by
Jiwan Shrestha
Post Box 7146, Kathmandu, Nepal
There are fifty-nine coldwater indigenous and two exotic fish species in Nepal. Among the 59 indigenous species, Neolissocheilus hexagonolepis, Schizothoraichthys spp, Schizothorax spp and Tor spp are the most economically important fish, considering their table fish and sport fish values. Their biology, behaviour and propagation is well known and understood. More effort is needed in the direction of developing a successful technology for their reproduction under controlled conditions. Wild stocks in cold waters of Nepal need to be better protected from over-exploitation and their management could be considerably improved. Due to the lack of other economic opportunities, such as agriculture, fishing may often be the only source of animal protein for the local people of hills and mountains of Nepal. Deforestation due to the lack of other fuel and fodder resources causes soil erosion and sedimentation problems, which negatively impact fish habitats including their breeding grounds. Further constraints are the presence of hydroelectric dams on some rivers, destructive fishing methods and discharge of untreated effluents. Government assistence is needed for development of coldwater aquaculture and in production of stocking material for cold waters, as well as for raising the awareness of the fisherfolk about the danger of fish stock over-exploitation and advising on sustainability of coldwater fish stocks. In 1995/96 the annual fish production in Nepal was 10,300 t.
Nepal is a land-locked country (Fig. 1). It possesses a large number of rivers with perennial water supply from melting snows of the Himalayas, considerable number of lakes, a few reservoirs, an increasing number of fish ponds and irrigated fields, as well as marginal swamps. All these are suitable for fisheries development. Substantial progress has been achieved in the fisheries subsector as His Majesty's Government of Nepal has given fisheries a priority during the last few decades. In its efforts it has been assisted by international agencies, including UNDP, FAO, ADB, JICA, IFAD. The fish production in the country has increased from 750 t/year in 1981/82 to 10,300 t/year in 1995/96. Presently, fisheries of Nepal account for about 1.5% of the agriculture share of the national gross domestic product. While warmwater fishery will remain the dominant fish production subsector in Nepal, coldwater fishery in mid-hill rivers, lakes and reservoirs is also being targeted for further development. This contribution reviews the situation and assesses the potential for such development.
The indigenous and exotic fish of Nepal total 186 species (Shrestha, J., 1995; Subba and Ghosh, 1996).They are distributed from the lowland plains (Terai), through the hills to the Himalayan mountains up to an altitude of approximately 4000 m a.s.l. In Nepal coldwater fish belong either to the family Cyprinidae or Salmonidae. Some coldwater fish species of Nepal may tolerate a wide range of water temperature, but most of them live in water with a temperature of 10o - 20oC. Such fish are found in mid-hill valleys, hill and mountain streams, and in lakes located at 600 m altitude and higher. The coldwater lakes of Nepal have a high dissolved oxygen level, low carbon dioxide concentrations, high transparency, low productivity and sparse vegetation. Streams usually have a high current velocity and are shallow, with stony bottoms. In the cold waters of Nepal capture fishery dominates, although cage culture is increasing in some lakes. There is little solid information on coldwater capture fishery, which is widely scattered and of subsistence character. Most of the captured fish are consumed immediately after being caught.
1.1 Geographical background
Nepal is situated between 26o20'-30o10'N latitude and 80o15'-88o19'E longitude. It borders on the Tibetan Autonomous Region of China in the north, and India in the south, east and west. Nepal covers an area of 147,181 square kilometres. It is divided into three parallel geographical zones running east to west: the Terai plain in the south, the hills (which are the foothills of the Himalaya) and the Himalayan mountains. The Terai plain is an extension of the Gangetic plains of India. The hilly area is located in the middle part of the country varying in altitude from 610 m to 4877 m a.s.l., with the lower hills up to 2700 m, and upper hills to 4877 m. The Himalayan mountains are located from above 4877 m, above the tree line. Mountains and hills cover 83% of Nepal while the Terai occupies only 17%.
The Himalayas in the north have an important influence on the climate of Nepal. The climate change from east to west is not very pronounced as the mountain system runs east and west. The climate change from south to north is very abrupt in response to the altitudinal variation (130 m in the south and 8848 m in the north). According to the altitude the country is divided into three climatic zones, i.e. subtropical in the Terai, temperate in the hills and alpine in the mountains.
The maximum air temperature during summer may reach 45oC in the Terai and about 20o in the middle hills. Average maximum and minimum temperatures in the Terai during the winter range from 23oC to 7oC, while in the valleys the temperature reaches a 12oC maximum and the minimum is below the freezing point.
1.2 Water resources
Inland water resources consist of river systems, lakes, reservoirs, village ponds and paddy fields. The main water resources for coldwater fish are rivers, lakes and reservoirs which comprise approximately 48.8% of the total water area of Nepal, with 49% being paddy fields, 1.4% swamps around irrigated fields, and 0.8% village ponds. Collectively, these water bodies cover nearly 3% of the total Nepal surface area, and it is estimated that some 500,000 ha of water surface may be available for fish production (Pradhan et al., 1966).
There are three major river systems in Nepal: Kosi in the east, Gandaki in the centre, and Karnali in the west (Table 1, Fig. 2). All three river systems drain into the Ganges in
Table 1. Water resources of Nepal
A. |
River systems | |
1. |
The Kosi River system (a) Tamar (b) Sun Kosi (c) Dudh Kosi (d) Indravati (e) Likhu (f) Tama Kosi (g) Arun | |
2. |
The Gandaki River system (a) Trisuli (b) Budhi Gandaki (c) Marsyangdi (d) Seti (e) Kali Gandaki (f) Madi (g) Myagdi | |
3. |
The Karnali River system (a) Budhi Ganga (b) Seti of west (c) Mugu Karnali (d) Thulo Bheri (e) Sanu Bheri (f) Humla (g) Tila | |
4. |
Other river systems (a) Mechi (b) Kanaki (c) Kamala (d) Bagmati (e) Rapti (f) Babai (g) Mahakali | |
B |
Lakes | |
1. |
Rara or Mahendra Lake | |
2. |
Phewa Lake | |
3. |
Begnas Lake | |
4. |
Rupa lake or Rupakot Lake | |
5. |
Khaptad lake | |
6. |
Tilicho Lake | |
7. |
Phoksundo lake | |
8. |
Dudh Pokhari | |
9. |
Panch Pokhari | |
C. |
Reservoir | |
1. |
Indrasarobar Reservoir, Kulekhani | |
India. Hydrologically, the rivers of Nepal can be divided into two major groups: rain-fed rivers, and snow- plus rain-fed or glacier melt plus snow melt plus rain-fed rivers (Shrestha, H.M., 1983). The seasonal fluctuation of discharge is very high, particularly in rain-fed rivers.
Rivers of shorter length are seasonal as they may dry up from time to time. Table 2 lists the length and fall of the major rivers of Nepal (Shrestha, H.M., 1983).
A number of rivers originate in the Himalayas and flow from north to south, being in flood when they receive the torrential rains of the monsoon and snow- and ice-melt waters. The rivers of Himalayas usually flow in deep V-shaped valleys. On entering the Terai the rivers deposit their sediment on floodplains.
Presently, only a few lakes are being used for fisheries. These are the lakes of Pokhara Valley, and several lakes in western Nepal. In Pokhara Valley, Lake Phewa is situated at an elevation of 742 m a.s.l., covers 523 ha and has a maximum depth of 24 m. It receives water from two spring-fed streams, Harpan and Seti Khola. Lake Bagnas situated at an elevation of 650 m a.s.l. covers an area of 224 ha and has a maximum depth of 10 m. The Syankudi Khola is its main tributary, fed by a spring. Lake Rupa, at 600 m a.s.l., is the smallest of the Pokhara lakes. It covers 135 ha and has a maximum depth of 6 m (Rai et al., 1995). It receives water of Talhesi stream.
In western Nepal Lake Rara (2900 m a.s.l.) is situated about 30 km north-west of Jumla. It receives a number of streams, and its outflow is Khater Khola, which eventually joins the River Karnali. Lake Syarpu (1372 m a.s.l.), an oligotrophic lake, covers about 75 ha and receives water from Khare Khola (Pradhan, 1982).
The largest Nepal reservoirs, Hanumannayar and Gandak, are situated on the border with India. 1 The only information available for reservoirs is that for Indrasarobar Reservoir on the River Kulekhani. This small reservoir is situated at 1430 m a.s.l. in the mid-hill region of Nepal, has a catchment area of 126 km2 and when full, it is about 7 km long, 380 m wide, covers 220 ha, and has a maximum depth of 105 m. The reservoir is located in a valley with very steep slopes. It is usually full during winter from November to December. From December to May the discharge of the Kulekhani River is a miniscule 1.2 m3/s. The rainy season usually begins in June and lasts until October. The river flow rate reaches a peak of 10-11 m3/s in July and August (Swar, personal communication). Other small reservoirs like Trisuli and Sun Kosi are not utilised for fishery, due to either heavy siltation (Trisuli) or a high rate of water flow through the reservoir (Sun Kosi).
Among the total of 186 fish species, 59 endemic and two exotic have been considered as coldwater fish (Table 3). Most of them are fished for subsistence and for sport. Most of them inhabit the streams and rivers of mid-hill valleys. The most important indigenous coldwater fish species are Neolissocheilus hexagonolepis, Schizothoraichthys spp,
Schizothorax spp and Tor spp, but many other coldwater fish species are fished for subsistence, some of the species also having value as sport fish.
2.1 Zoogeographical background
The subfamily Schizothoracinae, which includes snow trout (Schizothorax) of the family Cyprinidae, is present in the Himalayan and sub-Himalayan regions of the Indian subcontinent, Afghanistan, Central Asia, Kazakhstan, China and Myanmar. In India, snow trout is present in cold waters in Jammu, Kashmir, extending to Nainital (Himachal Pradesh). Menon (1971) reported the species S. kumaonensis from Nainital. Jhingran (1975) reported snow trout from Assam and eastern Himalayas through Bhutan and Sikkim at an altitude of 1180 m to 3000 m. In Pakistan schizothoracines are common fish in the mountainous north. In Nepal, this fish has been reported from rivers and lakes at an altitude from 784 m to 3323 m (Shrestha, J., 1981). Some high altitude lakes in Nepal are inhabited only by snow trout (Ferro, 1978; Pradhan,1982). Snow trout prefers rapids and pools of large torrential streams fed by snow-melt with water temperature from 8oC to 22oC (Sharma, 1989), but they are also known to inhabit lakes (Pradhan, 1982). There are 28 species of snow trout in the Himalayan and sub-Himalayan regions including Tibet, China and Pakistan (Sharma,1989). In Nepal there are 9 species, six species under the genus Schizothorax, and three species under the genus Schizothoraichthys (Table 3). Among the nine species, three species of Schizothorax, i.e. S. macrophthalmus, S. nepalensis and S. raraensis have been recently described from Lake Rara (2990 m a.s.l., Fig. 2) in north-western Nepal (Terashima,1984).
An as yet undescribed species of Schizothorax has been recorded from Lake Syarpu (1372 m a.s.l.), a mid-hill lake in Rukum district. S plagiostomus is a common species with a wide range of distribution from 742 m (Pokhara lakes) to 3049 m (Uttar Ganga, Dhorpatan). S. richardsonii is found in rivers between 1380 m and 2180 m. Schizothoraichthys inhabits mountain rivers from 1380 m up, with S. esocinus being reported from the Langtang River (3323 m). Jhingran (1975) has given a similar range of altitude from 1180 m to 3000 m for these species. S. richardsonii is found in Indrasarobar Reservoir on the Kulekhani River in Central Nepal (Pradhan and Swar, 1988) but the fish has declined in catches from 2% to 0.98% (Rai, 1990). Fig.3 shows the distribution of snow trout in rivers and lakes of Nepal.
Neolissocheilus hexagonolepis, commonly known as copper mahseer, is an important sport fish. In India this fish is known from northern Bengal under its Nepalese name `katli', and the fish is also present in Assam and Myanmar (Jhingran, 1982), and in the River Cauvery in Tamil Nadu (Chacko et al., 1954; Alikuhni, 1957). It is known from Bangladesh, Pakistan, Thailand, Vietnam and China (Jayaram, 1981). N. hexagonolepis is abundant in most of the big rivers, lakes and reservoirs of Nepal from 250 m to 1500 m altitude, having a preference for water temperature 10o - 30oC (Raj and Swar, 1989). This species was also found in the River Narayani, Chitwan, from 50 m to 300 m, near Nepal's southern border (Edds, 1986). N. hexagonolepis is also reported from Tadi, Trisuli, Kali Gandaki drainage at elevations of up to 1440 m, from the Kosi tributaries - mainly from Sun Kosi, Indravati, Tamar and Arun rivers up to 1220 m, and from the River Bagmati up to 1350 m.
N. hexagonolepis is the dominant fish species in Indrasarobar Reservoir, where in 1990 it represented 77.2% of the catch (Rai, 1990). It is found in lakes of the Pokhara valley (Shrestha, J., 1981; Ferro and Badagami, 1980; Ferro, 1980). Fig.3 shows the distribution of N. hexagonolepis in Nepal.
Tor (mahseer) is the most important sport fish of India, Pakistan and Nepal. It is also reported from Bangladesh, Myanmar, Thailand and China (Jayaram, 1981). MacDonald (1948) gave a very good account of its behaviour and of fishing for mahseer in India and Myanmar. From the seven species of Tor (T. putitora, T. tor, T. mosal, T. khudree, T. mussulah, T. neilli and T. progenecius), only T. tor and T. putitora are reported from Nepal (Shrestha, J., 1981). These have a wide distribution in Himalayan rivers from 135 m to
1650 m altitude. Both species inhabit the snowmelt-fed rivers Kosi, Sun Kosi, Tamar and Arun rivers of the Kosi drainage, and Bheri, Sakayel and Karnali of the Karnali drainage. They are also found in the Kali Gandaki and Nayarani from 50 m to 300 m (Edds, 1986) in the Gandaki drainage, as well as in the Tadi and Trisuli. Both Tor species are also present in the Pokhara Valley lakes. Tor putitora reaches up to 2.75 m in length in India (Jhingran, 1982), however the largest size recorded from Nepal for this species is 1.8 m and for T. tor 1.2 m (reported by fishermen). Fig. 3 gives the distribution of Tor in lakes and rivers of Nepal.
3.1 River fish
The main habitat of coldwater fish is the snowmelt-fed rivers. For the distribution of important coldwater species in the major rivers and lakes see Fig. 3.
The Kosi River in the eastern part of Nepal has 33 fish species. For the Bagmati River 22 species are listed as important coldwater fish (Table 3). The following zoning for the Bagmati River is based on the presence of the dominant fish species.
Snow trout zone (1875 m - 3125 m)
It is characterised by fast flowing cold snow-fed water dominated by Schizothorax plagiostomus and S. spp.
Stone carp zone (1250 m - 1875 m)
Stone carp (Psilorhynchus pseudecheneis), stone roller (Garra gotyla), loach (Noemacheilus spp) and sucker catfish (Glyptothorax spp) dominate the fast flowing waters in this zone.
Hill barbel zone (625 m - 1250 m)
This zone, with a fairly slow water current, is dominated by mahseer (Tor tor, T. putitora) and katle (Neolissocheilus hexagonolepis).
The River Gandaki system drains the central part of Nepal, and forms the deepest gorge in the world, as it flows through the Himalayas on its way from its headwaters on the Tibetan Plateau to lowlands, where it merges with the Ganges (Edds,1989). Thirty-five cold water species have been identified from the River Kali Gandaki alone (Table 3). Edds (1989) gives the following species zonation for the Kali Gandaki/Narayani rivers:
Schizothorax richardsonii zone (850 m - 2810 m)
This stretch of the river includes both mountain and Trans-Himalayan regions.
Schizothorax progastus zone (300 m - 850 m)
In this high hill region S. richardsonii is gradually replaced by S. progastus.
Barilius zone (50 m - 300 m)
The low hill region is named for the presence of its most common fish Barilius vagra.
The other rivers of the Gandaki system such as Seti, Madi, Marsyandi and Trisuli are important from the cold water fisheries point of view. The important fish species in these rivers are Tor putitora, T. tor, Neolissocheilus hexagonolepis, Semiplotus semiplotus, Garra annandalei, G. gotyla, Glyptothorax pectinopterus and Channa gachua.
The River Karnali arises on the Tibetan Plateau and enters Nepal, to become the major river system in Western Nepal. Menon (1954) recorded Noemacheilus spp as the dominant genus in this river, and Jha and Shrestha (1986) found S. plagiostomus in the upper reaches of this river.
3.2 Capture fishery
In Nepal capture fishery is widely scattered throughout the country and is not well organised. Fishermen, dispersed along water bodies, such as rivers and lakes, use their traditional gears predominantly for their own and their families' benefit. To date no reliable statistics are available on the number of fishermen and their families involved in subsistence fishing. In 1980 the estimate was that over 20,000 people were involved in capture fishery in Nepal (Swar, 1980). In 1991, the Fisheries Development Division estimated that more than 13,000 families were involved directly in fishing for their livelihood in addition to 9000 part-time families (Rajbanshi, 1995). Capture fishery is therefore only an incidental activity for most people living in the hills and mountains of Nepal. Subsistence fishery and sport fishery are practised at different levels of intensity on different rivers. While this may prevent the over-exploitation of some rivers, other river fish stocks may be under intensive fishing pressure. Since almost all captured fish are consumed immediately around the catch site, collection of statistical information on cold water fish production in streams and rivers is most difficult. Lately, fish stocks in some rivers have been threatened both by natural calamities and by human impact on fish habitats.
3.3 Lake and reservoir fishery
Several temperate and subtropical lakes and reservoirs provide habitats for a wide range of cold water fishes (Table 3). The best information available at present on fish and fisheries is that on lakes of the Pokhara Valley and for Indrasarobar Reservoir. Seventeen fish species out of the total of 28 inhabiting Pokhara lakes are cold water species (Ferro, 1980; Ferro and Badagami, 1979; Shrestha, J., 1981; Table 3). Studies of the larger lakes in the Pokhara Valley showed that lakes Phewa, Begnas and Rupa are productive and can support an annual fish harvest of 150 t with proper management (UNDP et al., 1985). At present, the lakes have cage culture of exotic carps.
Fish stocks in Indrasarobar Reservoir have been studied for a number of years (Pradhan and Swar, 1988). The reservoir has three indigenous fish species (N. hexagonolepis, Puntius chilinoides and S. richardsonii). Chinese carps have been grown in cages.
Among the 59 indigenous cold water fish species of Nepal, Neolissocheilus hexagonolepis, Schizothoraichthys spp, Schizothorax spp and Tor spp are the most important fish from the economic and sport fishery point of view. These are also an excellent food fish.
Neolissocheilus hexagonolepis (katle)
Katle is an important food and sport fish of Nepal. The usual size of fish is 0.6 to 0.8 kg, with the largest specimen in Indrasarobar Reservoir reaching 2.9 kg (Rai and Swar, 1989). In Lake Phewa the largest males and females reach 27 cm and 29 cm respectively. Katle feeds mainly on filamentous green algae, the lesser food components being chironomid larvae, crustaceans and water beetles (Ferro and Badagami, 1980). The fish mature when 3 years old or older (Rajbanshi,1982; Rai and Swar, 1989). In Pokhara lakes males mature when 16 cm long, females at 22.5 cm (Ferro and Badagami, 1980). The breeding season in Nepal is August-September (Rai, 1978). Jhingran (1975) reported for India a breeding season from May/June to August/September. In September/October the fish start their upstream migration and spawning takes place on stones and gravel at water temperatures of 18o-23oC (Rai and Swar, 1989). The eggs are sticky and attach themselves to plants and rocks.
A few experiments on artificial breeding of katle were conducted by Rai (1978, 1990a) and Shrestha, T.K. (1979). Stripping, with or without hormone injections, resulted in hatching success of 58 to 75% at a water temperature of 18o-23oC, pH of 6.8-7.7, and dissolved oxygen concentrations of 5.1-11 mg l-1. After yolk sac absorption eight-day-old hatchlings were fed egg yolk for a week and transferred to floating cages in Indrasarobar Reservoir (Rai,1990a). There they were fed a diet with three different protein levels (40%, 30%, 20%), or given no artificial feed. The highest survival rates (96% and 95% respectively, 6 months after their release in cages) were achieved with diets of 40% and 30% protein content. Without supplementary feed the survival rate was 60%, and the growth rate was slower (total length 4.0 cm, weight 0.65 g) than that of fish fed on a high protein diet (4.7-4.8 cm, 1.03-1.08 g). The reservoir water had a temperature of 18.1o-24.0oC, dissolved oxygen concentration of 6.6-10.9 mg l-1, pH of 8.0-8.3, alkalinity of 65.0-90.0 mg l-1, water transparency of 100-290 cm, phytoplankton counts per litre of 571,200-2,162,400, and zooplankton counts of 17-137 per litre (Rai, 1990).
Schizothoraichthys and Schizothorax
Snow trouts are locally known as asla and there are two genera found in Nepal. Snow trout with a pointed snout represents the genus Schizothoraichthys and is known as `chuchche asla'. Snow trout with a blunt snout belongs to the genus Schizothorax Heckel and is known locally as `buchche asla'. This paper follows the classification of snow trout according to Mishra (1959). Schizothorax molesworthii and S. progastus are regarded as the most delicious fish of Nepal and are known to be a good sport fish as well. Fish up to 2.5 kg have been reported from the Trisuli and San Kosi rivers (Sharma,1989). Masuda (1979) reported that S. plagiostomus reaches up to 22 cm (226.2 g) and S. progastus 25.7 cm (362.7 g) in the fourth year. Terashima (1984) reported a maximum size of 13.8 cm standard length (S.L.) for male and 15.6 cm S.L. for females of S. macrophthalmus, and 24.8 cm for males and 54.0 cm for females of S. raraensis.
Nepalese snow trouts are largely herbivorous, but S. raraensis and S. macrophthalmus feed on insects and the latter species also on plankton. Artificial propagation of S. plagiostomus in the 1960s and 1970s was successful (Shrestha,T.K., 1978, 1979). Tests with supplementary diet consisting of egg yolk, buffalo liver, poultry feed, phytoplankton and insects, fed to hatchlings of 1.5 mm, resulted in a rapid growth to 32.6 mm in 240 days (Sharma, 1989). In spite of that, indigenous cold water fish of Nepal have a slow growth rate. For example, in four years snow trout in the Trisuli River reached only 220 mm S.L. (226.2 g) and Schizothoraichthys 257 mm SL (363.6 g) (Masuda 1979). This is slow when compared with the growth rate of trout: brown trout (Salmo trutta) reaching 430 mm in the fourth year (Masuda, 1979). Slow growth has been observed in cage culture of N. hexagonolepis (Rai, 1990).
Tor
Tor tor (sahar) and T. putitora (mahseer) are important food and sport fish of Nepal. They tolerate water temperature between 15oC and 30oC. In the Trisuli River specimens of up to 30 kg have been captured (Shrestha, T.K., 1979). Tor spp are omnivorous and Kaushal et al. (1980) reported that adults of T. putitora in Gobindsagar reservoir in India subsisted mainly on fish, supplemented by zooplankton, dipteran larvae and plant matter. Juveniles appeared to subsist mainly on plankton. Shrestha,T.K. (1979) reported that the mature Nepali mahseer fed mainly on gastropods, plant debris and algae. The fingerlings of this fish feed mainly on algae. Tor tor feeds on filamentous algae, chironomid larvae, water beetles and crustaceans, with fish bones also mentioned as food by Ferro and Badagami (1980). Tor exhibit sexual dimorphism, with tubercles present at the end of the snout in mature males (Shrestha,T.K., 1986). In Nepal, T. tor spawn from March to September (Swar, 1979), T. putitora from June to September (Shrestha, T.K., 1986). Both prefer gravel and stones as spawning substrate.
Artificial propagation of Tor tor, T. putitora, N. hexagonolepis and Schizothorax spp using stripping and injection with pituitary gland extract has been successful. T. putitora was reproduced under controlled conditions by stripping or pituitary gland injection. On the fish farm in Trisuli, where stripping was applied, Masuda and Bastola (1985) gave hatching time as 45-55 hours and the percentage of hatched eggs as 63.4%, at water temperature of 23.9o-29oC. For the same species in Lake Phewa, using an extract of pituitary gland for induced breeding, Shrestha, B.C. et al. (1990) mention hatching time of 64 hours and hatching efficiency of 97% at water temperature of 29-30oC. More work is needed to develop a standard technique for mass production of fry and fingerlings and to grow them in captivity. At present fingerlings are released into rivers and lakes although Tor tor has been experimentally stocked in cages in Indrasarobar reservoir.
In the early 1990s His Majesty's Government of Nepal with the grant aid assistance of Japan formulated a development plan for exploitation of natural water bodies. The main policies were the development of cage fish culture in lakes and reservoirs and the establishment of aquaculture technology for the indigenous riverine fish species. The Fisheries Development Section selected Pokhara for a development centre for cage culture, and Trisuli and Godawary for aquaculture technology for indigenous species of fish. The proposed project envisaged strengthening the above-mentioned fisheries development centres with the following objectives:
The Government has realised that the expansion of aquaculture is not possible without the use of cold waters and coldwater fish. The following steps have already been taken to develop coldwater fishery in Nepal:
Besides N. hexagonolepis, Schizothoraichthys spp, Schizothorax spp and Tor spp, there are many other cold water species which display promising potential from a fisheries point of view. Most of these fish are valued by the local people for their size and food value. However, little is known about their biology and behaviour.
Puntius (Barbus) chilinoides (karange) is found in Indrasarobar reservoir, Pokhara lakes, Trisuli, Sun Kosi and Bagmati rivers. It reaches a size of 22 cm and it is a sport fish. It is the second major species in Indrasarobar reservoir (Rai, 1990) with a spawning season from March to June.
Labeo angra (thed or thaind) is an important food and sport fish. It is captured by `looping' in the Trisuli and it inhabits the Kosi and Karnali rivers to an altitude of 1650 m (Shrestha, J., 1981).
Labeo dero (gurdi) is an important food as well as sport fish which reaches 35.0 cm length and weighs up to 4 kg in the Tadi river at an altitude of 1500 m (Shrestha, J., 1981). The fish is herbivorous (Masuda and Karki, 1980) and matures even when kept in ponds.
Barilius spp (fageta) has several species in Nepal, such as N. bendelisis, B. vagra, B. barila and B. bola. They inhabit cold waters up to 1650 m altitude (Shrestha, J., 1981). They reach a size of only 20 cm but are favoured for their tasty flesh.
Chagunius chagunio (patharchatti, kubre) is a table fish of up to 25 cm length. It inhabits torrential rivers such as the Trisuli and Tadi and it is also present in Lake Phewa at an altitude of 742 m (Shrestha, J., 1981).
Clupisoma garua (jalkapur) is a very tasty fish which reaches a length of 30 cm. It is present in rivers Trisuli, Narayani and Karnali up to 1440 m (Shrestha, J., 1981).
Bagarius bagarius (gonch) is a migratory fish which starts upstream migration in early May to reach by June headwaters of rivers and streams up to the 1424 m altitude. The largest specimen of 180 cm is known from the Sun Kosi (Shrestha, J., 1979).
There are other typical hill stream fish none of which have any economic importance but they are appreciated as subsistence food by the local people. The hillstream fish are all adapted to the fast flowing waters. Among them belong ten species of Glyptothorax which have been found up to 1650 m altitude. In the Sawa tributary of the River Arun (1067 m) in the Kishi drainage Glyptothorax cavia reaches 18 cm length (Shrestha, J., 1981). There are also four species of Garra in Nepal, which inhabit torrential streams and rivers up to 1650 m altitude (Rajbanshi, 1982). Their total length ranges from 15 cm to 17 cm.
Eleven exotic fish species of food and sport value have been introduced in Nepal. These include the coldwater fish rainbow trout (Oncorhynchus mykiss), introduced in 1968 and 1971 from India, and in 1988 from Japan. Brown trout was introduced in 1971 from England and Japan. Other introduced species tolerating cooler waters are: common carp, silver carp, grass carp and bighead carp, which have been cultured since 1955/56. More recently Carassius auratus was also introduced (Rajbanshi, 1995). In warm water aquaculture of Nepal Puntius gonionotus and red tilapia are propagated (Rajbanshi, 1995), and two tilapias, Oreochromis niloticus and O. mossambicus, immigrated from India during floods. Tilapias are now produced in private sector aquaculture in the Terai.
The first rainbow trout fingerlings from Kashmir, India, and fertilised eggs (eye stage) from the United Kingdom were reared in the Godawary Fishery Development Centre, Kathmandu. The first trout hatchery was established in Nuwakot on the bank of the River Trisuli. Its objective was to propagate, rear and release the trout in suitable hill streams to establish sport fishery for tourist development. These trout were later transferred to the Trisuli trout hatchery but the trout did not survive. Realising the importance of trout for cold waters of Nepal, 50,000 eye stage eggs of Oncorhynchus mykiss were again imported from Japan in November/December 1988 and incubated in the Godawary Fisheries Development Centre where about 80% of eggs hatched. The hatchlings were reared to the fingerling stage and half of the fingerlings were sent to the Trisuli Fishery Development Centre. This Centre has developed pelleted feed for trout. The Centre also succeeded in breeding the trout without hormonal injection. A similar success has been achieved in the Godawary Fishery Development Centre, where, however, the mortality of hatchlings has been higher than in the Trisuli Centre.
A programme for research on the growth rate of trout, local feed effectiveness and spawning behaviour of trout in Nepalese waters, and on interactions between native fish and exotic species has been formulated and is being implemented by the two government Centres in Trisuli and Godawary. The present trout production is about 5 t/year (Joshi and Westlund Lofvall, 1996). A high survival rate has been achieved throughout the experimental period at the Centre in Trisuli. The study, carried out in 1994/95, showed that with the application of the existing technology a production of 100-150 t/ha/year could be achieved.
In Nepal fish come from pond and cage culture, as well as from capture fisheries. The total fish production increased from 3530 t in 1981-82 to 21.879 t in 1995-96. During the same period fish production from capture fishery increased from 2780 t to 11,230 t (Table 4). Much of this increase came from the irrigated paddy fields, wetlands, lakes and reservoirs, while capture from rivers has stagnated since 1986/87. Pond production in warm waters has doubled over the period 1986/87 to 1995/96. Between 1981/82 and 1995/96 the per capita fish production increased from 0.33 kg to 1.05 kg.
The future of the coldwater fishery will require more attention to be paid on the one hand to maintaining good conditions for fish in wild waters, and on the other hand to enhancing cold water fish stocks through regular releases in selected rivers, reservoirs and lakes of hatchery-produced stocking material. A hatchery has been proposed for the Kali Gandaki `A' hydroelectric project. It is expected that this hatchery will produce mahseer, katle, snow trout (S. richardsonii), jalkapoor and some other indigenous fish species for stocking into the reservoir and its tail waters (Swar and Shrestha, J., 1996).
Capture fishery is using both conventional and non-conventional fishing methods. Conventional methods cover the use of nets, bamboo traps, rod and line, and looping. Non-conventional methods are the use of explosives, and poisoning.
Nets: Cast net and gill net are commonly used, as well as dip net (thakauli) and scoop net (ghorlang). Thakauli net is shaped like a bag with an elliptical mouth narrowing posteriorly. The mouth has a bamboo rim and the mesh size of the net is 10 mm. The net is used in shallow waters. Fishermen fish by dipping the net and lifting it out. The net catches small-sized fish. Ghorlang is a scoop net with a wooden handle about 1.5 m long. The handle is fixed to a circular wooden rim made up of two pieces. The first forked piece is joined with the handle, and the other is curved or semicircular. A conical net is fixed on the wooden rim.
Ghorlang can be used in fast flowing water even in rainy season. It is operated by one person by holding the handle, dipping the net in water and rapidly lifting it out.
Bamboo traps: A rectangular bamboo trap (funga) about 1.2 m long and 0.45 m wide is used for collecting small fish. The trap is left in a stream in a fixed position. Several elongated conical bamboo traps of approximately 1.5 m in length and 0.25 m in circumference are used in the hills of Nepal. Their size varies from place to place. They are used in very fast waters.
Rod and line: The hook for the line is usually made from the metal of an umbrella. The hooks are attached to the line. Bait is small pieces of fish, earthworms, bread or flour or fish fry. A single man may operate several rods at the same time.
Fish spearing: Atkinson (1974) described the spearing of the fish at night with the help of torch light. Fish spearing is done in Lake Rara. In Sun Kosi and Trisuli rivers instead of a spear, a kukri knife is used (Shrestha, J., 1994). The fishing is done at night, with 4-6 persons usually involved. Torch light or a lantern are used to attract the fish to light. The fish (N. hexagonolepis, Schizothorax spp, Barilius barana, etc.) which come to the light are hit on their head with the knife.
Looping: Looping, locally called `paso', is practised in the Trisuli (Rajbanshi,1976) and Sun Kosi rivers. The loop is made from a nylon thread. A single line may support 3-5 loops. The size of loop regulates the size of catch. A coloured lead weight functions as bait. Live bait such as fish, shrimp, earthworms, stonefly and mayfly larvae are also used in looping in the Trisuli and Sun Kosi. When a fish detects the slowly moving coloured lead it mistakes it for insect larva, approaches the lead and enters into the loop where it gets stuck by its dorsal and pectoral fins. Fish are looped in the afternoon and evening, when fish up to 6 kg may be captured. Paso is used from September to April, when the stream water is clear and cold and the fish start their upstream migration. This method captures Schizothorax (asla), Labeo angra (thaind) and some other fish.
Use of explosives: Before using explosives fishermen throw rice or oil cakes into the pool to attract and concentrate the fish. They wrap the explosive in thick cloth, ignite it and throw it in the pool. The killed or stunned fish are then collected by scoop net. This method catches predominantly N. hexagonolepis, Tor, Garra, Psilorhynchus, Glyptothorax and Noemacheilus.
Poisoning: Leaves of Sapium insigne, Agave americana are crushed and thrown in the water. Bark and roots of Dalbergia stipulacea are also used for poisoning fish. The crushed leaves and fruits of Adhatoda vasica and Randia dumentorum are commonly used in ditches for catching fish. Pithecallobium bigeminum is also used for fish catching. These are common plants in the Terai. Edgeworthia gardneria, Polygonum flacidum, P. hydropiper, Ficus pumila and Acacia pennata are also used as fish poison. More recently, pesticides such as Aldrin, Thiodine, BHC, Malathion, and DDT have also been used.
The usual fish preservation is by smoking or sun-drying. There is no fish processing factory in Nepal. Fish are also sold fresh in markets where they are transported on ice. The ratio of fish to ice is 1:1 in summer and 3:1 in winter. There is no fish cold storage yet in Nepal and ice factories are only in towns and they do not produce enough to satisfy the demand for ice. Freezing of fish is done only in large cities where shopkeepers use a deep freeze for long-term storage. During 1983/84 84% of businessmen who responded to a survey (DFAMS, 1985) used ice blocks to keep their fish in fresh condition, but only 9% of the respondents had a deep freeze to store fish and 6% used a nearby cold storage to keep fish in fresh condition.
Smoking: The problem of fish preservation is acute in hilly regions of Nepal where there is no ice and poor marketing potential. The unsold fish are smoked. A crude method of smoking is keeping the fish above the kitchen oven. Wet leaves and wet logs are used to fire the oven to produce smoke which acts as a preservative. Three to four days or even longer are needed to complete the preservation. Larger fish are cut into pieces and inserted in bamboo sticks and placed above the fire. Small ones are smoked whole. The following fish are smoked: N. hexagonolepis, Chagunius chagunio, Schizothorax, Barilius, Semiplotus semiplotus, Garra, Channa, Glyptothorax and Pseudecheneis.
Sun-drying: Small fish such as Puntius, Oxygaster, Anabas, Nandus and Channa are dried in the sun, especially in the Terai. These dried fish, locally known as sidra, have a nice taste and are used for pickles. The fresh fish are spread on mats for sun-drying for 3 to 4 days depending upon the weather condition and size of the fish.
Information on fish demand and consumption in Nepal is very limited. Fish is generally accepted and liked by all non-vegetarians in Kathmandu. The per capita intake of fish is a low 1.05 kg/person/year, which, however, does not include imported fish. In Kathmandu Valley the per capita supply is approximately 2 kg/person/year. As up to 75% of the fish sold in the Kathmandu market come from India they are the lowland, warmwater fish species. The majority of marketed fish are the major Indian carps rohu (50%) and catla (20%), and the Chinese silver carp (15%); the rest are other fish species (Dahal, 1998). Hill stream fish such as Tor, Neolissocheilus, Schizothorax, Glyptothorax and Garra are sold in smoked form in Kathmandu market, where they are brought from adjacent areas such as Trisuli, Dolalghat and Panauti (Shrestha, J., 1994).
Generally, fishermen and fish producers sell their product directly through retailers/wholesalers and middlemen. In selling their fish farmers have three options, i.e. selling to the consumer at the local market, selling to an Indian agent, and selling to wholesaler through contractors. About 28% of the total catch is consumed or given away by the farmer, and 30% is sold directly to consumers (DFAMS, 1985). About 42% of the total catch/harvest is purchased by wholesalers from contractors and distributed to retailers in the major urban centres, such as Kathmandu and the adjacent border area of Nepal. Each wholesaler sells on average 100 kg fish/working day or approximately 30 t/year. These fish are packed in baskets with ice and transported by local bus or truck.
Retail market traders purchase fish from wholesalers. A typical retail market is an open front 4 x 3m shop, or else fish are kept in baskets in vegetable markets or on sides of footpaths. Frozen fish is not preferred by consumers due to its relatively high cost. However, the demand for fresh fish is high. Frozen fish is sold mainly to foreigners in Kathmandu. In 1988, about 150 t of frozen fish was sold in Kathmandu at the cost of Rs 60-80 per kg.
The total demand for fish in Kathmandu was 63 t per month in 1963-84 (DFAMS, 1985). In 1988-89 the total demand in Kathmandu was approximately 89 t/month (Chaudhary, 1989). The cost of fish is high in Kathmandu in comparison to the Terai region due to high transport charges, storage costs, taxes, rents and wages. The average retail price per kg of fish at Kathmandu market was NRs 15.7 in 1977 and NRs 28.9 in 1983, which was 84 % higher in comparison to the price in 1977 (DFAMS, 1985). In 1991 the retail price in Kathmandu was NRs 70-80/kg (US1 = NRs 32.40).
There is a great demand for cold water fish whether fresh or smoked, but their supply is very limited due to the poor road system, or no roads at all. Also, the small catch, after local consumption, does not leave many fish for marketing in more distant places.
Poor quality of fish is a major problem. There is inadequate supply of ice, unreliable transport, and the hygienic conditions at markets are often poor. A study of the condition of fish in the Kathmandu market revealed that about 90% of consumers reported that the fish they purchased was in poor condition (Chaudhary, 1989).
Although cold waterfish are very popular for their taste and as sport fish, little has been done to enhance the stocks through better management. The main constraints to the wider use of the local coldwater fish are:
There is at present no management programme for the capture fisheries sector in Nepal. Without a management programme and policies to control the fishery resource, many problems facing coldwater fish stocks and fisheries cannot be resolved. The following problems need to be addressed:
12. CONCLUSIONS
The capture fishery sector including coldwater fishery has been given lesser priority by the government fisheries administration. This has contributed to a gradual decline in fish stocks in some areas. There has been slow progress in expanding aquaculture of coldwater fish species, and very little has been done in enhancing the river and lake fish stocks through stocking. Improved education to raise awareness in the local people of the need to protect catchments to prevent further deterioration of fish habitats has also been wanting. The following recommendations should assist in improving the current situation in coldwater capture fisheries in Nepal.
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1 No information on their fish stocks and fisheries is available. Being located at low altitude, the reservoirs probably harbour warmwater fish, and their potential is probably reasonably high (Ed.).