anchoviella commersonii, Scatophagus argus, Etroplus suratensis, Therapon jarbua, Synbranchus bengalensis, Strongylura strongylura. Hilsa Fishery Hilsa (Tenualosa ilisha) is the only important anadromous species migrating to the Indian river systems. The species is commercially the most important fishery of the estuary. The hilsa migrates to the freshwater environment of the Ganga river system through the Hooghly estuary. Fishing activity for the species starts from the coastal zone of the Bay of Bengal and continues upstream to the point of their availability. The fishing pressure is maximum in the lower estuarine zone and gradually declines with the lower abundance of the fish stocks. Presently, hilsa fishery occurs up to downstream of the lock gates of the feeder canal at Farakka. The species ascends to freshwater reaches for breeding during the monsoon season. The volume of

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monsoon flows and number of flood pulses have direct bearing on the quantum of its migratory population. The fishery is characterized by wide fluctuations with the precipitation in the catchment areas and volume of freshwater discharge. Freshwater induction through the Feeder canal of Farakka Barrage has caused remarkable alteration in hydrology and salinity gradient of the Hooghly estuary. High dilution of salinity and extension of fresh water tidal zone by replacing the brackishwater regime further downstream cumulatively improved the environment of the upstream stretches of the Hooghly to suitable habitats favorable for the breeding of hilsa spawners. The breeding grounds have shifted to the downstream of Farakka Barrage. The creation of alternative or supportive breeding grounds at the lower reaches of the river system has not only mitigated the problem of physical barrier out of Farakka Barrage but decreased the quantum of juvenile loss during their descending seaward run. Thus, the changes appear to have benefited the recruitment and enhancement of the hilsa fisheries. The annual yields fluctuate greatly between 1087 and 2854 Mg forming 3.6 to 16% of the total catch. The annual average catch of 1754.9 Mg recorded during pre-Farakka period (1961-1975) has increased to 5327.4 Mg for the peeriod 1981-2005. Hilsa catch during 1990-91 peaked at 6655.9 Mg indicating also a ten year cycle of high yields. Generally, 80-90% of hilsa are captured during monsoon months (July to October) mostly by engaging drift gill nets (locally known as ‘Chandi jal’, ‘dholi jal’, ‘kona jal’ etc.). Besides this, gill nets, purse nets (locally known as ‘sanglo jal’) and set-gill nets (locally known as ‘nangar jal’) are also used exclusively for catching hilsa. During monsoonal migration upstream for breeding, large size fishes (3-5 year age group, length 20 to 55 cm) dominate the catch. Migratory Bagnet Fishery The Hooghly has an unique feature of concentrated bagnet fishery in lower mixing or transit zone during winter season. Every winter the fishers operating bagnets migrate to the Sundarban coastal areas and camp for the entire season for about 4-5 months. These fishers join into several groups and establish fishing camps on the sea coasts. These camps along with fish drying yards are locally called ’khuties’. Two major concentration of such khuties are established, one on the Sagar island and the other cluster around Fraserganj, Bakkhali, Kalisthan, Upper and Lower Jamboodwip. The number of khuties

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was limited to a few until early 1960s but has increased from year to year. The fisher population migrating to different centers, the number of bagnets deployed and mechanized and non-mechanised boats put into operation during 1984-85 to 1993-94 also indicated the increasing trend. With increased freshwater discharge and deeper intrusion of estuarine mixing zone into the inshore areas of the Bay of Bengal the area for bagnet fishery has increased. The total catch from winter bagnet fishery increased from average 2579.33 Mg in pre-Farakka periods (1960-75) to an average of 25380.3 Mg after the Farakka Barrage was constructed (1976-2004). Dutta et al. (1975) opined that the increased abundance of fish mainly results from the winter blooms of plankton causing feeding and breeding migration of the fishes and prawns in the estuary. Large amounts of organic matters, detritus and other washed off materials flow and deposited below the mouth of the estuaries fortify the estuarine water leading to production of planktonic bloom. The composition of the bagnet hauls comprise large number of demersal species migrating from neritic and offshore areas of the Bay of Bengal. The webs of food organisms like planktonic bloom, swap of gammarus, isopods and sagitta attract the juvenile fish and prawn and these juveniles are followed by the large carnivorous fishes. In a nutshell the bagnet catches mostly composed of carnivorous species of fishes. Fishes, smaller in size and deformed of shape in the bagnet hauls are preferred for drying while the bigger fishes are marketed fresh with higher values. Some of the marine and typically neritic species. viz.. L. parsia among mullets, E. tetradactylum among poly-nemids, Colia sp. among anchovies, T. toli and I. elongata among clupeids and H. nehereus and Trichiurus sp. among others have shown a sharp declining trend or total absence in the upper estuary. Total landing in Zone I has declined over the years whereas the total catch in Zones II and IV did not change significantly between pre-Farakka to post-Farakka and recent years. Average species composition during the three periods shows that a few freshwater fish species (Rita rita, Wallago attu, Mystus aor, Ailia coilia, Catla catla, Labeo rohita, L. calbasu, L. bata) and freshwater prawn (Macrobrachium rosenbergii) have now started appearing in the catch from the upper estuarine waters where the salinity has almost become zero. Hilsa catches also increased in the upper estuary during 1984-85 to 1993-94. A comparison of data on the total number of

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different gears used during 1982-83 with that on gears during 1956-58 shows that the relatively high catch of hilsa and low catch of P. pangasius, S. panijus and S. phasa are perhaps not due to ecological change only but also due to changes in fishing pattern or effort in recent years ( Mitra et al. 1987). Trawls, seines, purse (or clap) and lift nets, traps and long lines have declined in all zones whereas the gears operated for catching hilsa increased significantly (165% increase in drift gill nets in Zone IV). While bagnets dominated the gears earlier in all zones of the upper estuary, drift gill nets (for hilsa) are equally dominant as bagnets in zones I and II. The catch by other gears, viz., bag, trawl, lift, seine, cast, hooks and line and traps comprise mostly of small sized prawns and other varieties of fish. Thus, changes in the species composition in the upper stretch of Hooghly estuary in recent years is due to ecological changes as well as changes in the fishing pattern and effort. Hence, models based on catch and effort only (Schaeffer 1954) for the assessment of maximum sustainable yield (MSY) cannot be effectively used in case of Hooghly. Fish Spawn Availability in River Ganga Fish seed in Ganga river system is collected in the form of eggs, spawn (hatchlings up to 8 mm long), fry (seed, >8 to 40 mm long) and fingerlings (fish seed, >40 to 100 mm in length).These definitions were adopted by the fish seed committee in 1966 for the sake of uniformity of usage throughout India. The collection of spawn on commercial scale is prevalent in Bihar, West Bengal and Uttar Pradesh. About 75 spawn collection centres on the Ganga, Yamuna, Betwa, Gomti, Ramganga, Rapti, Ghagra and a few other smaller streams are registered with the Uttar Pradesh Government. In the Ganga river system, major carp spawn are available from May to September. First appearance of spawn in India occurs in River Kosi due to flood caused by snowmelt in mid-May or early June. Rivers Ganga, Gomti, Yamuna experience spawning only after flooding by heavy rains. Kursela centre situated just below the confluence of Kosi with Ganga, first receives spawn from Kosi and then that of Ganga. Spawn prospecting studies were initiated by the CIFRI and intensified in 1964 to help establish many productive centres in the Ganga river system. Later, the All India Coordinated Research Project initiated in 1971, established excellent sources of quality fish seed at Sapori (Tank) on the Banas, Anwara (Agra), Dhumenpur (Etawah), Kishanpur

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(Fatehpur), Mahewa Jamunapur (Allahabad) on the Yamuna and Salempur (Lucknow) on the Gomti. In the lower stretch of Ganga and its tributaries in Bihar and West Bengal, spawn is collected by private fishermen on a very large scale and there exists a private trade. (Dwivedi 1999)

Int. J. Ecol. Environ. Sci.

R. Cauvery (1830-1839). Similarly on rivers Godavari, Mahanadi and Krishna also, hilsa migration has been restricted after construction of anicuts to the portion of the rivers below them, with considerable reduction in stock (Chacko 1952). India does not have many catadromous species. The one noteworthy catadromous species is Indian mottled eel, Anguilla bengalensis living in freshwaters and going to the sea to spawn.

Migratory Fish Species Except a few, most of the Indian migratory fishes are potamodromous. Among freshwater fishes, the big catfish, Pangasius pangasius travels longest distance upstream for reproduction. Fishes living in hill streams exhibit both up and downstream movement periodically in response to rising water levels or temperatures to access food or to new habitats or spawning areas or for the post-spawning movement (Table 9). Tenualosa ilisha is the most popular anadromous species which used to ascend longest distance in the rivers of both eastern and western India. Hilsa ascends for breeding from shoals in the sea into all the major Indian rivers such as Ganga, Brahmaputra, Mahanadi, Godavari, Krishna, Cauvery and Narmada. For Hilsa, the post-monsoon and late winter run is the major run returning to the estuary for growth and survival in semi-saline environment. This follows the early monsoon or late summer upstream migration up to 1300 km (Allahabad on the Ganges, Mettur on Cauvery) above the estuary. (Ghosh 1965, Sreenivasan 1976). This run of hilsa has been affected by Farakka barrage (operational from 1975) on R. Ganga and Mettur dam (constructed 1934) and three anicuts on

SOCIO-ECONOMIC STATUS AND. LIVELIHOODS OF FISHERS The social framework and characteristics of fishers operating in Ganga river provide an insight into their status. The social aspects of fishers are rarely studied (CIFRI 2006, Katiha et al. 1998, Katiha and Sinha 2000). The study by CIFRI (2006) covered about 960 km stretch from Hardoi in Uttar Pradesh to Bhagalpur in Bihar. Following is a summary of data from 162 villages covering 2029 families. Demography The family size for the fisher community changed over the years due to conversion of joint families in the yester years to nuclear families. The overall family size for the river Ganga in the studied stretch was estimated at 4.52. The age distribution of the fisher community showed comparatively higher proportion of minors (55%) than

Table 9. Upstream (U) and downstream (D) migration time and spawning time of major migratory fishes

Species J Tor putitora (Golden mahaseer) Tor tor (Deep bodied mahseer) Acrossocheilus hexagonolepis (Copper mahseer) Schizothorax richardsonii (Snow trout) Schizothorax progastrus Tenualosa ilisha Pangasius pangasius Anguilla bengalensis

Migration direction F M A M J

U U

U U

Spawning time J

A

S

O

N

D

U

U U

U U

U U

U U

D D

D D

D D

August-September May-August

U U U

U

U

U

U

D

D

D

U D

U U D

U U

May-June; August – September March-May March-May July-August June-August June-July

adults (45%). The sex ratio across the age groups varied from 656 to 1053 females per 1000 males in the age

groups 15-29 and