by
K.L. Sehgal
NRC on Coldwater Fisheries (ICAR)
Haldwani 263 139, Distt. Nainital (U.P.), India
102 species of fish are at present listed for the Western Ghats water bodies, situated between 750 and 2000 m altitude. The Western Ghats ranges in western India run for about 1600 km and have an average altitude of 1200 m (max. 2339 m). These important mountain ranges attract precipitation, which is then drained east and west. The three major rivers draining
west are Godavari, Krishna and Cauvery, the last river being famous for its sport and recreational fishing for mahseer (Tor khudree). The fish stocks have been under an intensive fishing pressure from subsistence and sport/recreational fishermen, and this has led to their decline. In certain sections of the Cauvery, under the management of fishing clubs and associations, the stocks are now successfully managed to support the ever increasing numbers of recreational fishermen. Such sections are regularly stocked, and fishing regulations are strictly enforced. The upper streams of the Western Ghats in Karnataka, Tamil Nadu and Kerala, support stocks of rainbow trout. Subsistence fishery targets indigenous fish species, some of which are sold on local markets. Some of the small natural lakes, situated at altitudes from 1340 m to 2500 m, have rainbow trout and common carp, both introduced. In the past the highest yield of 141-179 kg ha-1 was recorded from Lake Ooty (2500 m), but at present this lake is heavily silted and polluted. Aquaculture in uplands is confined primarily to state owned fish farms, which produce rainbow trout and common carp to enhance stocks for recreational fishery, with part of the seed also used for aquaculture fish production. A privately owned hatchery at Lonavla is the major supplier of mahseer fingerlings for stocking angling water bodies.
The triangular configuration of peninsular India is determined in part by the presence of the Eastern and Western Ghats. The Eastern Ghats end near the city of Chennai (Madras), continuing further south as submerged ridges. The Western Ghats are the uplifted western border of the peninsula. The other uplands in peninsular India are the Aravali Range, the Vindhya Mountains and the Satpura Mountains. The Western Ghats are the most important of these mountain ranges from a coldwater fisheries point of view. This paper gives a brief account of the geographical features, ecology, fisheries and aquaculture of the Western Ghats (Fig. 1).
The term ghats expresses the terraced appearance of the mountains and the steps of the terrace indicate successive lava flows. The total length of the Western Ghats is about 1600 km and they provide a great variety of topographic conditions (Krishna, 1968). The Western Ghats (Sahyadri in Sanskrit) commence in Khandesh just south of the Tapti valley. They follow the coast of the Arabian Sea at a distance of 50-60 km from the shoreline. Their average elevation is 1200 m above sea level (Pichamuthu and Radhakrishna, 1968). When viewed from the west coast, the ghats give an impression of rising almost perpendicularly from the coastal plain. The ghats landscape is composed of steep-sided valleys, narrow gorges and waterfalls. Their steep seaward slopes are deeply dissected by rivers and streams and have numerous canyon-like valleys. The landward side slopes, however, are gentle, with wide valleys. The formation of the ghats more or less coincides with the time of the uplift of the Himalayas. As a consequence of the uplift of the Western Ghats all the important rivers of the Deccan Plateau, excepting the Narmada and the Tapti, flow eastwards into the Bay of Bengal though they have their sources on the crest of the Western Ghats, which is only 50-80 km distant from the Arabian Sea coast.
Important peaks in the northern 650 km of Western Ghats are Harischchandargarh (1424 m), Mahabaleshwar (1438 m), Kalsubai (1646 m) and Salher (1567 m), all comprising uplands of Maharashtra. The subsequent 650 km length south of 16oN latitude runs close to the coast until the ranges join the Nilgiri Mountains near Budalur. Vavul Mala (2339 m) is the highest peak north of the Nilgiris while the eastern flank of this range merges gradually with the high plateau of Mysore. North of the Nilgiri plateau between Ratnagiri in Maharashtra and Coorg in the State of Karnataka, the rocks are a heterogeneous assemblage of gneisses and metamorphics including green schists and prominent ridges of iron formations. The important peaks are Kudremukh (1894 m) in Kadur and Pushpagiri or Subrahmanya (1714 m) in Coorg. The Coorg belt is a north-western extension of the Nilgiri Mountains of Tamil Nadu. The Nilgiri or Blue Mountains are the meeting point of both the Western and the Eastern Ghats and the two enclose within them the Mysore Plateau. It forms a level plateau of 2600 km2 which is abruptly cut off on all sides. The two highest peaks there are Doda Betta (2637 m) and Makurti (2554 m). The plateau has an undulating surface and streams meander through rounded grassy hills and patches of forests.
South of the Nilgiris is the Palghat Gap, about 25 km in width at an elevation of 300 m. South of this gap both the eastern and western slopes of the ghats are steep and rugged. In Kerala, the range is flanked by picturesque terraces of laterite which shelve gradually down towards the coast. In elevation they vary from 1000-2500 m altitude. Anaimudi (2695 m), the highest peak in the Peninsula, is a nodal point from which three ranges radiate in three directions - the Annamalai in the north, the Palni in the north-east and the Cardamom Hills in the south. The important station of Kodai Kanal is located in the Palni Hills.
The Annamalai constitutes a series of plateaus divided into lower and higher ranges with rolling topography intersected by deep valleys with dense forests of teak, rosewood, ebony, etc. Annamalai, as well as other ranges of Coorg, Kerala and Tamil Nadu, support large coffee plantations while rubber trees are grown in the lower hills of Kerala. The plateaus of the Annamalai are 1800-2000 m with several peaks rising above 2400 m altitude.
The Palnis consist of two well-marked divisions, the more eastern ranging from 900-1200 m in height (Lower Palnis). The western part has a mean elevation of 2000 m and in one place rises to 2506 m.
The Western Ghats continue south forming the border between Tamil Nadu and Kerala but the elevation of the hills falls gradually to about 1200 m a.s.l These mountains receive both south-west and north-east monsoon rains averaging 5000 mm annually which is conducive to the growth of thick forests which form an abundant source of high quality timber. From Quilon in Kerala in the south to Nagercoil in Tamil Nadu, which is about 20 km north of Cape Comorin, the Ghats lose their identity and only a few low hills are seen.
There are three principal drainages, viz., the Godavari, the Krishna and the Cauvery, draining the Western Ghats towards the east and entering the Bay of Bengal. There are also numerous streams which after flowing through hills end in the Arabian Sea. The true coldwater streams, however, lie in the upper reaches of the Cauvery and the Krishna.
The Krishna, which is the second largest of the eastern flowing inland rivers of peninsular India, rises in the Western Ghats at an altitude of 1337 m just north of Mahabaleshwar. It flows for about 1400 km from west to east through the states of Maharashtra, Karnataka and Andhra Pradesh before entering the Bay of Bengal. It has a drainage of 259,000 km2, and two principal tributaries, the Bhima and the Tungabhadra. The Bhima and its tributaries drain 69,114 km2 of the Krishna basin. Its catchment is in the Western Ghats, starting at an elevation of 975 m in the Poona district of Maharashtra. While the river originates in hills, it flows mostly through plains. The Tungabhadra, with a drainage of 69,560 km2, and the Bhima are the major tributaries of the Krishna. The Tungabhadra originates at the confluence of the Tunga and Bhadra rivers and it also receives the River Hagari. Both Tunga and Bhadra rise in the Gangamula peak of the Western Ghats, Karnataka. Most of their catchments lie in hills covered by semi-deciduous forests and bamboo groves. The Tunga passes through deep valleys amidst broken chains of hills for a distance of 172 km before joining the Bhadra. The Bhadra rises from the north-western face of Kudremukh (1880 m). After descending from the Ghats it loses much of its current velocity and becomes a sluggish river.
The first 708 km stretch of the Krishna in the Western Ghats receives a heavy rainfall during June-September. In Bhadra basin the rainfall ranges from 3300 mm in the hills to about 760 mm in the plains.
The Cauvery rises in the Brahmagiri Hills at an elevation of 1341 m. The river course is tortuous, its bed is rocky and the river banks are high and covered with luxurious vegetation. In the rapids of Chunchankattee the river drops by 24 m. It receives three substantial tributaries: the Moyar, the Amravathi and the Bhavani. A number of small streams arising from the central and southern parts of the Western Ghats and draining the Bababudang Hills of Karnataka and the Nilgiris of Tamil Nadu, also eventually join the Cauvery. These streams originate in thickly-wooded mountains. The pockets of slopes with evergreen forests called sholas, are situated usually above 1200 m. They are also called Southern Mountains Wet Temperate Forest. In the Nilgiris sholas are common between 1500 and 2500 m. Shola trees (Syzygium, Elaeocarpus, Ilex, Vaccinium, Rhododendron etc.) below 2000 m rarely exceed 15 m in height. Tea is also grown widely and silver oak is used extensively as shade trees. At Mettur the river has been dammed and below this dam the Bhavani meets the Cauvery.
The Ponnari and the Periyar are the most important drainages of the central and southern parts of the Western Ghats. They flow into the Arabian Sea. They drain the southern face of the Nilgiris and the northern face of the Annamalai Hills, respectively.
The Munnar High Range is drained by streams which ultimately empty into four main rivers, viz., the Amravathi and the Vaigai in the east and the Periyar and the Pambayar in the west. The Chinnar, a tributary of the Amravathi, originates in the high range and joins the Amravathi in the plains. The Suruli, a tributary of the Vaigai, and the Vaigai itself, drain part of the eastern face of the High Range. The Periyar, which drains a greater part of the western face of these hills, ultimately empties into the sea near Cochin. The River Pambayar flows into Lake Vambanad and is not directly connected to the sea. The drainage of Munnar High Range, therefore, can be divided into four main watersheds. They are the Cauvery and the Vaigai watersheds flowing to the east, and the Periyar and Pambayar flowing to the west. In the whole of the High Range there are 38 large tea estates and there is very little forest cover except in the isolated pockets which have been declared a reserved biosphere. These ranges, due to their abrupt rise and closeness to the Arabian Sea, help in checking the southwest monsoon clouds and receive a heavy rainfall of 5000 mm.
The chief source of water is the south-west monsoon. The middle course of the River Cauvery is subjected to fluctuating rains from August to October. Upstream of Mettur, the Cauvery comes under the influence of the south-west monsoon but downstream it receives the north-east monsoon. The highest floods usually occur during July-August, although on rare occasions they have been as late as November.
Many of the rivers flowing eastward have been dammed for hydroelectric power generation. The maximum utilisation of the runoff takes place in Karnataka and Tamil Nadu. This has resulted in the creation of a number of reservoirs. In the Nilgiris almost every stream has been dammed for irrigation reservoirs.
There are very few published accounts available on physico-chemical characteristics and ecology of coldwater streams in the Western Ghats. Some stretches of certain upland streams in the states of Karnataka, Tamil Nadu and Kerala were investigated by Sehgal (1971, 1971a and 1971b). It is known that streams of Bhadra drainage in Karnataka are warmer than the streams which drain uplands of the rivers Cauvery, Vaigai, Periyar and Pambayar in the states of Tamil Nadu and Kerala. During March-April, 1970, the following information was collected for the catchment streams: water temperature 16.5-29.0oC, flow velocity 26-49 cm/sec, pH 7.0-8.2, dissolved oxygen 6.0-8.0 mg l-1, free carbon dioxide 1.2-5.4 g l-1, total alkalinity 78.0-140.0 g l-1, silicates 0.35-1.3 g l-1, chlorides 2-12 g l-1, and nitrates and phosphates in traces. A comparison of physico-chemical parameters of streams of the Western Ghats with those in the Himalayan region (Jhingran and Sehgal, 1978; Sehgal et al., 1984; Sehgal, 1988) indicates that the streams of the Western Ghats have a higher water temperature, free carbon dioxide, total alkalinity and chloride values, but have a lower dissolved oxygen and silicates.
The average numbers of benthic invertebrates in different upland streams ranged between 44-70, with a minimum of two, to a maximum of 191 individuals per m2. In terms of wet weight biomass it varied depending on the dominant group and the size of the organisms recorded in each sample. The average wet weight biomass varied between 3.8 g to 6.8 g m-2, the minimum being 0.75 g and the maximum 10.6 g. Insects contributed 80-87.5% to the total of benthic invertebrates. The other organisms were mainly planarians (Polycelis) and crabs. Benthic vertebrates were dominated by fish and tadpoles of the genus Rana. The common benthic fish were Noemacheilus denisonii, N. everzardii, Barilius gatensis, Garra jerdonii and young Tor khudree.
The abundance of various groups of insects and other benthic invertebrates depends much on the habitat they have colonised. Almost all torrential streams flowing at an altitude of 1500-2000 m harbour several species of Ephemeroptera, Plecoptera, Trichoptera and nematoceran Diptera, many of which are adapted to different niches available in streams. Two factors appear to be of major importance for benthic organisms: flow velocity and transport of the substratum downstream. The flow and substratum are closely interdependent (Sehgal, 1988).
The majority of the streams in the Western Ghats do not show zonation of water quality parameters and biota as observed in the Himalayan streams (Sehgal, 1988). Most streams in Ghats have an extremely short run from their source to the plain. The streams are short-lived and do not flow through tumultuous courses or through deep ravines. The streams lack large-sized fish except in the Bhadra where large Tor khudree are captured (Boote, 1979).
The present geographical distribution of fish species in the Western Ghats along these ranges suggests the likely migratory routes of coldwater fish. Hora (1947) suggested that many upland fish species migrated to the Western Ghats along the Satpura mountains which were probably continuous with the Eastern Himalaya in the past. Day (1865; 1876-1888) was the first to give an account of fish fauna of the Western Ghats. This was followed by many other publications, the more recent being those by Silas (1951; 1953), Rajan (1955) and Johnsingh and Vickram (1987). Based on their distribution in the Western Ghats, coldwater fish are divided into three groups, namely (a) those in the Deccan Trap area from the Tapti River down to16oN latitude at about the level of Goa; (b) those in the area extending from 16oN latitude southwards including the Malnad Division of Karnataka, the Nilgiris, etc.; and (c) the fish group of the Anamalai, Plani and Cardomom Hills in Tamil Nadu and Munnar High Range in Kerala. The Palghat Gap constitutes the dividing line between the Central and Southern groups. 102 species belonging to 39 genera and 14 families are known from the uplands of the Western Ghats. Most of them are of small size and are captured by subsistence fisherfolk. Various species of cyprinids of the genera Labeo, Cirrhinus, Puntius and Tor contribute to commercial catches in the rivers and their principal tributaries, lakes and reservoirs. Tor is an important sport fish, especially in the Cauvery. The exotic fish in the Western Ghats are Cyprinus carpio, Carassius carassius, Tinca tinca, tilapia Oreochromis mossambicus and the rainbow trout Oncorhynchus mykiss (golden and ordinary strains). Table 1 lists the fish recorded from the uplands of Western Ghats.
Both commercial and recreational fisheries are practised in the Western Ghats. Commercial catches are taken from the main rivers when they meander through plains, and from some lakes and reservoirs. Cast nets are commonly used for subsistence fishing. Since headwater streams are not fished commercially no information on catch per unit effort (CPUE) is available. The cast net catches are disposed of locally and not recorded. There is, however, some information available on sport fishing, especially for the endemic mahseers Tor khudree and T. mussullah, and on the exotic rainbow trout.
The past information on mahseer fishing in the Western Ghats is primarily based on the result of a Trans World Fishing Expedition (TWFE), which took place in 1978, and on Boote Mission which took place the same year. The Expedition was arranged by the Indian Tourism Development Corporation in collaboration with Air India. The team visited a number of regions in the country in search of the big mahseer. It collaborated closely with the Wildlife Association of South India (WASI) at Bangalore. It was at the time of a sharp decline in catches of large mahseer that the National Commission on Agriculture recommended a comprehensive survey of rivers and streams known to have mahseer stocks. In 1976 WASI leased about 22 km of the
Cauvery, 60-80 km distant from Bangalore, for conservation of Tor khudree. In 1978 TWFE fished for more than three weeks in the vicinity of Bluff or Sivasamudra, Sangam and at the Moshelli Halle. The team caught specimens of T. khudree ranging from 13.6-30.8 kg in weight at Bluff by using ragee paste (staple millet grain of Karnataka). At Sangam, within two weeks the experimental fishing with ragee paste captured 10 fish weighing 4.0-8.0 kg. Subsequently the team shifted to Ounti Gundu. Several specimens weighing 8.0-12.0 kg were caught including two fish of 20.4 kg and 22.4 kg respectively. The biggest mahseer of 32.0 kg was captured at Moshelli Halle. The Boot Mission fished during the period August-November 1978.
Recently, Shanmukha (1996) has reported about the success with fishery management of Tor khudree in the Cauvery. For a number of years WASI has been stocking the leased stretch of the Cauvery with mahseer fingerlings. Today the fishing season is open to licenced sport fishermen from October to May. Only rod and line fishing is allowed. Any captured mahseer has to be carefully unhooked and after recording its length and weight it must be released. There is a ban on using dynamite and poison. Fishing is permitted between 6 am and 6 pm only. The anglers are provided with approved guides of WASI. Records of catches are carefully maintained. Between 1989 and 1996 the large-sized mahseer captured by anglers ranged from 21.6 kg to 48.1 kg. Mahseer stock in this carefully managed stretch of the Cauvery is now protected against overfishing, with large-sized mahseers available to licenced sport fishermen.
The Coorg Wild Life Society, Madikere, is another voluntary organisation which is engaged in protecting mahseer fishery in the Cauvery, with a lease on 28 km of this river. This Society has been stocking young mahseer in this stretch since 1993. It also organises sport fishing and maintains fish catch statistics. The anglers are governed by similar rules and regulations as followed by WASI.
Since 1970 the Tata Electric Companies (TEC) fish seed farm at Lonavla, Maharashtra, has carried out artificial propagation, rehabilitation and conservation of Tor khudree, Tor tor, and Tor putitora. In the 1970s both T. khudree and T. tor were successfully bred using hypophysation. Successful artificial breeding of Tor putitora, a Himalayan species, was achieved in the same fish farm in 1995 and 1996 (Ogale, 1997).
The Department of Fisheries, Government of Karnataka, has procured about 150,000 of advanced fry/fingerlings of Tor khudree from TEC's fish farm and released them in the River Cauvery. The Fish Farmers Development Agency, Yadavagiri, Mysore, has also released 30,000 young mahseer into this river (Shanmukha, 1996).
The above activities show the results of the implementation of the project of the Department of Fisheries, Karnataka, launched in 1987: "Rehabilitation and Development of Mahseer Fishery in the Rivers and Reservoirs of Western Ghats". As a part of the programme a 5 ha mahseer hatchery has been constructed to produce 500,000 mahseer seed for stocking rivers and reservoirs in the region.
The catch data maintained by the Coorg Wild Life Society and by WASI, show that mahseer is now regularly captured, with a range from 3.3 kg to 48.1 kg. The above societies are protecting mahseer fishery by adopting conservation, stocking and management measures so as to stem the decline of mahseer stocks. In 1996, the construction of another 5 ha hatchery was initiated by the Karnataka Power Corporation Ltd. This hatchery also hopes to produce other endemic fish species for stocking alongside mahseer. Indian trout (Raiamas bola) is believed to have excellent potential to become a sport fish in streams and rivers of the Western Ghats where mahseer is not common. This fish can now be easily propagated on those lines adopted for mahseer (Khan and Abidi, 1994).
The other important species which provides sport to the fishing community is the exotic rainbow trout. It is present in streams of the Bababudan Range in Karnataka, in Nilgiris and Palni Hills in Tamil Nadu and in High Range in Kerala. It was perhaps the Nilgiris Game Association which took the initiative of stocking the streams of the Blue Mountains and threw them open to fishing. Subsequently trout was introduced in the streams of Palni and High Range by the Palni Hills Game Association and the High Range Angling Association respectively. The introduction of rainbow trout in Karnataka is restricted to Shankar Falls in the Kamengundi Range which were stocked with 1000 fingerlings in 1977. This stocking was done on recommendations made by Sehgal (1971b) after studying the ecology of this stream. The Annual Report of the Fisheries Department of the Government of Karnataka for 1978-79 mentions that rainbow attained 240 mm in total length and 140 g in weight in a one-year period.
Menon and Krishnamurthi (1955) reported that the decline in catches and average size of rainbow had started in 1913, i.e. four years after their introduction in the streams of Nilgiris. The possible factors as analysed by the two authors were (a) slightly acidic to slightly alkaline nature of stream water; (b) migratory type of strain, i.e. steel head sea-run; and (c) paucity of natural food in the streams. The analysis of creel census data from 1936 to 1952 revealed that the trout in nine streams of the Nilgiris had not shown an appreciable decrease in average size. It remained around 180 g in weight on an annual average basis. The catch per rod in relation to fishing pressure showed a decline from 12 fish to 3.6 fish between 1936 and 1943. From 1944 until 1952 there were narrow fluctuations in catch per rod. There was, however, a marked decrease in catch per angler between 1936 (12 fish) and 1952 (6.6 fish).
The true stream fishing for trout is carried out in the Lakidi and Deverbetta streams which empty into Upper Bhavani Reservoir. In 1967-1970 the average size of rainbow ranged between 290-403 g in Lakidi against 321-386 g in Deverbetta. The data revealed that an increase in fishing pressure resulted in a fall of the average size in both streams. The maximum size of rainbow caught during 1967-68 to 1969-70 was 2.2 kg in Lakidi against 0.4 kg in Deverbetta stream. There is no published account available on the trout catches in the Palni Hills. Kuruppan (1989) did not mention trout catches for the Nilgiris and Palni Hills.
The creel census data for the High Range, Kerala, published by the High Range Angling Association for 1968-69 season gave only the total number and weight of fish caught in each water body. The High Range waters previously owned by the Kannan Devan Hills Produce Company, were subsequently taken over by the Government of Kerala in the 1970s. Tea estates in this area are at present owned by the Tata Tea Company. From 1964-65 to 1968-69 the average size of rainbow ranged from 207 to 398 g in Kanniamallay and Silent Valley streams and from 110 to 192 g in Eravikolam and Rajamallay streams. The maximum fishing pressure during this period was exerted on the Rajamallay stream, where the average weight of captured trout declined from 192 g in 1964-65 to 110 g in 1968-69. There is no further published account available for the post-1970 period.
Subsistence fishery captures medium-sized fish Barilius gatensis, Puntius carnaticus, P. sarana, Labeo spp. Cirrhinus fulungee, Crossocheilus latius, Garra spp., Mystus malabaricus, M. vittatus, Xenentodon cancila, Channa gachua and Mastacembelus armatus. Since these species do not grow to a large size in mountain streams, the CPUE is only 300-700 g. The catches are sold by the subsistence fisherfolk in the nearby small towns or cities, as well as consumed by the fisherfolk families. There are no fish landing centres in the upland coldwater zone of the Western Ghats.
The Western Ghats have a number of lakes and reservoirs. The most important natural lakes are the Ooty (2500 m altitude, 34.0 ha) in Nilgiris, and the Kodai Kanal (Kodaikanal) (2285 m, 26 ha) and the Berijam in the Palni Hills. All lakes are situated in the state of Tamil Nadu. Two smaller lakes, the Divicolam (6.0 ha) and the Letchmi Elephant (2.0 ha) are in the Munnar High Range, and Lake Yercaud (1340 m, 8 ha) in Shevaroy Hills. Since the majority of streams draining the Western Ghats and joining the Krishna and the Cauvery rivers carry water during monsoon months only, they have been dammed for hydroelectric and irrigation purposes. The major reservoirs are: Lonavla and Walwahn in Maharashtra; V.V. Sagar, K.R. Sagar and Tungabhadra in the Malnad area of Karnataka; Mettur, Upper Bhawani, Mukurti, Parson's Valley, Porthumund, Avalanche, Emarold, Pykara, Sandynulla and Glenmorgan in Tamil Nadu; and Kundallay and Maddupatty in the High Range of Kerala. Of these the Lonavla, Walwahn, Upper Bhawani, Mukurti, Parson's Valley, Porthumund, Avalanche, Emarold, Pykara, Sandynulla, Glenmorgan, Kundally and Madupatty are important for their commercial and sport fisheries for trout, mahseer and common carp.
The small lakes in the Nilgiris, Palnis and High Range and Shevaroy Hills receive much of their water during the monsoon months. These lakes are formed in shallow depressions, usually round, oval or kidney-shaped. They range from oligotrophic to eutrophic, and from monomictic to polymictic types. Their surface water temperature during March-April ranges between 21.0 and 24.0oC. The following water quality parameters have been recorded: pH 7.3-8.2, dissolved oxygen 6.0-6.8 mg l-1, total alkalinity 82-158 mg l-1, and silicates 0.48-0.62 mg l-1 Table 2). Lake Ooty is now heavily silted and polluted by sewage overflowing from the drains passing along its shore (Jana, 1998).
Lake Ooty and Lake Kodai Kanal have moderate to dense growth of macrophytes of all types. Lakes in the High Range (Devicolam and Letchmi Elephant) are turbid with very few macrophytes. In lakes with macrophytes the shoreline has a belt of mainly Typha and Scirpus, and the littoral has rooted floating macrophytes such as Potamogteon and Nymphaea. Some lakes have the floating Eichhornia and Azolla and submerged Ceratophyllum and Hydrilla. In Lake Ooty and Lake Kodai Kanal the littoral zone is rich in periphytic biota associated with macrophytes. Diatoms, protozoans and rotifers are also associated with macrophytes. The littoral also harbours many aquatic insect larvae and adults, molluscs, cladocerans and the fish Danio aequipinnatus, Rasbora daniconius and Gambusia affinis. In Devicolam and Letchmi Elephant lakes the water remains turbid and lacks macrophytes in the littoral zone. The limnetic zone is rich in phytoplankton but poor in zooplankton. Fish are represented mainly by rainbow trout and common carp. Jana (1998) gives information on the fish yield of some lakes: in Lake Ooty fish yield was 75 kg ha-1 yr-1, in Lake Yercaud 31.6 kg ha-1 yr-1, in Lake Kodai Kanal 5.3 kg ha-1 yr-1. However, this information may be of only historical value as Jana obtained it from literature sources over 20 years old. Jhingran and Sehgal (1978) provided the following data on annual yields of common carp for three lakes for the period 1965-66 to 1973-74: Ooty - 4.8-6.1 t (141-179 kg ha-1); Sandynulla - 3.6-6.2 t (10.3-17.9 kg ha-1); and Pykara - 0.9-1.0 t (2.1-2.4 kg ha-1).
There is no information available on the Lonavla and Walwahn groups of hydroelectric reservoirs in Maharashtra. Reservoirs in the Nilgiris and High Range range in size from 10 to 2000 ha. Sreenivasan (1968) and Sehgal (1971; 1971a) reviewed the limnology of some lakes and reservoirs in the Western Ghats (Table 2). Many reservoirs are used for irrigation. The reservoir water has a low surface temperature, low alkalinity, and medium to low hardness. The values of dissolved oxygen ranges from 6.2 to 8.0 mg l-1. Phytoplankton is represented mainly by Bacillariophyceae, Myxophyceae and Chlorophyceae, and zooplankton by rotifers, cladocerans and copepods.
The fish catches in reservoirs comprise mainly of the rainbow trout and common carp. The past creel census data on rainbow fishing in Emarold, Avalanche, Mukurti and Upper Bhawani reservoirs show that an average catch of 545 g/rod/hour in 1966-67 dropped to 212 g/rod/hour in 1969-70 (Jhingran and Sehgal, 1978). In the Deviolam and the Letchmi Elephant lakes the average catch per rod per hour in 1968-69 was 233 g and 217 g respectively, as compared to 141 g and 151 g in Madupatty and Kundally reservoirs, respectively. Information on creel census of these water bodies for the subsequent years is not available
Aquaculture in the uplands of the Western Ghats is confined primarily to fish farms owned by the states concerned. They are involved principally in production of rainbow trout and common carp for stocking and aquaculture. The aquaculture of different species of trout, namely brown trout and rainbow trout, dates back to the mid-1800s and the beginning of the twentieth century when some devoted anglers and fisheries department officers transplanted eyed eggs of these species from Europe and elsewhere. Jhingran and Sehgal (1978) gave a detailed account on the history and introduction of brown and rainbow trout in the states of Tamil Nadu and Kerala. The first attempt to introduce trout was carried out in 1863 (Day, 1873) without success. Brown trout and Loch Leven trout (Salmo levensis) failed to establish themselves in spite of repeated transfers from the UK over four decades. In 1909 Mr. H.C. Wilson gave preference to rainbow over brown and established a trout farm at Avalanche in the Nilgiris. The eyed eggs were imported from New Zealand. In addition, fingerlings from Sri Lanka were brought and stocked in one of the streams of the Nilgiris. Another batch of eyed eggs was brought from Kashmir during the 1920s (Molesworth and Bryant, 1921). In 1943 rainbow trout was released in streams of the Palni Hills. In 1968 eyed eggs of golden rainbow, ordinary rainbow, tiger trout, brown trout and Kokanee salmon (Oncorhynchus nerka) were brought from Japan. Of these new releases, only golden strain of rainbow survived and established itself as a dominant strain of rainbow in anglers' catches (Kuruppan, 1989).
The introduction and development of aquaculture of trout in Munnar High Range, Kerala, commenced in 1909 with the importation of eyed eggs of brown trout. It did not succeed. The preference was switched over to the rainbow brought in from Sri Lanka, and by 1941 a trout farm was established at Eravikolam, followed by another one at Rajamallay. More recently, these hatcheries in High Range were taken over by the Tata Tea Company.
The main objective of the aquaculture of rainbow trout in the Western Ghats is to meet the requirements of the sport and recreational fishery. Fry and fingerlings are produced for release in streams, lakes and reservoirs. Each hatchery has a few brood ponds and rearing ponds for fry and fingerlings. A hatchery usually has a capacity to rear about 100,000 eggs (Jhingran and Sehgal, 1978). Sehgal (1971a) noted that from 1965 to 1970 the average percentage of hatching success ranged from 16.9 to 67.4%. The fish are fed mostly on wet diets consisting of egg yolk, bovine liver and dry fish. One hatchery produces annually between 12,350 and 80,000 fry for release. The rate of recovery is unknown. Efforts to cross-breed the golden and ordinary strains at Avalanche have given encouraging results (Subba Rao and Chandrasekharan, 1978). A one-year-old hybrid has been reported to attain 170 g against 90 g of the ordinary strain.
Rajamallay hatchery on the High Range comprises 3 brood stock ponds, 3-4 fry rearing units and a small hatchery to rear 48,000 eggs. During 1968-69 about 25,000 fry were produced and stocked in different waters. The performance of the hatchery in terms of the survival rate was better (54.5-63.6%) than that of the Avalanche hatchery. It is estimated that during 1941-67 about 340,000 fry were stocked in streams and lakes of the Munnar High Range, and the recovery rate was 13.7%.
The aquaculture of mahseer (Tor khudree) is carried out at Lonavla in a privately owned hatchery of the Tata Electric Companies. The brood stock is collected from the Walwahn and Shirawta reservoirs during July-August using gill nets near the main inlet of these reservoirs. Ripe spawners are selected and stripped, and eggs artificially fertilised. The fish from these reservoirs weigh between 700g and 900 g and the number of eggs per female ranges from 600 to 8200. The hatching rate is 20-90% (Kulkarni and Ogale, 1986). Some induced breeding of pond-reared Tor khudree at Lonavla is done without hypophysation (Kulkarni, 1990). Kuruppan (1989) reported success with releasing Lonavla fry of 10-15 mm total length in the River Moyar in the Nilgiris.
Investigations on the effect of formulated diet on growth and survival of Tor khudree in experimental cemented tanks have shown that at 40% protein level the daily increment was 1.4-1.5 mm in total length and 0.41-0.51 g in weight. The percentage of survival was 93-95% when fish were fed pellets containing fish meal and de-oiled silk-worm pupae, as compared to 77-84% in fish fed on diets containing leaf protein and shrimp waste (Srikanth and Keshavanath, 1986). In an experimental diet of Tor khudree 17-alpha methyltestosterone at 7.5 mg/kg concentration is reported to induce the maximum growth rate (Keshavanath et al., 1986).
The Krishna and Cauvery rivers receive numerous streams which arise in the uplands of the Western Ghats. Also, in the Western Ghats there are a number of shallow lakes and reservoirs which were created to supply water for irrigation and for the production of hydroelectric power. Most of the streams are not very productive and they serve mostly only for subsistence and recreational/sport fishing. Fish species diversity diminishes with increasing altitude, with a major drop in numbers above 500 m. Altitudes above 1500 m have a negligible number of fish species. In spite of that rivers and streams of the Western Ghats provide stable habitats for coldwater fish as most of them contain water throughout the year
102 species of fish are at present listed for the Western Ghats water bodies between 750 and 2000 m altitude. The majority of them are of small size and support only subsistence fishery. In the foothills medium-sized cyprinids such as Puntius and Labeo support a modest level subsistence fishery. Commercial and sport fisheries target the endemic mahseers Tor khudree and T. mussulah, and the exotic rainbow trout and common carp. The mahseer catches have been declining on account of over-exploitation of all sizes of fish using every possible catching method. The situation has been further aggravated by ecological degradation of water bodies due to human pressure and changes in land use. The efforts of the Wildlife Association of South India (WASI), based in Bangalore, have led to a remarkable improvement of mahseer stocks in a selected stretch of the Cauvery River. This voluntary association has been regularly stocking the leased 22 km of the Cauvery River with seed from the hatchery of the Tata Hydroelectric Companies at Lonavla, Maharashtra. Similar efforts by other fishing clubs and fishery associations have also been initiated, and as a result there is now a thriving, but firmly controlled recreational and sport fishery for mahseer in some parts of the Cauvery River.
The introduction of rainbow trout in the cold waters of Nilgiris, Palni Hills and High Range has been very successful, and in several water bodies the species has developed self-sustaining populations. There has been, however, a steep decline in its size, indicating that the fish is under a heavy fishing pressure. Some trout hatcheries have been poorly managed, and there is also need for more hatcheries which would be nearer to stocking sites. Another constraint is the shortage of a good quality pelletised feed. More effort should be spent on developing feed based on local ingredients (Ramakrishna, 1987).
Regarding future development of trout as a sport, the evidence so far indicates that interest in angling is growing. Recreational fishery is still insufficiently regulated. In streams draining the High Range (Rajamallay) and Palni Hills (Kolanaar, Pollavachi and Gundar) the fishing pressure is too high, with most of the angled trout below the minimum legal size. Regulations for trout fishing need to be revised, if necessary, to ensure a high and sustained fish yield to anglers. In the future finances and manpower should be made available to ensure that the increase in demand for angling is satisfied through a better management of the existing fish stocks and their enhancement through regular stocking.
The increasing instability of stream beds is also interfering with trout, and protection of catchments, especially prevention of erosion and siltation of streams, needs to be paid close attention by the responsible authorities, fishing clubs and associations. Conservation, including protection of spawning fish from poachers and of spawning beds, should be given priority.
Selected lakes and reservoirs with favourable conditions should continue to be regularly stocked.
There is little evidence of ill-effects of trout on other fish species of streams and lakes of the Western Ghats. Waters stocked with trout had no local fish of commercial or sport importance prior to trout introduction. The endemic fish fauna consists mainly of small-sized cyprinids and cobitids which are prey fish for the introduced species.
Indian trout (Raiamas bola) is another potential candidate fish species for stocking upland waters of the Ghats. This fish can now be easily propagated on those lines adopted for mahseer, and it could be introduced where mahseer is not common (Khan and Abidi, 1994). The fish would probably be welcomed by sport and recreational fishermen.
The Western Ghats also offer an opportunity for developing intensive culture of common carp. This would improve fish supply to the people living in the montane region. Karnataka, which has a silk industry, could supply de-oiled silkworm pupae as carp feed. Fish yield in some oligotrophic reservoirs and lakes could also be augmented by fish cage culture.
The author wishes to thank Dr. Shyam Sunder and Dr. H.S. Raina for his critical comments on the manuscript.
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