Department of Fishery Hydrography, College of Fishery Sciences
G. B. Pant University of Ag. & Tech., Pantnagar-263145, Uttaranchal,
India
ABSTRACT
The newly created hill state, Uttaranchal, located in the Central Himalayan region of India, is endowed with vast natural freshwater resources. Tor putitora (golden mahseer) is one of the main game and food fish in the Central Himalayan region. However, the population of Tor putitora has greatly dwindled over the years, so much so that it constitutes only a negligible part of fishery in the majority of rivers and streams. The present study, carried out in six rivers of the west Uttaranchal, i.e. Garhwal region of Central Himalaya, has revealed that it contributes significantly only in one river, i.e. Nayar (32.8%). It constitutes about 9.7% of the total fish catch in the river Song, while in other rivers the percent population ranges between 0.8 and 3.1%. The catch size has also greatly decreased, ranging from 28.0 g and 13.5 cm to 1 650.0 g and 52.5 cm only. The average catch per unit effort of mahseer in the river Nayar was recorded as 67.92 g/man/hr with the minimum and maximum values being 25.0 and 875.5 g/man/hr. On the basis of ecodatabase, availability of the brooders, fry and fingerlings, only the river Nayar could be considered as a potential mahseer stream. The paper discusses the present status and prospects for the development of the fishery of golden mahseer in the Garhwal region of the Central Himalaya and the measures to be adopted for the rehabilitation of its stocks in suitable streams.
The abundant surface water resource in the Central Himalayan region of India provides a great opportunity for the development of fishery of the golden mahseer. These denizens of Himalayan waters are a source of recreation for people from India and abroad and also have great food potential for hill people. Therefore, the mahseer may play a great role in the socio-economic development of the hill region. However, due to unthoughtful exploitation by man, the stocks of mahseer have greatly dwindled in these waters.
Though mahseer has great game and food value, the various attributes of its fishery have not been investigated comprehensively, especially in the Central Himalayan waters (Mishra et al., 2000). Even the catch data from the major rivers are not available. Whatever studies have been done are sporadic and preliminary in nature, therefore the correct picture of mahseer fishery cannot be construed. The majority of the studies conducted until now are confined only to the biological aspects such as taxonomy, morphology, food and feeding, physiology, distribution, life history stages, length-weight relationships (Desai, 1972; Badola and Singh, 1980; Sen and Jayaram, 1982; Nautiyal and Lal, 1982, 1984 and 1984a, 1988).
The research work on the aquaculture feasibility, hatchery production of fish seed, development of suitable feeds, intensive culture in cages/raceways/running water systems is warranted for developing the technology package for the conservation, rehabilitation and propagation of mahseer in the Central Himalayan region.
The present paper deals with the above aspects for the development of fishery of golden mahseer in the Garhwal region of Central Himalaya.
The Garhwal Himalaya forms the western part of Central Himalaya. It is situated between the latitudes 29026' - 31028' N and longitude 770 49' - 800 6' E. The region has a total area of 30 090 km2. The fresh water resources in the Uttaranchal State include 2700 km of rivers and their tributaries, 31 lakes spread over an area of about 300 ha, and 6 reservoirs encompassing 18 931 ha. There are also 1 341 ponds covering an area of 628 ha. The majority of the water resources are located in the Garhwal region. The geographical and physical features of selected streams, including the place(s) and altitude of sampling points, of Garhwal Himalaya are given in Table 1.
Table 1
Geographical and physical features of the selected streams of Garhwal Himalaya
Stream |
Altitude (m) and the source |
Type |
Working place |
Altitude of working place |
Temperature range (°C) |
Tributary of the major river |
B hagirathi |
3 920 |
Snowfed |
Sirai to Old Tehri |
750 -640 |
10.2-23.5 |
Ganga |
Bhilangana |
3 560 |
Showfed |
Bhado Ki Magari to Old Tehri |
770-640 |
10.8-23.5 |
Bhagirathi |
Western Hiyunl |
2 250 |
Spring fed |
Nagani to Khadi |
1 000-950 |
13.5-27.0 |
Ganga |
Song |
- |
Spring fed |
Doiwala to Raiwala |
425-380 |
18.5-27.5 |
Ganga |
Khoh |
1 951 |
Spring fed |
Dogadda to Kotdwar |
615-375 |
16.0-26.5 |
Ramganga |
Nayar |
2 835 |
Spring fed |
Satpuli to Vyasghat |
760-442 |
14.0-26.0 |
Ganga |
The rivers Bhagirathi, Alaknanda, Ganga, Yamuna and Western Ramganga constitute the main drainage system in Garhwal region. Alaknanda is the largest river, covering a distance of about 240 km. Bhagirathi is second largest and takes its origin at Gaumukh Glacier near Tibet border at an altitude of 3 600 m. It slopes down to Gangotri and Uttarkashi and receives the Bhilangana River at Tehri (Fig. 1). At Deoprayag the Bhagirathi and Alaknanda confluence to form the holy river of India, the Ganga.
Fig. 1 - Drainage system of Garhwal Himalaya
The river Bhilangana, which arises from Khatling Glacier (3658 m), confluences with the Bhagirathi at Old Tehri, where Asia's biggest dam is under construction.
The Nayar river in the Garhwal Himalaya is a spring-fed stream with rocky/sandy basin. Nayar receives two tributaries, Eastern and Western, near Satpuli and joins the river Ganga at Vyasghat. The eastern and western tributaries of Nayar originate from northern and southern peaks of Doodhatauli hills. The Song is a right side tributary of river Ganga. This is a spring-fed river with sandy and rocky substratum. The Khoh River is also a spring-fed stream with rocky/sandy substratum; it is a tributary of the river Ramganga.
The river Hiyunl originates from Devidanda Hills and passes through Dhangoo block in Lansdown sub-division of Garhwal. It is also a tributary of the river Ganga.
In the present study 6 rivers were selected for the preparation of ecodatabase and evaluation of status of mahseer fishery. Among the selected rivers, four are spring-fed (Western Hiyunl, Song, Khoh and Nayar) while two are snow-fed (Bhagirathi and Bhilangana). The rivers are located between altitudes 425 and 1 000 m. The selection of study sites was based on habitat characteristics and potential for mahseer.
Fifteen sampling sites spread over six rivers were selected. The study was conducted during April 2000 to March 2001. Fish sampling was done monthly at all selected sites, up to a 1 km in each river, by use of cast net and gill net. The mesh size of cast net and gill net were 2.0-3.0 cm and 2.0-10.0 cm, respectively. The observations were made on fish species, percent population, proportion of mahseer in the total catch, average body weight and length and age of mahseer. The fish records from local fishermen were also regularly noted at each site.
The analysis of physical and chemical characteristics of water was done fortnightly at the sampling stations. The flow rate, average span and depth of the river were recorded using standard methods. Water temperature was recorded using mercury thermometer calibrated to 0.1°C. The pH and dissolved oxygen were analyzed using digital analyzers at the site. Free CO2, total alkalinity and silicate were estimated following standard methods (APHA, 1985). Length, weight and width of fish were measured using measuring scale and monopan balance. Age of mahseer was determined by counting the annual rings in scales.
4.1 Physico-chemical characteristics
To find out the suitability of the selected streams for mahseer, an ecodatabase was prepared. The data on various physical and chemical characteristics of water of various rivers are given in Table 2.
During the study period the average water temperature ranged from 9.0 to 27.8°C. The snow-fed river Bhagirathi had the lowest and spring-fed river Nayar had the highest temperature. Average water temperature fell below 6°C in the Bhagirathi River. Excepting Bhagirathi and Bhilangana, the average depth of the rivers was between 0.4 and 1.75 m. Bhilangana and Bhagirathi are deeper, with depth ranging between 1.0 and 8.0 m. Water current was faster in the snow-fed rivers Bhagirathi and Bhilangana, with maximum values of 1.6 to 2.0 m/s, than in the spring-fed rivers (0.5 to 0.7 m/s). The average width was highest in Bhilangana (17.1m) and Bhagirathi (21.0 m), while it varied between 6.8 and 12.9 m in the rivers Hiyunl, Song, Khoh and Nayar. The water of all rivers had almost similar average transparency (30.1-32.4 cm), but individual values reached up to 44 cm in the river Nayar during February. Rivers Nayar and Bhagirathi had highest concentrations of total dissolved solids (161.0-162.8 mg/L); relatively lower values were recorded in rivers Hiyunl, Song and Khoh (114.5 to 132.2 mg/L). Excepting Bhilangana, which had a mean pH value of 6.0, the water of other rivers was neutral to slightly alkaline (pH 7.0-7.5). The maximum pH (7.9) was recorded in the river Song during April. All rivers and streams had good concentrations of dissolved oxygen (range 6.0 to 12.0 mg/L). The maximum concentration was found in the river Bhagirathi during January and the minimum was recorded during July in the river Song. The free CO2 showed wide fluctuation in concentration from 0.0 to 8.0 mg/L, but its values ranged between 2 and 4 mg/L in most of the selected rivers during the study period. Higher concentrations occurred during the monsoon period. Marked differences existed in the total alkalinity concentrations. While the Song had an average value of 184.3 mg/L, the mean concentration in the Bhilangana was only 38.6 mg/L. In general, alkalinity is higher in spring-fed than snow-fed rivers. The silicate content was higher in snow-fed (0.5-0.6 mg/L) than in spring-fed rivers (0.1-0.4 mg/L).
4.2 Biological characteristics
The average periphyton (aufwuchs) densities ranged from 170 no/cm2 (Western Hiyunl) to 490 no/cm2 of substrate (Nayar). Hiyunl and Khoh had lower densities than other rivers (Table 3). Bhilangana and Bhagirathi both supported moderate densities of periphyton.
Table 2
Annual mean and range of water quality parameters in different rivers in Garhwal region
The data are averaged across the various sampling stations
Parameter |
River-Western Hiyunl |
River-Song |
River-Khoh |
River-Nayar |
River-Bhilangana |
River-Bhagirathi |
|
Water temperature |
Average |
20.6 |
22.3 |
22.0 |
20.1 |
17.8 |
16.9 |
|
Range |
13.0-26.9 |
15.0-27.0 |
13.4-27.8 |
10.0-26.4 |
9.5-25.5 |
9.0-25.5 |
Water depth |
Average |
0.79 |
0.83 |
0.61 |
0.84 |
2.02 |
4.48 |
|
Range |
0.45-1.3 |
0.35-1.75 |
0.4-0.85 |
0.7-1.2 |
1.0-2.8 |
2.0-8.0 |
River width |
Average |
8.6 |
11.85 |
6.88 |
12.97 |
17.1 |
21.0 |
|
Range |
6.0-11.2 |
7.5-14.5 |
4.4-9.6 |
7.0-18.5 |
12-22.6 |
12-290 |
Flow rate |
Average |
0.6 |
0.7 |
0.5 |
0.6 |
0.9 |
1.2 |
|
Range |
0.4-0.9 |
0.5-1.0 |
0.4-0.8 |
0.5-1.2 |
0.6-1.6 |
0.9-2.0 |
Transparency |
Average |
31.9 |
32.12 |
33.22 |
30.70 |
30.17 |
32.43 |
|
Range |
27.2-42.0 |
26.5-42.0 |
27.5-42.0 |
23-44 |
14.5-40.0 |
15.4-29.0 |
Total solids |
Average |
123.4 |
132.2 |
114.5 |
162.8 |
156.2 |
161. |
|
Range |
102-150 |
92.0-195.0 |
92.2-128 |
110-210 |
136.8-165.61 |
145-171 |
PH |
Average |
7.0 |
7.5 |
7.0 |
7.0 |
6. |
7.0 |
|
Range |
6.8-7.2 |
7.4-7.9 |
6.9-7.2 |
6.8-7.2 |
6.6-7.0 |
6.8-7.0 |
DO |
Average |
8.0 |
7.8 |
7.6 |
8.1 |
8.0 |
7.9 |
|
Range |
7.4-8.8 |
7.2-9.0 |
6.8-8.2 |
6.0-8.8 |
6.6-8.8 |
7.2-9.2 |
Free CO2 |
Average |
1.74 |
1.66 |
2.2 |
2.3 |
2.7 |
2.3 1 |
|
Range |
0-8.0 |
0-8.0 |
0-4.0 |
0-6.0 |
0-6.0 |
0-6.0 |
Total alkalinity |
Average |
122.6 |
184.3 |
89.4 |
80.9 |
58.6 |
73.1 |
|
Range |
106-142 |
150-210 |
72-106 |
56-112 |
44-84 |
56-90 |
Silicate |
Average |
0.1 |
0.3 |
0.3 |
0.4 |
0.5 |
0.6 |
|
Range |
0.34-0.22 |
0.05-0.88 |
0.1-0.66 |
0.22-0.70 |
0.45-0.65 |
0.60-0.71 |
Table 3
Periphyton (aufwuchs) densities in selected rivers of Garhwal Himalaya
The data are averaged across all sampling stations in the rivers
Density (no/cm2) |
River- Western Hiyunl |
River- Song |
River- Khoh |
River- Nayar |
River- Bhilangana |
River- Bhagirathi |
Average |
170 |
247 |
188 |
490 |
305 |
370 |
Range |
11-542 |
6-1 183 |
40-701 |
40-1 208 |
12-1 329 |
14-655 |
In terms of group composition, Chlorophyceae (green algae) and diatoms were the sole components of periphyton (Fig. 2). Chlorophyceae comprised 24.4 to 47.9%, whereas diatoms constituted 52.1 to 75.6% of the total annual population. Green algae were most dominant in Khoh; the maximum population of diatoms was recorded in river Nayar (75.6%).
Fig. 2 - Mean percent composition of periphyton groups in different rivers of Garhwal Himalaya
The zooplankton population ranged between 58 and 77 ind./L (Table 4). The lowest and highest population was recorded in the rivers Bhilangana and Song, respectively.
Table 4
Mean standing crop of zooplankton in different rivers of Garhwal Himalaya
The data are averaged across all sampling stations
Standing crops (no/L) |
River- Western Hiyunl |
River - Song |
River - Khoh |
River- Nayar |
River- Bhilangana |
River- Bhagirathi |
Average |
59 |
77 |
75 |
67 |
58 |
77 |
Range |
10-208 |
1-288 |
19-182 |
9-198 |
16-125 |
12-166 |
Protozoans, rotifers, copepods and cladocerans represented the zooplankton community. Protozoans comprised 24.0 to 44.7% of the total zooplankton (Fig. 3). The percent population of the other zooplankton varied from 59.1 to 76.0%. Annually, the population was apportioned between protozoans (35.6%) and other zooplankters (64.4%).
Fig. 3 - Mean percent composition of zooplankton groups in rivers of Garhwal Himalaya
The benthic fauna in the rivers comprised of Ephemeroptera, Odonata, Plecoptera, Hemiptera and Diptera. The annual range of the benthic fauna varied most in the Nayar River (Table 5). The Nayar River was the richest while the Bhagirathi had the lowest population. In general, spring- fed streams had more benthic fauna than snow-fed rivers.
Table 5
Mean abundance of macrobenthic fauna in different rivers of Garhwal Himalaya
The data are averaged across all sampling stations
Mean abundance (no/m2) |
River- Western Hiyunl |
River - Song |
River - Khoh |
River- Nayar |
River - Bhilangana |
River- Bhagirathi |
Average |
920 |
1411 |
1188 |
1624 |
698 |
429 |
Range |
196-2 003 |
285-3 126 |
290-3 116 |
125-34 15 |
245-1 341 |
111-1 200 |
The ephemeropterans were most abundant with annual mean percent population in different rivers varying between 32.4 and 47.2. Again, the lowest and highest values were recorded in the rivers Bhagirathi and Nayar, respectively (Fig. 4).
Fig. 4. Mean percent composition of macrobenthic groups in different rivers of Garhwal Himalaya
4.3 Ichthyofauna
The fish fauna of the rivers of Gahrwal Himalaya is represented by Schizothorax spp., Tor putitora, Labeo dero, Labeo dyocheilus, Garra gotyla, Crossocheilus latius, Barilius bendelisis, Glyptothorax pectinopterum, Mastacembelus armatus and Botia spp (Table 6).
Table 6
Fish species found in rivers of Garhwal Himalaya
River/Stream |
Fish Species |
Western Hiyunl |
Tor putitora, Schizothorax spp., Labeo dero, Crossocheilus latius, Barilius bendelisis, Botia spp,. Glyptothorax pectinopterum |
Song |
Tor spp,. Mastacembelus armatus, Labeo dyocheilus, Labeo dero, Schizothorax spp,. Barilius bendelisis |
Khoh |
Schizothorax spp,. Tor putitora, Barilius bendelisis, Garra gotyla |
Nayar |
Tor putitora, Barilius bendelisis, Schizothorax spp,. Mastacembelus armatus, Labeo dero, Labeo dyocheilus, Garra gotyla |
Bhilangana |
Schizothorax spp,. Tor putitora, Garra gotyla |
Bhagirathi |
Schizothorax spp., T or putitora, Garra gotyla |
Schizothorax spp. are most important in the rivers, with total contribution of 52.6% on the basis of the mean values of the fish catch from 15 sampling stations on 6 representative rivers/streams (Fig. 5).
Fig. 5 - Percent composition of fish in the Central Himalayan rivers
The mean contribution of Tor putitora comes to only 11.8%. After Schizothorax, the major fishery is comprised of species of subsistence values, viz. Barilius spp., G. gotyla, Labeo spp.
The catch data in terms of numbers and percentage of Tor putitora, Schizothorax spp. and other fish are given in Table 7. Tor putitora, with percent contribution of 32.8% of the total fish population, is the most dominant fish in the river Nayar; Song, with 9.7% population of T. putitora, ranks second.
Table 7
Fish catch statistics at various sampling stations in different rivers of Garhwal region
Groups |
Western Hiyunl |
Song |
Khoh |
Nayar |
Bhilangana |
Bhagirathi |
Tor putitora |
||||||
Total No. |
1.67 |
30.67 |
1.5 |
119.33 |
5.5 |
4.5 |
Percentage |
0.8 |
9.7 |
0.9 |
32.8 |
3.1 |
2.6 |
Schizothorax spp |
||||||
Total No. |
84.33 |
80.33 |
81.5 |
181.33 |
141.5 |
156.5 |
Percentage |
48.1 |
26.4 |
25.4 |
51.5 |
84.2 |
90.6 |
Miscellaneous |
||||||
Total No. |
87.67 |
193.67 |
120.5 |
55.33 |
21 |
12 |
Percentage |
51.0 |
63.8 |
73.6 |
15.5 |
12.6 |
6.7 |
The data are averaged across all the sampling stations
The percentage catch of T. putitora in the selected rivers is shown in Fig. 6. The percent catch is 0.0-6.0% in the rivers Bhilangana and Bhagirathi, while in the river Nayar it comes to 2 to 60%, with a maximum being recorded during May, September and October.
Fig. 6 - Percentage catch of golden mahseer in selected rivers of Garhwal Himalaya
In the river Song, the maximum population (20%) was also recorded during monsoon season. In other rivers of the Garhwal region, the catch percentage is quite low and is between 0 and 1% of the total catch.
The total catch per unit effort (CPUE) of T. putitora ranged from 4.3 to 270.6 g/man/h in the selected rivers (Fig. 7). The highest CPUE was obtained from the river Nayar. The total CPUE ranged from 340.1 to 1 891.0 g/man/h.
Fig. 7 - Mean CPUE of total fish population and Tor putitora in different rivers of Garhwal region
In terms of weight, maximum catch size of mahseer varied between 200 and 400 g. Only during July-September were mahseer above 1.0 kg weight recorded from the rivers Nayar and Song. From the other selected rivers the catch of mahseer was very low, with weight range of 200 to 500 g. Overall, weight range of T. putitora during the period of investigation ranged from 25 to 1 650 g, their body length ranged from 10.5 to 52.5 cm and width from 2.0 to 9.5 cm (Table 7). The harvested golden mahseer were in the age group of under one year to above three years.
An appraisal of the ecosystem characteristics of the selected rivers/streams of the Ganga river system in the Garhwal region of Central Himalaya reveals that all spring-fed rivers are 'placid eurythermal', with increased range of temperature. The glacier-fed rivers, on the other hand, can be classified as 'torrential stenothermal'. Singh et al. (1991) have recognized the altitudinal range of 600-1 200 m as the mahseer zone. All the sampling sites of the selected rivers in the present study were located in the range of 425-1 000 m altitude. In general, the glacial-fed streams Bhagirathi and Bhilangana had low temperature, steep gradient, swift water current, high dissolved oxygen content and mildly acidic to slightly alkaline pH. All these factors together determine the distribution and abundance of periphyton and benthos.
Table 7
Total weight, total length and width of the harvested mahseer from the selected streams of Garhwal Himalaya
Total weight (g) |
Total length (cm) |
Width (cm) |
25 |
10.5 |
2.0 |
50 |
16.0 |
2.6 |
75 |
17.0 |
3.0 |
100 |
20.0 |
3.0 |
150 |
24.0 |
4.0 |
175 |
23.0 |
4.3 |
200 |
23.0 |
4.4 |
350 |
28.5 |
5.0 |
550 |
32.0 |
5.5 |
800 |
39.5 |
7.8 |
1 000 |
49.2 |
9.0 |
1 650 |
52.5 |
9.5 |
The spring-fed streams of the Central Himalayan region have relatively high temperature (10.0 to 27.5°C), low current velocity (0.4 to 1.2 m/s), and a relatively confined channel basin (4.4 to 18.5 m). The dissolved oxygen content was also lower than in the glacier-fed streams (6.6 to 8.8 mg/L). However, pH was slightly higher (7.0-7.9) and total alkalinity was much higher (0.9 to 184.3 mg/L). Current velocity and water temperature greatly influence the periphyton (aufwuchs) density in the streams of Central Himalaya. It was higher in spring-fed streams than glacier-fed ones. The river Nayar had higher plankton population than the rivers Bhagirathi and Bhilangana. Singh et al. (1991) and Dobriyal and Singh (1989) also reported a similar trend in some hill streams of Garhwal Himalaya.
Like periphyton, the macrobenthic invertebrate fauna was also higher in spring-fed streams. The higher temperature, moderate current, good periphyton and allochthonous matter coupled with a high substrate heterogeneity enhance the density of macrobenthic fauna in spring-fed streams. Dobriyal and Singh (1990) reported that this provides a good base for the development and growth of minor carp fishery in Central Himalayan waters.
The golden mahseer is the most important game and food fish in the Central Himalaya. It contributes greatly to the commercial fishery in the foothills. The fish migrates considerable distances upstream in the search of suitable spawning grounds (Badola and Singh, 1984; Nautiyal and Lal, 1984; Singh, 1988). However, once found in abundance, the stocks of the Himalayan mahseer are depleted to the extent that it is now considered as an endangered species (Singh et al., 1991). The decline of mahseer fishery has also been reported from the other Himalayan waters such as the Ganga river system (Chauhan et al., 1992), Brahmaputra river system (Dey, 1992), Govind Sagar reservoir (Johal and Tandon, 1981), Kumaun lakes (Sharma, 1991) and some other waters.
The present investigations also reveal that the population of golden mahseer has greatly declined in the waters of Western Central Himalaya. It contributes significantly to the fishery only in the spring-fed river Nayar where it comprises 32.8% of the total catch. The second best contribution (9.7%) was in the river Song. In other streams the contribution ranges only between 0.8 and 3.1%. The brooders, yearlings, fry and fingerlings of golden mahseer were observed in the river Nayar only. The average seed density was between 300-400 no/m2 at the confluence of the rivers Nayar and Ganga at Vyasghat (Fig. 1).
Himalayan mahseer population undertakes contranatant migration from the foothill sector of the Ganga, often ascending into the rivers Bhagirathi and Bhilangana. These major tributaries serve as the only routes through which the fish can have easy access to the spring-fed placid streams providing congenial environment for the fish to breed (Nautiyal and Lal, 1984). However, the present observations reveal that only Nayar is a potential mahseer spring-fed stream in the Western Central Himalayan region. However, the size of the catch was also very low from Nayar (25 to 1 650 g) as per observations during the period of investigation.
The factor that has brought Himalayan mahseer to the brink of extinction is indiscriminate killing of juveniles and brooders.
Mass slaughter of fish through toxicants and dynamite is common, particularly in uplands. Fishing by fixed gears is also a common example of indiscriminate fishing. Intensification of fishing effort during the pre-monsoon period, when water level in rivers is low, adds to the problem. Changes in the habitat due to construction of dams, barrages and weirs under river-valley projects adversely affect the biology of this fish.
Prospects of mahseer fishery development
In spite of depletion of the population of golden mahseer, there is tremendous scope to develop its fishery for both commercial and recreational purposes. Based on the present investigations a three-fold strategy is suggested for the development of the fishery of Tor putitora in Garhwal Himayala:
(i) Preservation of existing stocks:
Fish protection in the rivers and other water systems of the region will be helpful in preserving valuable fish genetic resources (Singh and Singh, 1991). The following conservation measures are suggested:
proper stock assessment should be undertaken for determining the present status of commercial fishery and its subsequent level of exploitation,
ban on indiscriminate fishing should be strictly enforced,
closed seasons should be rigidly enforced and there should be a total ban on capture of juveniles and spawners,
selected stretches of water bodies should be declared as mahseer sanctuaries.
(ii) Promotion of natural propagation:
the spawning and nursery habitats of Himalayan mahseer in small hill streams, which contain abundance of benthic entomofauna and serve as natural nurseries for the breeding population of mahseer, should be identified and protected,
foliage cover should be provided on banks of streams to prevent wide fluctuations in temperature and to prevent soil erosion,
artificial pools should be created in rivers for better spawning conditions,
hindrances to spawning migration should be cleared,
collection of post-larvae and fry/fingerlings, their rearing up to advanced fingerling stage on formulated feeds, and restocking in natural waters for better survival should be the future strategy for enhancing mahseer stocks in Himalayan waters.
(iii) Hatchery development and seed production of Tor putitora
Successful breeding and seed production programme of Tor khudree has been carried out for two decades at the Fish Seed Farm of the Tata Electric Company at Lonawala (Ogale, 1992). However, efforts made to induce-breed pond-reared broodstock of T. putitora by hypophysation have not been very successful (Joshi, 1994). Further, the availability of broodstock from nature is still minimal. The studies on the maturity and fecundity have shown that eggs mature in batches (Bhatnagar, 1967). The total number of eggs taken from females varied from 500 to 10 000 (Sehgal, 1991).
For the protection, rehabilitation and aquaculture of Himalayan mahseer the following is needed:
a reliable breeding technology be developed, trial tested and replicated,
hatchery, nursery and rearing technologies of T. putitora be developed,
selective breeding of mahseer using brooders from nature be done for stock improvement,
mahseer hatcheries be established near the stocking sites,
hatchlings of mahseer be raised on formulated diets up to fingerling stage.
The hatchery-produced fingerlings of mahseer should be stocked regularly in selected streams and lakes to replenish their mahseer fish stocks and the feedback data from mahseer fishery should be collected and analysed.
There is good scope for the extensive and intensive culture of T. putitora in the Garhwal Himalaya. The streams located in the suitable altitudinal zone can be selected for the culture of Himalayan mahseer. There are innumerable spring-fed perennial streams where water could be diverted into narrow ponds or raceways alongside such streams. The fish can be raised on protein rich pelleted feed. The development of hatchery production of fish seed and its ranching in rivers and lakes of Central Himalaya can successfully bridge the gaps in production. Mahseer aquaculture in suitable localities should also be tested through pilot studies.
Acknowledgements
The present work was carried out under the National Agriculture and Technology Project (NATP). The financial assistance provided by the ICAR is acknowledged. We are also thankful to the Dean, Fishery Sciences, who permitted the use of ponds of the Fish Farm. The assistance rendered by Ms Archana in the preparation of the manuscript is gratefully acknowledged.
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