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10. RAJASTHAN

Rajasthan is one of the border States of India, sharing the country's frontier with Pakistan in the west and northwest. The State encompassing an area of 342 239 km2 shows great physiographic variations. Six distinct geographical divisions are clearly discernible. The sprawling western region is arid and virtually a desert land, where no reservoirs are located. The semi-arid region between the Aravalli ranges and the western deserts runs across the state from Jalor the Jhunjhunu. Southern part of this region is drained by the Luni river, while the northern part remains dry. The Indira Gandhi Canal, carrying water from Bhakra dam passes through this region in the Ganganagar district. The Aravalli region is undulating hill country dominated by mountains. Taking advantage of the uneven terrain, a large number of small impoundments have been created in the region, especially in the districts of Pali, Udaipur and Sirohi. The eastern region is extensively drained by the Banas River and its many tributaries. This region is rich in industries with a large number of reservoirs, especially in Sawai Madhopur, Bundi, Alwar and Bharatpur districts. The southern region of the State, embracing the districts of Banswara, Chittorgarh, Rajsamand, Jhalwara and Kota consists of stony uplands setting ideal sites for water resources development. The maximum number of man-made lakes are situated in this region. The Chambal ravine region lies along the river Chambal, forming the boundary between Rajasthan and Madhya Pradesh.

Alluvial soil occupies the northeastern parts of Rajasthan, comprising the districts of Alwar, Bharatpur, Jaipur, and Sawai of Madhopur. The State receives rain from both the Arabian Sea and the West Bengal branches of the southwest monsoon, 80 to 90% of the rainfall occurrs during June to October. On an average, the State receives 53.6 cm of rainfall per annum.

10.1 RESERVOIR FISHERIES RESOURCES

Rajasthan has about 153 444 ha of water area under reservoirs, more than a third of which fall under the small category. Of the 423 reservoirs listed, only four are in the large category, while the small and medium sized reservior number 389 and 30 respectively. Rajsamand, Banswara and Chittorgarh a have a large number of small reservoirs, though they do not contribute much to the total area. The large reservoirs, viz., Rawatbhate (19 600 ha) in Chattisgarh district, Bajajsagar(13 500 ha) in Banswara district, Jaisamand (7 600 ha) in Udaipur district and Kadana (9 000 ha) in Banswara and Dungarpur districts, cover more than 32% of the total water area (Fig. 10.1; Table 10.1).

Fish production from reservoirs of Rajasthan

Among the 97 reservoirs for which details of current production (1993) are available, seventy-eight small reservoirs distributed in 18 districts produce fish to the tune of 0.1 to 467 kg ha-1 of fish (Table 10.2). Bankli reservoir in Jalore district is the most productive reservoir with a yield of 316 kg ha-1. Average fish yield is high in the reservoirs of Ajmir (260 kg ha-1), Pali(137 kg ha-1), Sawai Madhopur(113 kg ha-1) and Jodhpur districts (109 kg ha-1). Bilwara district with a yield ranging from 0.1 to 7 kg ha-1 (average 2 kg ha-1) and Bundi district with 1 kg ha-1 are among the poorest districts in reservoir yield.

Table 10.1 District-wise distribution of reservoirs in Rajasthan
DistrictSmall (< 1 000 ha)MediumLargeTotal
No.AreaNo.AreaNo.AreaNo.Area
Chittogarh373 92633 439119 6004126 965
Ajmer3150    3150
Banswara424 910--113 5004318 410
Bundi113 73923 237  136 976
Jhalwara151 392    151392
Dungarpur143 224--1 9 0001512224
Sirohi561733189  83 806
Pali323 82212 000  335 822
Barana2800    2800
Bikaner  11 800  1800
& Ganganagar        
Sikar7357    7357
Dausa31 39011 360  42 750
Bharatpur91 06111 160  102 221
Jodhpur3530    3530
Jaisalmer  13 000  13 000
Jalore2280    2280
Rajsamand936 413    936 413
Sawai306 58811 619  318 207
Madhopur        
Alwar61 76323 000  84 763
Dholpur61 28212 402  73 684
Ganganagar135 800613 800  1919 600
Udaipur314 057  17 2863211 343
Kota313722261  52 398
Tonk101 23523 000  124 235
Jaipur6*200*11 260  71 460
Barmer1100----1100
Bhilwara545823 300--73 758
Total38954 2313049 827449 386423153 444

* Area of only one reservoir Compiled from the data provided by the State Govt. of Rajasthan

Current fish production for 17 medium reservoirs, covering a waterspread of 24 506 ha, is available. Medium reservoirs of the State have yields ranging from 0.2 to 100 kg ha-1. The 2 000 ha Jawi reservoir in Jaisalmer district and 1 325 ha Gambhiri reservoir in Chittorgarh district are very productive with yield of 100 and 60 kg ha-1 respectively. On the whole, medium reservoirs of Rajasthan have a yield of 24.47 kg ha-1.

Among the large reservoirs the Mahibajaj and Kadana produce 40 and 80 t of fish (3 and 9 kg ha-1 respectively) (Table 10.3). Fisheries management in some reservoirs in the State under the Rajasthan Tribal Areas Development Corporative Federation is good (Sreenivasan. 1993). These reservoirs receive financial support from NABARD in the form of material inputs and share capital.

The average fish yield of 24.89 kg ha-1 from the reservoirs of Rajasthan is one of the highest in India. This is the result of concerted efforts towards yield optimisation, already launched by the State (Jhingran, 1989b). However. detailed ecological investigations of reservoir ecosystems are still very few.

Table 10.2 Fish production in small resrvoirs of Rajasthan
DistrictNumber of reservoirs examinedYield range (kg ha-1)Average yield (kg ha-1)
Ajmer3171 to 467260
Alwar43.3 to 5016
Banswara104 to 5825
Barana25 to 209
Barmer12020
Bhilwara50.1 to 72
Bundi111
Chittorgarh134 to 19019
Dausa350 to 10064
Dungarpur53 to 85
Jalore1316316
Jodhpur267 to 160109
Pali1137137
Rajsamand27 to 10576
Sawai Madhopur1129 to 377113
Tonk236 to 4439
Udaipur713 to 6030
Bundi52 to 7222
Pooled78-46.43

* Based on the data provided by the State Fisheries Department.

Table 10.3. Fish production in medium and large reservoirs of Rajasthan
DistrictReservoirArea (FRL)Yield kg ha-1)
Medium reservoirs
AlwarJaisamand1 20010
-do-Mangalsar1 8005
BanswaraUrvania1 0006
BharatpurBaretha1 16012
BhilwaraMeja1 5001
BikanerGhaghria1 8000.2
ChittorgarhGambhiri1 32560
-do-Wagan1 10027
-do-Meja1 0008
-do-Morel1 36015
GanganagarGhaggar1 80055
JaisalmerRD 1 3563 0000.2
KotaAlania1 20013
-do-Sawanbhadan1 06119
-do-Jawi2 000100
TonkMash1 00065
-do-Tendisagar1 20015
Medium reservoir pooled 24 50624.47
Large reservoirs
BanswaraMahibajaj13 5003
Dungarpur/Kadana9 0009
Banswara   
Large reservoirs pooled 22 5005.3

10.2 RAMGARH RESERVOIR

The Ramgarh reservoir is situated at a distance of 72 km to the north of Jaipur at 27° 12'N and 75° 32' E at an elevation of 132.5 m above MSL. Construction of the dam across the river Banganga, a tributary of the Yamuna, commenced in 1897 and the reservoir filled during 1903. The area experiences an annual rainfall of about 53.6 cm which sometimes goes up to 75 cm. The catchment area of 769 km2 drains mostly the Aravalli hill ranges. At full reservoir level, reservoir covers 1 260 ha and has a maximum length of 7 km. The capacity of the reservoir is 59 million m3, the maximum and mean depths being 18 and 4.6 m respectively.

Ramgarh reservoir has a shoreline of 22.8 km and the shoreline development is 1.81. The volume development index is 0.61. Gopal at el. (1981) reported a heavy soil erosion and estimated 3.5 m of silt deposition on the reservoir bottom during the last 75 years, resulting in a reduction of its water volume. Jhingran(1989b) gives an account of ecology, production propensities and fisheries of Ramgarh. An evaluation of productivity and trophic status of the reservoir has been attempted to facilitate planning for fishery management.

Physico-chemical attributes

The basin soil is alkaline and contains moderate concentration of organic carbon (0.5–1.0%), available nitrogen (26.6–88.2 mg 100 g-1) and low levels of available phosphorus (0.04–1.1 mg 100 g-1). However, phosphate concentration of 0.11–0.16 mg 100 g-1 in the soil is relatively high. Calcium carbonate (12.0–14.5%) in soil is medium high. Thus, the edaphic features of the reservoir place it in the productive category (Table 10.4). The total alkalinity (129.33 to 198.66 mg 1-1), total dissolved solids (215.66 to 554.0 mg 1-1), and specific conductivity (307 to 791 μmhos) of the reservoir water indicate a high primary productivity. Transparency is variable spatially and seasonally. The inorganic turbidity results from influx of colloidal particles and suspended silt in flood water and the organic turbidity from phytoplankton blooms.

Water temperature ranges from 18°C (January) to 32°C (June-July) with an annual fluctuation of 14°C. The wide seasonal variation in water temperature has a bearing on the heat cycle of the reservoir. The annual heat budget is found to be 82.60 million cal m-2. The heat content fluctuates between 64 (in winter) and 146.6 million cal m-2 (in summer). Thus, the amount of energy required to maintain the annual heat cycle of the reservoir appears to be of a high order. The nutrient status of the reservoir water with respect to phosphate, nitrate and silicate is optimal. On many occasions, phosphate is in the range of 0.11 to 0.16 mg 1-1. Nitrate nitrogen content of 0.22 to 2.13 mg 1-1 (average 0.90 mg 1-1) is much higher than in many other reservoirs in India. Free ammonia is very low, the range of variation being traces to 0.1 mg 1-1. Silicate values vary from 5.6 to 18.46 mg 1-1 (average 11.53). Organic matter in the range of 4.40 to 8.05 mg 1-1 (average 6.5 mg 1-1) indicates a high concentration of oxidisable organic substances in water, yet another important parameter reflecting the productive nature of water. Chloride is fairly high in the reservoir (38.66–76.0 mg 1-1) but fluoride is low (traces to 0.7 mg 1-1).

Hydrological parameters clearly suggest the high productivity potential of Ramgarh reservoir. It is interesting to note that despite poor soil quality, especially with respect to phosphorus, the water remains rich in nutrients. Geochemical characteristics of the watershed and climatic factors like rainfall determine the productive potential of the reservoir to a considerable extent. The rich water quality reflects the transport of allochthonous dissolved nutrients. A high rate of runoff seems to favour the nutrient enrichment of the reservoir. There are very little spatial variations among different zones of the reservoir in respect to the limnochemical parameters.

Table 10.4. Important limno-chemical features of Ramgarh reservoir
ParametersRangeAverage
SOIL QUALITY
pH7.4–8.68.1
Organic carbon(%)0.15–1.050.38
Available nitrogen (mg 100 g-1 soil)26.6–88.252.5
Available phosphorus (mg 100 g-1 soil)0.04–1.10.57
Free calcium carbonate (%)15–2216.8
Specific conductivity (μmhos)200–1000475.5
WATER QUALITY
Water temperature (°C0)18–32-
Transparency (cm)80–108-
pH8.3–8.68.4
Alkalinity (mg 1-1129.33–198.66165.63
Calcium (mg 1-1)13.33–25.020.32
Magnesium (mg 1-19.33–23.015.52
Total dissolved solids (mg 1-1215.66–554.0359.17
Specific conductivity (μmhos)307.0–791.0513.0
Dissolved organic matter (mg 1-1)4.40–8.056.50
Dissolved oxygen (mg 1-1)6.3–9.28.06
Chlorides (mg 1-1)38.66–76.043.06
Fluorides (mg 1-1)Tr-0.70.28
Phosphates (mg 1-1)Tr-0.40.052
Nitrates (mg 1-1)0.22–2.130.90
Free ammonia (mg 1-1)Tr–0.10.025
Silicate (mg 1-1)5.6–18.4611.53

(After Jhingran, 1989b)

Biotic communities

The reservoir with a favourable environment for organic productivity harbours rich biotic communities at the primary and secondary producer levels, comprising plankton, macrophytes and benthos. The occasional blooms of phytoplankton and rapidly growing macrophytes and sedentary algae are the hallmarks of the ecosystem.

Plankton

Diatoms constitute the dominant group among phytoplankters and form on an average 19.08% (by number) of the total population. Two pulses, one in January (34.9%) and the other in March, though of a lesser magnitude, are observed. The main taxa in order of abundance are Navicula radiosa, Nitzschia spp., Synedra ulna, Fragilaria sp., Cyclotella sp., Diatoma sp., and Rhopalodia sp., Gyrosigma sp., and Gomphonema sp.

The green algae, as a group, form 15.0% of the total planktonic population and is mainly represented by Chlorella vulgaris, Selenastrum gracile and Ankistrodesmus sp. in the order of abundance. Other species, though insignificant in numbers, are Crucigenia tetrapedia, Microspora sp., Ulothrix sp., Oedogonium sp., Pediastrum duplex and Scenedesmus spp. Maximum density of this group is observed in March (23.0%) and minimum in July (7.2%).

The blue-green algae rank third in order of abundance and fluctuate from 19.1% in January to 5.7% in June. On an average, the group constitutes 10.89% of the total plankton population. Two pulses, one in January and the other in August are witnessed. The species in order of abundance are Raphidiopsis indica, Phormidium spp., Merismopedia spp., Microcystis aeruginosa, Nostoc sp., Oscillatoria spp. and Aphanocapsa pulchera. Lost concentration of 6.3% is recorded in August and, on an average, the blue-greens constitute 10.7% of the total planktonic population.

Cladocera is the most abundant group of Crustacea and, on an average, forms 58.4% of the crustacean population and 17.9% of the total plankton. It is most abundant in February (31.8%) followed by July (29.3%) and October (29.6%). The main genera are Ceriodaphnia, Simocephalus, Chydorus, Daphnia and Moina in order of abundance. Copepods form 36.9% of the crustacean population and 12.5% of the total plankton. Their population remains low during winter months and increases in June (29.0%) and August (21.6%). Diaptomus., Cyclops, Mesocyclops and their larvae form the main constituents of this group. Ostracods are very poorly represented and form only 4.7% of the crustacean population and occur only in April, August, and December. Cypris is the only representative of this group.

Rotifers, forming 13.9% of the total plankton, are represented by Brachionus, Keratella, Lecane, Asplanchna and Filinia in the order of abundance. They are more abundant in July (24.60%), followed by October (24.2%), but low in numbers in January (5.3%). In general, two peaks, one each in pre- and post-monsoon months, are observed.

Benthos and aquatic macrovegetation

The benthic fauna fluctuates from 933 to 2 453 individuals m-2. The three peaks in the benthic populations coincide with the winter, summer and post-monsoon seasons falling in the months of December, June and September respectively. The main constituents of benthos are insects, molluscs, oligochaetes, and miscellaneous fauna. These groups form, on an average, 59.0%, 26.4%, 12.7%. and 1.9% respectively of the total benthic population.

Density of aquatic macrovegetation ranges from 715 g m-2 in September to 2 193 g m-2 in April, (averageb 1 429 g m-2). Maximum abundance is recorded from January through March and a peak of small magnitude in June and July. The abundance of the macrophytes is found to have some direct relation with water level of the reservoir and an inverse relationship with water temperature. Hydrilla, Ceratophyllum, Potamogeton, Najas, Azolla and Ipomea are the major macrophytes encountered in Ramgarh reservoir.

Fish fauna

The reservoir harbours rich fish fauna, represented by 74 species, belonging to 17 families and 9 orders (Mahajan et al., 1984). Cypriniformes alone has 54 species. Nine species contribute significantly to commercial fisheries of reservoir viz., Catla catla, Labeo rohita, L. calbasu, Cirrhinus mrigala, Wallago attu, Channa marulius, L. bata, Notopterus notopterus, and Puntius sarana.

C. catla subsists mainly on zooplankton whereas L. rohita, L. calbasu, and C. mrigala live predominantly on detritus and algae. The food spectrum of P. sarana is very wide. Besides detritus and algae, it consumes gastropods, bivalves, and insect larvae. W. attu and marulius are voracious predators, while N. notopterus is an omnivore, subsisting on plant detritus, insect larvae, prawns and weed fishes.

A high shore development, relatively low mean depth, optimum nutrient levels, high concentration of phytoplankton, increasing aquatic macrophytes, and well-established zooplankton and benthos exert augmentative effects on the productivity of the reservoir at various trophic levels and hence the fishery. The reductive factors that exert stress on the system are the low inorganic transparency during floods and relatively low species diversity of plankton, benthos and fish.

Community metabolism

Light energy available at the water surface of the reservoir ranges from 115× 104 cal m-2 day-1 (December) to 238 × 104 cal m-2 day-1 (May) with an average value of 183 × 104 cal m-2 day-1. The energy fixed by producers is in the range 3 969 m to 12 274 cal m-2 day-1. Only 0.17 to 1.01% of the light energy available on the surface of the reservoir is fixed through primary production (Table 10.5). The average rate of energy transformation by producers in the reservoir is 8 236 cal m-2 day-1 (0.49% of light).

The fish faunistic spectrum of the reservoir being biased in favour of detritus feeders, the main pathway of energy flow in Ramgarh is through the detritus chain. Of the 98 532 k cal ha-1 yr-1 of energy output from the reservoir, the detritivores and primary consumers contribute 50 652 (51.4%) and 14 184 k cal ha-1 yr-1 (14.4%) respectively (Table 10.6). The share of secondary consumers is 15.9% and the tertiary consumers account for 18.3% of the energy. Thus, almost 66% of the energy output from the reservoir is contributed by primary consumers (mainly detritivores), owing to their dominance. This points towards a better utilisation of energy, than in many other Indian reservoirs.

The energy conversion efficiency, from light to fish (0.00146%) or primary fixed energy to fish (0.33%), observed in Ramgarh is better than the values observed in many other Indian reservoirs. The exploitation efficiency which gives the extent of utilization of net energy fixed by producers as fish is 0.44%.

Table 10.5. Energy transformation through primary production in Ramgarh reservoir
MonthsIncident visible solar energy (cal m2 day-1)Gross productionNet productionPhotosynthetic efficiency
(%)
Carbon (mg Cm-2 day-1)Energy (cal m-2 day-1)Carbon (mg Cm-2 day-2)Energy (cal m-2 day-1)
January1 220 0001249.9212 274999.969 8201.01
February1 490 0001218.7211 968968.649 5120.80
March1 860 0001218.7211 968968.649 5120.64
April2 110 0001156.2011 354937.329 2040.54
May2 380 000874.928 592750.007 3650.36
June2 260 000750.007 365349.963 4370.33
July2 330 000404.163 969266.322 6150.17
August2 210 000487.204 784270.722 6580.22
September1 980 000666.006 540308.803 0320.33
October1 630 000819.968 052437.404 2950.49
November1 330 000645.726 310364.443 5790.47
December1 150 000572.765 624322.923 1700.49
Average1 830 000838.378 236578.765 6830.49

(After Jhingran, 1989b)

Table 10.6. Photosynthetic energy fixation and energy conversion in Ramgarh reservoir
Latitude27°12'N
Total visible solar energy (cal m-2 yr-1 × 105)6 680
Photosynthetic production energy (cal m-2 yr-1 × 106)3.007
Efficiency of transformation of light to chemical energy (%)0.49
Fish production as energy (cal m-2 yr-1)9 853
Conversion of energy (%) fish/photosynthesis0.33
Fish/light0.00146
Photosynthesis (g C m-2 yr-1)306.00
Fish yield (g C m-2 yr-1)0.821
Conversion (%)0.24
Exploitation efficiency (Energy output
Energy fixed× 100)
0.44%

(After Jhingran, 1989b)

Fish production potential

The morpho-edaphic index(MEI) of Ramgarh reservoir, based on the average rate of total dissolved solids and the mean depth, is 69.68. This value of MEI suggests a fish production of 200 kg ha-1 . An alternative estimate derived from trophodynamic and energy flow model indicates a yield potential of 202 kg ha-1 (Jhingran, 1989b). Past catch records reveal that 80% of the standing stock is harvestable through maximum efficiency of fishing units. A yield of 160 kg ha-1 is not difficult to achieve with the help of a rational stocking programme. Thus, the actual mean fish yield of 82.11 kg ha-1 is only 40% of the potential.

Stocking

The energy fixed at the primary producer level is not transferred directly to higher trophic levels for want of adequate populations of phytophagous fishes in the reservoir. This calls for stocking suitable species to utilize the vacant niches. Moreover, maintenance stocking should be the top priority, owing to the reported feeble natural recruitment in the reservoir. Stocking of major carps, on a continuous basis, would prove beneficial in balancing wide annual fluctuations in natural recruitment. It would also help maintain the desired density of the component species during the unfavourable years when they are unable to reproduce.

Stocking of Indian major carps, has been erratic. The impact of stocking on the fisheries of Ramgarh reservoir can not be evaluated in the absence of a regular stocking policy. According to the available records, a total of 435 681 fingerlings of rohu, mrigal, and catla were stocked in the reservoir during February 1983– April 1984 (Table 10.7). This stocking, which works out to be 350 fingerlings ha-1, appears to be devoid of any rationale other than the availability of seed. No standards on the size of the stocked material and the reason of stocking have been maintained, thereby ignoring these vital considerations.

Table 10.7. Stocking in Ramgarh reservoir during 1983 to 1984
Species stockedNumber (%)Size range (mm)
L. rohita325 768 (74.75%)60–220
C. mrigala82 803(19.00%)60–220
C. catla27 116(6.25%)100–140

(After Jhingran, 1989b)

Optimum number of fish to be stocked per unit area in Ramgarh reservoir has been worked out, based on the potential fish yied and the average individual growth rate of the species to be stocked(Jhingran, 1989b). Giving allowance for natural mortality and possible escapement of fingerlings through irrigation channel, 530 late fingerlings of catla, rohu, mrigal and calbasu (4:2:2:2) ha-1 are required to be stocked. Thus, the number required would be 371 000 fingerlings, on the basis of an average waterspread of 700 ha.

Fisheries

Fish catch from Ramgarh varied from 12.6 to 98.9 t during 1969–70 to 1984–85 (Table 10.8). The fish output during the fishing periods of 1983–84 and 1984–85 is 55 984 and 58 967 kg respectively, equivalent to 79.98 kg ha-1 and 84.23 kg ha-1 on the basis of a mean waterspread. With the average yield of 77.8 kg ha-1, Ramgarh can be placed amongst the productive reservoirs of the country. Cirrhinus mrigala contributing 33% of the catch by weight is the dominant species of the commercial catches followed by C. catla (15%) and Labeo rohita (14%) (Fig. 10.2). However, N. notopterus, L. bata and P. sarana have an edge over others in numerical terms.

Artificial impoundments pose many obstructions to successful fishing operations. In Ramgarh, the tree stumps, boulders and other submerged obstacles limit the use of many a fishing gear. Fishing in the reservoir is carried out by the commercial fishing parties who deploy mainly gill nets and shore seines, with limited use of cast nets, traps, and hook and line.

Gill nets of mesh size 37.5, 50.0, 62.5, 75–100.0 and 112.5 to 150.0 mm account for most of the catch. Of the total of 73 068 fishes weighing 55 984 kg. caught from the reservoir during 1983–84, the share of gill nets was 58 444 (80%) by number and 35 770 kg (63.9%) by weight. Gill nets of smaller mesh bars such as 37.5 and 50 mm are effective in catching W. attu, P. sarana, N. notopterus, L. bata and C. marulius.

Table 10.8. Estimated catch for different years in Ramgarh
YearTotal catch (kg)Yield (kg ha-1
1969–7057 66982.38
1970–7142 91561.31
1971–7212 62518.03
1972–7355 60079.43
1973–7449 46870.67
1974–75  
1975–7672 760103.94
1976–7773 651105.22
1977–7898 943141.35
1978–7938 60055.14
1979–8060 00085.71
1980–8130 30043.29
1981–82. 
1982–83. 
1983–8455 98479.98
1984–8558 96784.23
  Average 77.80

n.a. - Data not available (After Jhingran, 1989b)

The fishing effort in terms of gear and manpower varies from month to month and the same is the case with the net fishing days per month, which vary from 9 during 1983–84 to 7 in 1984–85.

Commercial fishing records indicate that each fisherman generally catches 1 t of fish per yr from Ramgarh, as opposed to the harvest level of 2 to 4 t fish per yr obtained from some other Indian and African reservoirs. Assuming the potential of the reservoir to be 200 kg ha-1, 100 to 160 kg ha-1 can safely be extracted, depending on the efficiency of fishing units and desired density of stock maintained through stocking. Taking the average productivity of gill nets as 8kg 1 000 m-2, it has been estimated that 12 000 to 20 000 m2 of gill net area, manned by 70 to 112 fishermen and 35 to 56 boats shall have to be deployed for obtaining the targetted yield.

The fishing rights of the reservoir are leased out to contractors against a royalty paid to the Government according to the species of fish caught. The fishermen get wages for their labour and all the inputs like boats, gill nets, drag nets, traps and hooks and lines are provided by the contractors. The restrictions imposed by the Fisheries Department are limited to the mesh size, by not allowing the operation of nets < 37.5 mm mesh bar and the observance of a closed season in July and August to prevent indiscriminate killing of young and brood fishes.

Figure 10.2

Figure 10.2 Percentage composition of fish catch in Ramgarh

During 1983–84, a total of 48 fishermen worked for 145 days and earned Rs. 1 64 628. In 1984–85 fishing season, a work force of 61 fishermen toiled for 78 days for the contractor and earned Rs. 1 65 858. During the two fishing seaons, the net annual income for each fisherman was only Rs. 3 032.

A preliminary probe into notional cost and return functions reveals that fishermen, in the event of organising themselves into cooperatives, would have been better placed in terms of income. During the fishing season of October 1984 to June 1985, 48 fishermen would have incurred an expenditure of Rs. 69 000 on fishing crafts and gear, and the annual capital cost of Rs. 9 700. This, along with the opportunity cost, maintenance and repair, marketing cost and other miscellaneous cost would have added up to a total input cost of Rs. 162 500 to harvest fish worth 745 243. Thus, a net income of Rs. 5 82 743 could have accrued to 48 fishermen giving each fisherman an annual income of Rs. 12 140.48. Even after leaving a margin of 10% for royalty to the State Government as auction value, the fishermen would have earned more than three-fold of what they received as wages from the contractor (Table 10.9). Similar figures have been obtained for the fishing period from February to June 1984 when the net income worked out to be Rs. 10 435.

Ramgarh is a medium-size irrigation impoundment where fishing operations are for a limited period. The reservoir cannot offer employment for the whole year unlike the very large reservoirs. Ecological data indicate a potential for raising the yield from the current average of 77.4 kg ha-1 to 150 kg ha-1. In that event, there is a fair possibility of creating employment avenues for an additional 48 fishermen families.

Table 10.9. Notional cost and return functions for fishing activities in Ramgarh reservoir
 Initial outlay cost (in Rs.)Annual capital
A. Fixed cost (FC)
1. Boats 10 small  
1 large57 000=005 700=00
2. Nets12 000=004 000=00
Total fixed cost (TFC)69 000=009 700=00
B. Variable cost (VC)
3. Opportunity cost @ Rs. 10 per day or Rs. 1.25 per hr (145 × 48 × 14 × 1.25) 1 21 80=00
4. Maintenance and repair 1 000=00
5. Marketing cost 24 000=00
6. Miscellaneous 6 000=00
Total variable cost (TVC) 1 52 800=00
Total cost (TC=TFC+TVC) 1 62 500=00
Total income (TI) 7 45 243=00
Net income (TI-FC) 5 82 743=00
Net income per fisherman* 12 140=00

* Without accounting for auction cost (After Jhingran, 1989b)

10.3 CHHAPARWARA RESERVOIR

Chhaparwara is a small reservoir on the seasonal Mavshi river, the major portion of which dries up during the summer months. It was commissioned in 1894, mainly for irrigation purposes. Located at the geographical ordinates 26° 37'N and 75° 15'E, the lake extends to 200 ha at full level and can hold 35 million m3 of water received from a catchment area of 515.2 km2. The mean depth is 1.7 m.

Being a small, shallow, seasonal irrigation impoundment, high flushing rate. The determinants of primary production are allochthonous detritus and sessile algae. Limnological data available for this reservoir are scanty. Jhingran (1989b) made an assessment of the productivity based on total alkalinity (76 to 100 mg-1), calcium (20 to 35 mg-1) and phosphate (0.11 to 0.165 mg-1) and he considered it to be fairly productive (Table 10.10).

The bottom soil is characterised by low organic carbon (0.15 to 0.34%), rich available nitrogen (36.6 to 61.6 mg 100 g-1) and poor available phosphorus (1.1 to 1.6 mg 100 g-1). The higher phosphate concentration in water emphasises the importance of allochthonous enrichment. The low phosphorus content of the soil perhaps indicates rapid assimilation of all available phosphorus in the biota.

Biotic communities

Fish food resources are reported to be uniformly distributed at all depths and zones of the reservoir (plankton 3 100 to 20 100 individuals 1-1; benthos 110 to 947 individuals m-2). Loss of nutrients through irrigation canal seems to be amply replenished by allochthonous detritus entering the reservoir. Production rate is high on account of high water temperature and shallowness. High shore development and larger substratum for photosynthetic organisms are the other augmentative factors.

Community metabolism and fish yield potential

The net energy fixed by producers in Chhaparwara ranges between 2 380 and 6 137 ca m-1 day-1. About 49 to 76% of the gross energy fixed by the producers is stored by them. The energy assimilation ratio is higher than that observed in some other Indian reservoirs (Bhavanisagar, Nagarjunasagar, Rihand, etc.). The rates of energy conversion potential both from light to fish (0.0014%) and from primary energy to fish (0.39%) are also higher. The fish yield potential of the reservoir is estimated at 158 kg ha-1, the actual yield is 79 kg ha-1. Thus, only 50% of the potential is actually being harvested, leaving enough room for enhancing fish yield.

Fisheries management

Chhaparwara reservoir, in stocked by the State government, with fingerlings of major carps on an arbitrary basis. Attention has not been given to suitable time, number and sizes of fingerlings to be stocked, perhaps owing to dearth of stocking material and insufficient knowledge of the production processes of the ecosystem. Elsewhere, intensive stocking has proved to be highly advantageous for small reservoirs (Keetham, Loni, Gulariya, Bachhra), which dry up completely during summer months or where the water level declines so much that complete harvesting is possible. In such reservoir, there exists a direct correlation between the stocking rate and catch, and a similar strategy could be applied for Chhaparwara reservoir.

The catch records of the reservoir do not show any relation between stocking intensity and catch. Harvesting is reported to have been done by gill nets and drag nets. The fish yield potential, based on very scanty limnological data, has been estimated at 158 kg ha-1. The stocking rate for this reservoir has been arrived at (Jhingran, 1989) aiming a yield of 200 kg ha-1, which is the maximum taken out from the reservoir (1976–77). The absence of predator population, possibility of total harvesting, allochthonous enrichment, and high potential for stock maintenance above the natural carrying capacity of the system have been taken into consideration while fixing the target.

Table 10.10. Salient limno-chemical features of Chhaparwara reservoir
ParametersRANGEAVERAGE
SOIL QUALITY
pH7.80–8.658.40
Organic carbon (%)0.15–0.340.23
Available nitrogen (mg 100 g-1soil)33.60–61.6043.60
Available phosphorus (mg 100 g-1 soil)1.10–1.6013.40
Free carbon dioxide(%)12.00–14.5013.50
Spec. cond. (μmhos)120.00–900.00508.00
WATER QUALITY
pH8.00–8.408.30
Total alkalinity (mg 1-1)76.00–100.0088.00
Calcium (mg 1-1)20.00–35.0024.10
Magnesium (mg 1-1)8.00–12.0010.58
Total dissolved solids (mg 1-1)426.00–997.00535.00
Sp. conductivity (μmhos)567.00–690.00645.00
Dissolved organic matter (mg 1-1)7.57–13.279.10
Dissolved oxygen (mg 1-1)6.10–10.909.33
Chlorides (mg 1-1)70.00–136.00106.00
Fluorides (mg 1-1)tr–1.200.46
Phosphates (mg 1-1)0.11–0.16-
Nitrates (mg 1-1)0.40–1.100.84
Free ammonia (mg 1-1)0.09–0.110.10
Silicate (mg 1-1)1.92–8.004.17

tr=traces(After Jhingran, 1989b)

By adoption of annual cropping policy coupled with 8 to 9 months of growing period to enable stocked fish to attain average size of 500 g, it has been estimated that 600 fingerlings or 720 late fry ha-1 need to be stocked in the reservoir annually.

A total gill net area of 8 000 m2 would be required to harvest the targeted 200 kg ha-1. This fleet of net would need 15 to 40 fishermen and 7 to 20 boats, following the concept that 1 t catch per fisherman and 2 fishermen per boat would be most economic.

10.4 JAISAMAND RESERVOIR

Commissioned in 1730, Jaisamand is one of the oldest reservoirs in Rajasthan. The 7 286 ha reservoir has a catchment area of 1 813 km2 and a water holding capacity of 56.6 million m3. High values of specific conductivity (242 to 249 μmhos) indicate a high productivity. Nutrient enrichment in terms of phosphate (0.106 to 0.224 mg 1-1) and silicate (3.33 to 6.0 mg 1-1) is high and favourable for photosynthetic activities. Ranges in values of total alkalinity (54 to 91.5 mg 1-1) are also high (Sharma, 1980).

Despite an indiscriminate exploitation, with no closed season for a period of 240 years (till 1970), the reservoir continues to support a lucrative fishery (Durve and Kakkar, 1982). Durve (1976) reported 44 fish species, of which 23 contributed to commercial fisheries. Natural hybrids of catla × rohu and rohu × calbasu have been recorded.

Fishing is organised since 1949. Presently, the major commercial fish are major carps and mahseer (Catla catla, Labeo rohita, L. calbasu, L. fimbriatus, Cirrhinus mrigala, and Tor tor) minor carps (L. gonius, L. boggut, L. bata, Puntius sarana, Cirrhinus reba) catfishes (Wattago attu, Aorichthys seenghala, A. aor, Mystus cavasius, Heteropneustes fossilis and Ompok pabda), the murrels (Channa marulius, C. striatus, and C. punctatus) and the miscellaneous fish (Notopterus notopterus and Mastacembelus armatus). In the absence of a closed season, fishes are also caught in the course of spawning migration, which leads to considerable decline in the fish stock and their size at capture.

Table 10.11. Changes in species composition in Jaisamand reservoir
 19621963196419651969–70
Major carps(t)38239436822160
(59.94)(62.14)(61.42)(34.03)(17.63)
Catfishes and murrels Others (t)646162102279
(10.07)(9.56)10.38)(15.81)(82.37)
191179169326 
(29.99)(28.30)(28.20)(50.16) 
Total (t)637634599649339
Yield rate (kg ha-1)88.888.583.690.547.2
Fishing days 298283258243223

* Fig. in parenthesis indicate percentage (After Durve and Kakkar, 1982)

Fish catch during 1962 to 1965 was less than 600 t yr-1 (Table 10.11), when the average fishing days were about 270. In the early 1960s, Labeo rohita was dominant species, followed by Cirrhinus mrigala. Aorichthys seenghala and L. fimbriatus. Specimens of catla weighing as much as 39 kg were common till 1964, especially at the beginning of the fishing season in November and again at the onset of rains. Mahseer were few in number but the individual specimens weighed more than 3 kg. The major carps contributed up to 60% of the catch till 1964. Subsequently, the decline started as a consequence of continuous fishing of 223 days under contract system. The minor carps, chiefly L. gonius, came to dominate the catch. While catla was rarely encountered, the major carps which formed a minor component of the catch were represented byL. rohita, L. fimbriatus, L. calbasu and C. mrigala. All fishes including the catfishes were < 2 kg by weight. Fishing gear employed in the reservoir is mainly of three types, viz., surface gill nets, hook and line and drag nets.

10.5 OTHER RESERVOIRS

Fatehsagar

Fatehsagar, the oldest reservoir of Rajasthan, was constructed in 1678. It was reconstructed during the ninteenth centuary by the monarch, Maharana Fateh Singh, after whom it was named. It is surrounded by hills except on the eastern side, where a straight masonry dam of about 800 m is located. The reservoir lies on the northwest of Udaipur city at a latitude of 24° 35'N and longitude of 73°42'E.

The reservoir covers 400 ha at the full level of 587 m above MSL. The maximum length of the reservoir is 2.6 km and the maximum width 1.8 km. The length of shoreline is 8.5 km at FRL, the shoreline development index 1.2. Maximum and mean depths of the reservoir are 13.4 m and 3.0 m respectively. Catchment area of the river encompasses 53.66 km2 and the volume of reservoir at full level is 12.10 million m3. Sharma (1980) evaluated the limnochemical attributes of Fatehsagar. High ionic content, phosphorus loading and hardness indicate a high productivity.

Lakhotia lake

Situated near Pali City at 25°8'N, 73°3'E. Lakhotia is a rain-fed man-made lake, with a maximum length of 1 825 m and breadth of 950 m. Khatri (1984a) examined the limnological characteristics of water, rate of productivity and the biotic communities.

The reservoir has a maximum depth of 45 m and the water has a transparency from 51 to 105 cm. Bicarbonate alkalinity and the pH values register wide fluctuations (4 to 158 mg l-1 and 6.3 to 9.0 respectively), their higher values recorded in summer. A rich community of plankton develops during summer, taking advantage of the stable conditions and high concentrations of nutrients. The onset of monsoon disturbs the equillibrium and all the physico-chemical attributes fall short of optimum level, with a concomitant decrease in biotic communities. A recovery starts during winter as the water level stabilises.

Among micronutrients, Fe, Zn, and Mn are present in detectable concentrations throughout the year whereas Cu is present only during April to August (Khatri, 1984 b). A positive correlation between phytoplankton and phosphate and nitrate is reported by Khatri (1987b) along with an inverse relation between diatoms and silicates.

Outlines of physico-chemical and morphometric attributes in respect of Baghala, Namana, Anasagar, Mansarovar, Ranapratapsagar, Bandha Bharti, Gambhiri and Rajasamund are given by Sharma (1980), and reproduced in Table 10.12 together with data on other reservoirs of the State.

Table 10.12. Salient features of some reservoirs in Rajasthan
 BaghalaNamanaAnasagarFatehsagarChhaparwara
Date closure---16781894
Area (ha) at FRL100528-400200
Maximum length (km)---2.6-
Maximum width (km)---1.8-
Max depth (m)---13.4-
Mean depth (m)---3.01.70
Volume (million m3)686 Mft1875 Mft-12.101236.3
Catchment area (km2)261939.6-53.66515.2
Elevation (m above MSL)---587-
Shoreline (km)----8.5
Shore dev. index---1.20-
Volume dev. index---0.402-
Inflowing rivers---Mahshi-
Latitude (N)---24°35'26°37'
Longitude(E)---73°42'75°15'
Soil
Organic carbon (%)----0.15-0.34
Average nitrogen (mg 100g-1)----36.6-61.6
Average phosphorus (mg 100g-1)----1.1-1.6
Water
Water temperature (°C)21.2–25.520.5–26.221.8–24.215.9–30.111–31
pH8.1–8.58.58.57.4–9.28.0–8.4
Transparency (cm)78–141106–10751.5–74.049–115-
DO (mgl-1)6.8–7.38.03.5–8.54.7–14.86.1–10.9
CO2 (mgl-1)-2.0-0–8.80
Total alkalinity (mg l-1)112.5–13416.0–58.040.5–82.088.8–24076.0–100.0
Spec. cond. (μmhos)422.9–547.3379.3–472.7410.5–475.0255–541.1567–690
Total hardness (mg l-1)---31.6–157.6-
Calcium (mg l-1)12.4–15.210.7–18.07.2–11.28.8–2920–35
Nitrate (mg l-1)---0.009–0.50.4–1.10
Phosphate (mg l-1)0.34–0.3920.154–0.1630.192–0.262tr.-0.9290.11–0.16
Silicate (mg l-1)6.0–8.764.33–17.044.33–7.281.12–21.301.92–8.0
Chlorides (mg l-1)15–208–1614.0–15.07.3–38.770–136
Organic carbon (%)----7.57–13.27


Table 10.12 (cont.). Salient features of some reservoirs in Rajasthan
 RanapratapsagarBandh BhartiGambhiri
Area at FRL (ha)22000116002090
Volume (million m3)-76.4059.01
Mean depth (m)---
Catchment area (km2)27840205870
Water temperature (°C)22.5–26.721.7–26.623.6–26.2
pH8.0-8.67.8–8.57.9–8.5
Transparency (cm)239–347118–164132–152
Dissolved oxygen (mg-1)7.5–10.17.5-12.28.7–7.2
CO2(mg l-1)0-1.2Nil-0.50-2.5
Totalalkalinity (mg l-1)72–8361.3–7555–140
Spec.cond.(μmhos)239.4–248.5217.7–230.1106.7–136.8
Total hardness (mg l-1 )---
Calcium (mg l-1)14.2–20.010.2–13.39.5–13.4
Nitrate (mg l-1)---
Phosphate (mg l-1)0.134–0.1540.106–0.1260.126–0.267
Silicate (mg l-1)6.0–10.03.33–4.334.56–7.33
Chlorides (mg l-1)5.8–6.03.0–13.07.0–8.5


Table 10.12 (cont.). Salient features of some reservoirs in Rajasthan
 RamgarhJaisamandRajasamund
Date of closure19031730-
Area at FRL (ha)12607286950
Maximum length (km)7.0--
Maximum depth (m)18--
Mean depth (m)4.6--
Volume (million m3)59.056.6-
Catchment area (km2)7691813-
Elevation (m above MSL)132.54--
Length of shoreline (km)22.80--
Shore dev. index1.81--
Inflowing riversBangangaGomti, Jhameri 
  Rupar Begar 
Outflowing rivers Teri, Ghati 
Latitude (N)27°10'24°14'-
Longitude (E)75°32'73°57'-
Water temperature (°C)18–3222.0–23.921.5–26.0
pH8.3–8.68.5–8.97.8–8.3
Transparency (cm)80–10865–112108–189
DO (mg l-1)6.3–9.210.76.0–9.7
CO2 (mg l-1)0–1.50-
Total alkalinity (mg l-1)129–19854–91.567.5–111
Spec. cond. (μ mhos)307–791242–249427.3–897.6
Calcium (mg l-1)13.33–25.014.0–16.711.6–13.2
Nitrate (mg l-1)0.22–2.13--
Phosphates (mg l-1)tr.-0.40.106–0.2240.154–0.163
Silicate (mg l-1)5.6–18.463.33–6.03.300–13.33
Chlorides (mg l-1)38.66–76.06.0–8.010–12

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