By
K.L. Sehgal
NRC on Coldwater Fisheries (ICAR)
Haldwani-263 139, Distt. Nainital (U.P.), India
Culture of coldwater fish in the Indian Himalayas has largely concentrated on the production of stocking material for rivers and streams, and some lakes. Until recently, brown and rainbow trout and common carp highly dominated the fish cultured for fish seed production, and to a much lesser extent for table fish production. In the 1990s, a major rehabilitation of rainbow trout culture was implemented with Norwegian assistance. Patlikuhl hatchery in Himachal Pradesh is now producing 10 t of table-size trout for the market, and stocking material for streams. At trout farms in Kokernag (Kashmir) and Katrain (Himachal Pradesh), high yielding strains of rainbow trout have been introduced. Common carp seed is produced in state fish farms for pond and rice-cum-fish culture and for stocking lakes and reservoirs in all Indian Himalayan states. Success was achieved with articificial breeding of the indigenous cyprinid mahseers (Tor putitora and Tor tor) and schizothoracines (Schizothorax richardsonii, S. niger, S. plagiostomus, S. planifrons, S. curvifrons, Schizothoraichthys esocinus). Mahseers, produced in hatcheries, are already being stocked in some Himalayan rivers. More work still needs to be done to have a reliable technology for producing fully viable schizothoracine fingerlings for regular stocking.
In the Indian Himalayas the cultivation of fish contributes little to the overall freshwater fish production. Virtually every facility created for fish cultivation in the Indian Himalayas produces fish for stocking streams and lakes primarily to meet the requirements of sport fishing. Commercial fishery is also dependent to some extent on the stocking of lakes and reservoirs with fry and fingerlings. While for a number of years fish hatcheries in the Himalayas have been raising eyed-eggs, fry and fingerlings of brown and rainbow trout, and fry and fingerlings of common carp for stocking, only recently have some hatcheries started producing seed for stocking the indigenous mahseers and schizothoracines. To meet the ever-increasing demands of angling, subsistence and commercial fisheries, there has been a need for modernisation of some hatcheries, as past neglect has resulted in a decline in seed production. Some hatcheries have had to be abandoned. The degradation of hatcheries took place especially where water quality deteriorated and the silt load in streams increased. This chapter discusses the farming of coldwater exotic and indigenous fish and the current developmental activities which can be considered as a turning point in coldwater fisheries of the Indian Himalayas.
Coldwater aquaculture in the Indian Himalayas has been closely associated with the introduction of exotic trouts and common carp. The lack of fast-growing indigenous fish in the Himalayas motivated the British administrators in India to transplant exotic species, such as trout and other salmonids, from Europe to meet their need for recreational fishing. The fate of transplanted coldwater species is well documented, and more recently it has been summarised by Sehgal (1989).
The first attempts to bring brown trout eyed-eggs from England into India were made by Mr. F.J. Mitchell in 1899 and 1900 (Mitchell, 1918). They came from Howeiton in Scotland, and the eggs successfully hatched in a small trout hatchery at Harwan in Kashmir. This hatchery had the capacity to rear 100,000 eggs. In 1905, in Kashmir, the first batch of eggs were obtained from the stock which had been produced from the Scottish eggs. This was the beginning of the spread of brown trout in the Himalayas and elsewhere. From Kashmir the species was taken to Jammu, Gilgit, Himachal Pradesh, Uttar Pradesh, North Bengal, Arunachal Pradesh, Meghalaya and Nagaland in India, and to Abbottabad and Chitral in Pakistan. Mitchell (1918) also succeeded in bringing and successfully rearing the steelhead strain of rainbow trout from England. Of of the two species of trout, brown has become domesticated in culture systems, streams and lakes, and has emerged as a self-sustaining population in the Himalayas. The rainbow trout, however, has remained confined to pond culture and is not established in streams and rivers of the Indian Himalayas.
Attempts to introduce other species of salmonids to Kashmir are of a more recent date. In the 1960s eastern brook trout (Salvelinus fontinalis), splake trout (cross between the lake trout Salmo trutta lacustris and eastern brook trout), both from Canada, and land-locked salmon (Salmo salar) from the USA were stocked in Kashmir fish farms. These species were received as gifts by the Kashmir Government through diplomatic missions of these countries. The eastern brook and splake trouts suffered diseases and were lost. Poor results were obtained from attempts to breed land-locked salmon and this species did not survive. In the 1980s another strain of rainbow trout was introduced at the Kokernag fish farm in Kashmir under an EEC-assisted programme.
In Himachal Pradesh the eyed-eggs of brown trout were brought to Kulu and Kangra Valleys and Chamba of Himachal Pradesh from Kashmir (Howell, 1916). Regular releases of eyed-eggs in the upper stretches of Ravi and Baner Awa and Binun (=Binwa) tributaries of the Beas River between 1912 and 1947 met with little success. The failure of brown trout to establish itself in Kangra Valley is primarily due to a limited availability of suitable stretches of streams and the lack of suitable pools where fish could seek shelter during high floods when these streams become raging torrents. In Kulu Valley, introduction of brown trout commenced in 1909-10 when eyed-eggs successfully hatched at the Mahili hatchery, Katrain. From Katrain brown and rainbow trout were transferred to Chamba, Barot, Chirgaon and Sangla trout hatcheries. In 1993, of the five existing trout farms located at Barot, Patlikuhl, Sangla, Nagni and Mahili, the last two were being reconstructed (Anon., 1993).
In the state of Uttar Pradesh trout transplants of eyed-eggs were successfully hatched in the Garhwal region at Talwari and Kaldhyani hatcheries and produced stocking material for the Pindar, Birehi and Asiganga streams of the Ganga system.
Attempts at establishing brown/rainbow trouts in the eastern and northeastern Himalayas in the early part of the 20th century met with little success. The main reason was that a majority of the streams carry a heavy silt load. This part of the Himalayas is a heavy rainfall zone. In 1989 (Anon., 1989) Arunachal Pradesh was the only state in the northeastern Himalayas in India in which brown trout was cultured and stocked in streams for sport fishing. The total capacity of hatcheries in 1989 was between 20,000 and 50,000 eyed-eggs. The seed was also supplied to the Nagaland where it was released in one stream in the 1970s, and in the Meghalaya. Fish seed banks for Tor tor, Tor putitora and Acrossocheilus hexagonolepis were opened at Roing, Namsai and Seppa to provide stocks for releases into the three major Indian tributaries of the Brahmaputra, i.e. Kameng, Lohit and Dibang. Fish seed is reared to fingerlings, but the growth rate of these species is slow. On the Apatani Plateau of Arunachal Pradesh, which is situated at an altitude of 2000 m, there are 490 ha of rice fields available for paddy-cum-fish culture. In 1989 a hatchery at Ziro aimed at producing 3 million common carp fish seed for this purpose (Anon. 1989). Brown trout is also established in Sikkim, which has one trout farm.
The mixed stock of three phenotypes (scale, mirror and leather) of common carp (Cyprinus carpio) was introduced in India for the first time in the Nilgiris (Western Ghats) from Sri Lanka in 1939. From the Nilgiris it was transferred to Bhowali hatchery in Uttar Pradesh, and to the Kumaon lakes in 1947 and subsequent years. From Bhowali it was then introduced to Himachal Pradesh at Nahan, Sirmur district.
During floods of 1971 silver carp (Hypophthalmichthys molitrix) was washed out into the Sutlej River from a fish farm at Deoli, and eventually it reached Gobindsagar Reservoir. Grass carp (Ctenopharyngodon idella) was stocked in a few lakes of the Kumaon Himalaya.
Today, the available technologies allow the culture of a number of exotic and indigenous coldwater fish species in the Indian Himalayas. The most common exotic species are rainbow trout, brown trout, common carp, while the indigenous fish are: mahseers (Tor putitora and Tor tor), and schizothoracines (Schizothoraichthys esocinus, S. progastus, Schizothorax richardsonii, S. niger and S. curvifrons). Among these Tor putitora, S. progastus and S. richardsonii are preferred because of their wide range of distribution in the Himalayas.
The distribution of rainbow trout worldwide attests to its ability to adapt itself to a variety of aquatic environments, including aquaculture conditions. Rainbow trout can be propagated artificially, which is important for its production as food fish. The fish can be fed artificial feed and withstand temperatures of up to 26.6oC for short periods. It also tolerates low dissolved oxygen content of water, is resistant to some fish diseases, and grows fast. In open waters, water temperature and precipitation are the primary factors affecting the survival and production of naturalized populations. The optimum thermal regime for the species lies in the range of 12-20oC (Graham, 1949), and the annual precipitation and freshets are important.
Golden mahseer (Tor putitora) is a widely distributed fish, present from Hindukush-Kabul-Kohistan in the northwest to Sadiya in the eastern Himalayas, as well as in Myanmar and Thailand. The species, a multiple spawner, migrates annually upstream to a higher altitude to feed and spawn. In the streams of Himachal Pradesh it is a herbivore. The following major food items are encountered in its guts: diatoms (47.3%), green algae (13.3%), insect larvae (10.2%), copepods (3.2%) and detritus (22.3%). The remaining percentage (3.7%) includes protozoans, rotifers, etc. The fry and fingerlings can be raised on wet and dry artificial feeds.
The snow trout or mountain barbel (Schizothorax richardsonii) is widely distributed in the Indian Himalayas, from Ladakh in the northwest to Sadiya in the east. The species is an inhabitant of snow-melt and glacier-fed streams in the Greater and Lesser Himalayas. They undertake migration during winter months when the temperature in the Greater Himalayan waters reaches the near-freezing point. This induces them to migrate downstream and frequent the warmer spring-fed streams in search of suitable spawning grounds. The optimum temperature for spawning is 18-21.5oC. Hypophysation has failed to induce spawning. The mouth of S. richardsonii is ventrally placed, traverse, lower lip is well developed, with a free posterior edge forming an adhesive sucker. The posterior edge may be concave. The inner side of the lower lip is covered with cartilage. The fish is a typical benthic feeder with a mouth well suited for rasping the microbiota growing over the bottom rocks, boulders, stones, etc. It subsists mainly on benthic microbiota. The early fry and fingerlings (15-65 mm in total length) consume mainly the larvae of Diptera, nymphs of mayflies and larvae of caddisflies (66.4%, 23.2% and 9.5% respectively). Fish of 85 to 105 mm total length consume primarily diatoms (66.6%), blue-green algae (11.9%), insect larvae (6.7%) and detritus (11.8%). Fish of 133 to 300 mm subsist mainly on diatoms (60%), blue-green algae (9.6%), green algae (8%), insect larvae (10.2%) and detritus (8.7%). Presence of gravel and sand in the gut is due to rasping the algal encrustations from stones and rocks. No published account is at present available on the biology of S. progastus.
The aquaculture of coldwater fish in the Himalayas is limited, considering the total area of this region and the vast resources of water. At the end of the 1980s only 63 ha (Table 1) were under aquaculture in an area of 594,000 km2.. The present status of aquaculture of trout, common carp, mahseers and schizothoracines is described as follows.
4.1 Trout
At the beginning of the 1990s farming of trout was being carried out on several fish farms in Kashmir (4), Himachal Pradesh (3), Uttar Pradesh (2), Arunachal Pradesh (1) and Sikkim (1). The siting of these aquaculture facilities was based on the availability of water in required quantity and quality, i.e. from rheocrene springs and snow-melt/glacier-fed streams. Table 2 gives the capacity for two hatcheries in Kashmir and four hatcheries in Himachal Pradesh. Most farms receive water supply from snow-melt/glacier-fed streams. The old facilities at Laribal, Harwan and Achabal (the last receiving seepage water of the Bringhi stream and hence not a true spring-fed facility) in Kashmir, Katrain in Himachal Pradesh, and Kaldhayani in Uttar Pradesh might have been established when the stream water did not have the present level of silt load. At present a heavy load of silt reaches these farms from February to September. This is the result of soil erosion in their largely deforested catchments. Only from October to January is the silt load low. This has adversely affected the performance of these farms. Even some of the more recently established facilities such as the Sangla hatchery, the Norwegian-assisted trout hatchery at Katrain in Himachal Pradesh, and the hatcheries in Sikkim and Arunachal Pradesh still face the same difficulty. Table 3 shows the water quality for some trout hatcheries in the Indian Himalayas.
Natural spawning and the time for egg stripping of brown and rainbow trout is related to the changing of the photoperiod. In Kashmir and Himachal Pradesh brown trout attains full maturity in mid-November to mid-December in farms receiving snow/glacier-melt water. In spring-fed farms it matures in December-January. In the central Indian Himalaya brown trout matures in December-January. Rainbow trout matures in mid-February to March. The average number of eggs per kilogram of female body weight varies between 1234 and 1342 in brown trout and 1649 to 1850 in rainbow trout. Research on Kashmir farms shows that the number of eggs can be enhanced by up to 14% if broodstock is kept in good condition. This includes separation of males from females three months prior to egg stripping, and feeding them a wet diet consisting of partially boiled fish meat balls made from common carp and schizothoracines in a ratio of 1:1. Such broodstock has a higher number of eggs (1417 to 1542), but the eggs are also of better quality, giving 89.2% survival from green egg to swim-up fry as against 25% in conventional practice. In Kashmir farms the conventional diet of trout consists of raw fish which results in nutritional deficiency.
During the incubation period trout eggs and alevins are prone to several diseases, and if left uncared for, there are heavy losses in trout farms of the Himalayas. Good maintenance of broodstock on a nutritious but conventional diet, careful handling of fertilized eggs, prophylaxis against fungus by flushing hatching troughs/trays with malachite green in a ratio of 1:2,000,000 for 30 minutes twice a week, providing enhanced water supply, 'thinning' of hatching trays at eyed and alevin stages, etc., have resulted in a 94% survival from green egg to swim-up fry, as against 30% in conventional practice. The wide application of the improved technology has resulted in achieving 80-90% success in several hatcheries in Kashmir, Himachal Pradesh and Uttar Pradesh.
Trout hatcheries in the Himalayan region are of moderate size, having the capacity to incubate 64,000-480,000 green eggs. After the swim-up fry emerge they are fed initially on emulsified yolk of hen's egg followed by a mixture of yolk of hen's egg and bovine liver emulsion in 1:1 ratio. After having learnt the acceptance of initial artificial feeds, the fry are transferred to outdoor nurseries. In the northwest Himalayan farms the emergence of fry of brown and rainbow trout coincides with spring rains and hailstorms. The hailstorms may chill the already cold water to a low temperature, which may lead to high mortality of the young fry. In March-April the snow /glacier-melt fed water containing fine silt is also detrimental to the survival of trout fry in trout farms. During the first three months the survival of fry fed on a diet of bovine liver and dry powdered silk-worm pupae, varies between 10.8-15.8%. Thus the principal factors responsible for fry losses are silt load, hailstorm-cooled water, diseases such as myxosporidiasis, octomiasis, ichthyophthiriasis, and nutritional deficiencies. Better quality feeds result in a survival from 50 to 61%, with maximum feed efficiency of 79.9% at 35% crude protein level (Sehgal et al., 1976).
Yearlings and 1+ age group are raised in growing ponds and raceways. Trout is fed there on a conventional diet consisting of local raw fish, mutton, slaughter house waste, dry silk-worm pupae, etc. The most serious loss of growing trout is due to nutritional imbalance and non-observance of prophylactic measures.
In the EEC and Indo-Norwegian projects in Kashmir and Himachal Pradesh respectively, efforts are underway to commercialize trout farming.
In 1988 the Norwegian Government came forward to assist the Himachal Pradesh state government to rehabilitate the exotic trout culture, as well as to commercialize trout production. The project, initiated in 1989, was executed in two phases: transfer of technology, and production phase. The transfer of technology stipulated construction of a modern farm trout on the Norwegian model, with capacity to produce 10 t of trout per year. Further activities included import of quick growing, disease resistant eggs, development of economically viable pelletised feed with locally available ingredients, training of local staff and farmers, and production of economically viable fingerlings to encourage the local farmers to adopt trout farming. Kumar (1992) reported the following achievements. The infrastructure was completed by April 1990, and the frst consignement of eyed-eggs of rainbow trout was received at Patlikuhl farm in April 1991. A feed mill was installed and started producing pelletised feed, with a production capacity of 500 kg per day. Four project personnel underwent training during the construction phase. The rearing results during the first year were excellent, with 92% survival rate for the eyed-eggs to the advanced fingerling stage.
38,000 fingerlings were stocked in a number of streams. In a period of less than one year the reared fish grew to a marketable size of 200 g. The second instalment of eggs from Norway was received in March 1992, and the sale of market-size trout produced at Patlikuhl farm started in the same month. The production target of 10 t was expected to be achieved in the same year. Based on the imported technology several other trout farms started being renovated. In the second phase it was expected to produce 100 t of trout annually in the state of Himachal Pradesh. At the same time the State Department of Himachal Pradesh also initiated genetic rejuvenation of brown trout (Kumar, 1992).
At trout farms in Kokernag (Kashmir) and Katrain (Himachal Pradesh), high yielding strains of rainbow trout have been introduced from Europe and are surviving well. The fish at Kokernag have started breeding. The Kokernag farm produces 3 million trout fingerlings annually (Mohan, 1996).
4.2 Mahseer
Mahseers (Tor spp.) of the family Cyprinidae are regarded as one of the best sport fish and also a sought-after food fish. In the Indian Himalayas, due to man-caused deterioration of the environment and overfishing, mahseer stocks have sharply declined. To rehabilitate this group of fish induced spawning and artificial propagation have been undertaken in order to contribute to the production of seed in hatchery conditions. The first efforts to induce-breed pond-reared Tor putitora were done at Dehra Dun by injecting pituitary extracts. The survival and hatching rates were extremely low (Sehgal and Kumar, 1977). Then a mature fish caught from Lake Bhimtal in the Kumaon Himalaya was stripped and fertilised using the `dry method', giving better results (Tripathi, 1977). The practice of catching natural fish stocks from Kumaon lakes for the purpose of egg-taking, artificial fertilization and hatching in wooden/G.I. trays continues to produce stocking material of Tor putitora (Joshi, 1982; Joshi and Saxena, 1989). The use of regular flow-through hatching troughs and trays and rearing units at the National Research Centre on Coldwater Fisheries in 1990 was successful. The hatchery at Haldwani now produces some of the stocking material for the Central Himalaya. The use of formulated diets to raise fry and fingerlings of Tor putitora in plastic pools and net cages anchored in Lake Bhimtal has shown that using dry formulated feeds containing 33.5 and 40.8% crude protein results in a feed efficiency of 39.4-62.5% compared to 35.2-36.7% with conventional food of mustard oil-cake and rice bran in a 1:1 ratio. The ingredients used to formulate the diet comprise a mixture of dried silkworm pupae, powdered soybean, wheat middlings, mustard oil-cake, maize flour, barley flour and buck wheat. The feeding is done at the rate of 8-10% body weight. The use of boiled and macerated yolk of hen's eggs gives 66-67.8% feeding efficiency with survival rate of 84-85% as compared to 56-78% with dry feed (Joshi, Sehgal and Malkani, 1989).
Presently, Tor tor and Tor putitora are bred on a small scale in Bhimtal (Uttar Pradesh), producing 50,000 fingerlings annually. There is a programme for the development of mahseer fishery in the Kumaon lakes Bhimtal, Sattal and Naukuchiatal, and mahseer fingerlings are also needed for the rehabilitation of stocks in the rivers Yamuna, Nayar, Kosi, Saryu and Ganga (at Rishikesh and Hardwar) (Pandey, 1996).
The Himalayan golden mahseer Tor putitora was successfully bred for the first time using ovaprim in Lonavla fish farm, situated in the state of Maharashtra in the Western Ghats. Mahseer fry, collected from wild waters of Himachal Pradesh in 1991, by the 1992 monsoon season had produced 500 fingerlings which were released in Lake Walwhan in Western Ghats. There they matured by the year 1995, when they were injected with ovaprim. This produced fertilised eggs, and subsequently fry. This was the first successful attempt in India to breed golden mahseer with ovaprim. The experiment was repeated on five females during the 1996 monsoon, resulting in approximately 20,000 fry. The fry of 1995 were transferred to Jammu to Anji fish farm, where they grew successfully to the fingerling stage (Anon., 1997).
4.3 Schizothoracines
The culture of schizothoracines is still in its experimental stage. Like the mahseers this group of cyprinids has shown a sharp decline in catches all along the Himalayas due to indiscriminate fishing and environmental degradation. While Das (1978) believes that the introduction of exotic common carp has adversely affected the schizothoracine fishery in the lacustrine environment of the Kashmir Valley lakes, Sunder and Subla (1984) are of the opinion that in the Jhelum River the presence of the common carp has had no impact on schizothoracines. But observations of Sehgal (1977) and Natrajan (1988) support the Das (1978) opinion. Sehgal (1974) started experiments with collection and artificial fertilisation of eggs from Schizothorax planifrons, S. curvifrons and S. plagiostomus. These fish make spawning runs from Lake Wular into two inflowing streams. Subsequently, egg-taking of S. plagiostomus and raising of post-larvae and fry was successfully carried out using mature specimens caught from several streams of Himachal Pradesh (Jhingran and Sehgal, 1978). Eggs of S. niger from Lake Dal were artificially fertilised and achieved a hatching rate of 10-40% (Vass et al., 1978). The result of induced breeding and artificial fertilization and incubation of Schizothoraichthys esocinus in a running water system gave cumulative hatching of 30-55%. Further rearing of S. esocinus to fry and fingerling on artificial feeds met with some success (Raina et al., 1986). There is still work to be done on schizothoracine seed production to achieve a fully viable fingerling stage ready for release into rivers and lakes.
4.4 Common carp
In the Himalayan region two German phenotypes of common carp (mirror carp and scale carp) are commonly produced in aquaculture. These species are cultivated primarily to produce seed for extensive pond culture and for stocking of lakes and reservoirs. Common carp is produced in fish farms of the State Fisheries Departments of Himachal Pradesh, Uttar Pradesh, North Bengal, Arunachal Pradesh, Meghalaya, Manipur and Nagaland. The majority of the farms are located in the Lower Himalaya and the Himalayan foothills (Siwaliks).
In the Indian Himalayas the common carp is successfully bred in cement tanks, in rectangular cloth containers fixed in ponds (hapas), and in earthen ponds. Since common carp eggs are adhesive and need a spawning bed, aquatic plants such as Hydrilla and Najas, palm leaves, dried pine and cedar needles and banana leaves, are used as a substrate in different parts of the Himalayas.
The period of incubation varies from 48 to 96 hours at 23oC, and 96-144 hours at 19.7-22.6oC. In Himachal Pradesh, the percentage of fertilization ranges from 84.7 to 96% resulting in a 65.8-85.9% hatching rate when Hydrilla is used as an egg substrate. In floating rafts made of dried pine needles, the fertilization ranges from 62 to 80% with a 45-63% hatching rate. Absorption of the yolk-sac takes 60-90 hours. In earthen nursery ponds organic manure (cow dung), at a dose of 10-15 t/ha, helps to produce natural food. The feeding of fry is carried out with a mixture of rice bran and mustard oil-cake in the ratio of 1:1 at 2-4% body weight. The survival of fry to fingerlings varies between 45 and 53% in different farms of Himachal Pradesh and Uttar Pradesh.
The culture of common carp in terraced paddy fields of Arunachal Pradesh and Meghalaya in the northeastern Himalaya is of a more recent date (Nayak and Mandal, 1989). While selecting the site for paddy-cum-fish culture, the availability of a moderate flow of 1-2 litres per second is desirable for the proper growth of common carp. Along the perimeter of a paddy field a canal 50 cm deep is dug. The paddy field is stocked with fingerlings at a stocking density of 6000 fingerlings/ha. In Meghalaya and Arunachal Pradesh the fingerlings grow to an average weight of 180 g. With the application of 2-3 tons of cow dung per hectare and supplementary feeding with rice-bran and oil-cake mixture at 4% body weight, the yield ranges from 186 to 800 kg per ha during the paddy growing period.
In the Himalayan waters of India aquaculture has so far failed to meet the demand for stocking material. Table fish production of coldwater species in fish farms is still on a very low level. The main constraints in developing commercial farms are lack of reliable data on cost-benefit, shortage of trained manpower, insufficient level of biological and engineering research, and shortage of credit.
The existing fish farms under the management of state governments also suffer from some further constraints. Some have defective siting and design, and there is shortage of funds to run them efficiently. Research in trout farming was begun in the late 1970s by the Central Government Research Centre under the Central Inland Fisheries Research Institute. At the beginning the Centre was short of funds for developing the required infrastructure. Most of the research carried out by this Centre was undertaken in the existing state farms after making modifications and alterations to meet the research requirements for generating experimental data. These constraints were recognized and steps were taken to develop a modern facility for research and development of various technologies and their transfer. This resulted in establishment of the National Research Centre on Coldwater Fisheries under the Indian Council of Agricultural Research, Government of India. The research efforts have already resulted in an increase in survival rates in trout hatcheries through improvement of water quality, disease prevention and development of compound dry feeds. The present priority areas are: stock improvement of brown and rainbow trouts through selective breeding, and trials of high-yielding strains of rainbow trout under Himalayan climatic conditions.
The availability of trout for sport fishery depends on the availability of a healthy stocking material of required size and quantity. This has to be produced in hatcheries. Some hatchery managers, in their effort to fulfill the quota, still prefer to stock young fry in the streams to avoid the high mortality rate in the hatchery, which would interfere with meeting the hatchery's annual targets.
At present trout is considered to be a highly priced fish in the Himalayas. Considering the demand for table trout in this country, which is said to be nearly 800 t annually for five-star hotels and restaurants in four metropolitan towns, improved aquaculture practices could go a long way towards alleviating the shortage. In the Himalayas a number of small rheocrene/limnocrene springs exist which could be used for the production of stocking material for the nearby streams. The development agencies should provide technical know-how, hatching troughs, eyed-eggs, etc. while rural youths could assist in such programmes, giving them a chance for employment. The fry raised under a barn house could be released into spring brooks which would act as nursing ground for the main trout stream (Jhingran and Sehgal, 1978).
The second species which is highly promising to develop as a relatively cheap food, especially in the Lower Himalaya, is common carp. The development agencies could provide funds to village authorities to create rearing facilities and to provide the necessary technical know-how to the fish farmer along with environmental awareness. This would assist in further expansion of common carp aquaculture. The increased seed requirement would be met by the State Fish Farms until private entrepreneurs take over. Kangra Valley in Himachal Pradesh has about 1000 kilometres of streams having perennial water flow and flat land along their banks. Construction of earthen ponds and canals could be done relatively cheaply but care should be taken not to construct earthern ponds on unsuitable soils to prevent seepage. Where there is a traditional silk-worm rearing industry, silkworm pupae would be available as feed for trout. Private companies in many parts of the country already offer pellets for Indian carps, which with some modification, could be used for common carp.
Fish production in some upland lakes and reservoirs could be enhanced by installing floating or fixed cages. The number of such cages should be regulated to avoid deterioration of water quality in such water bodies.
Aquaculture production of mahseer and schizothoracine fingerlings still needs to be perfected if the demand for stocking streams and lakes is to be met. The important seed collection centres for mahseers and schizothoracines have been identified in several river systems of the Himalayas.
The author wishes to thank Dr. Shyam Sunder and Dr. H.S. Raina for their critical comments.
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