1. There are three types of reservoirs in India - small (<1000 hectares), medium (1000-5000 hectares), and large (>5000 hectares). Small reservoirs account for the largest number (19,134) and area (1.48 million hectares). 2. Indian reservoirs tend to be nutrient-rich with narrow temperature fluctuations that prevent thermal stratification in many areas. Biotic communities include phytoplankton, zooplankton, fish, and decomposers like bacteria and fungi. 3. Fish production in Indian reservoirs is low on average at 20 kg/ha compared to potential yields, with room for improvement through management practices like stocking preferred fish species.

1. PRESENTED BY
Course Title – INLAND FISHERIES [FRM 501]
COURSE INSTRUCTOR
RESERVOIR FISHERIES
• Aadil Hussain • Dr. TASADUK HUSSAIN SHAH

2. Introduction
• Reservoir : Manmade impoundment created by obstructing the
surfaceflow, by erecting a dam of any description across a river, stream
or any water course.
• A reservoir usually mean a manmade lake created by using a dam or
barrage to store water.
• Reservoirs cover more than 1% of the land surface and created mainly
for irrigation, power generation etc.
• There are 19370 reservoirs in India covering an area of more than 3
million hectares.

4. classification
• There are three types of reservoirs
• Small
• Medium
• Large
SMALL RESERVIORS
 These reservoirs have an area of less than 1000 hectares.
 There no. in country is19134, covering an area of 1.48 million hectares.
 Tamil nadu has highest area and no. of small reservoirs with 8895 units followed
Karnataka & Andhra pradesh.

5. MEDIUM RESERVIORS
• Area between 1000 – 5000 hectares.
• 180 units in country, covering an area of 0.507 million ha.
• Madhya pradesh has highest area of these reservoirs but
Andhra pradesh has highest no. of medium reservoirs “32”

6. Large reservoirs
• Area beyond 5000 ha.
• 56 in number covering an area of 1.60 million ha.
• Karnataka has max. no. “12” but Andhra pradesh has max.
area of these reservoirs

7. Large Reservoirs in India
• Nagarjuna Sagar – Andhra
Pradesh
• Srisailam – Andhra Pradesh
• Somasila – Andhra Pradesh
• Gobind Sagar – Himachal
Pradesh
• Maharana Pratap Sagar –
Himachal Pradesh
• Stanley Reservoir – Tamil
Nadu
• Shanti Sagara – Karnataka
• Minimata Hasdeo Bango –
Chhattisgarh

8. Limnology profile of Indian reservoirs
• Nutrient rich
• Peninsular reservoirs have narrow range of air and water temp.
fluctuations during dif. Seasons. A phenomenon which prevents
thermal stratification.
• Reservoirs in upper peninsula undergo stratification during
summer, but wind induces turbulence facilitating the availability
of nutrients at trophogenic zone.
• Reservoirs of Western Ghats and Northeast are oligotrophic due
to poor nutrient status of catchment soil.

9. Biotic community of reservoirs
• Heavy discharge retards the growth of macrophytic vegetation.
• Rich plankton community is the hall mark of Indian reservoirs
• Blue-green algae form main stage of plankton community.
• Overwhelming presence of cyanobacteria “microcystis
aeruginosa” in Indian reservoirs is remarkable.

10. CONTINUED…
• Rocky bottom and water level fluctuations adversely affect
benthic community.
• Icthyofauna of reservoir represent the fauna of parent river
system.
• At the time of impoundment fish diversity suffer a setback as
lotic habitat transfers into lentic.
• Many species perish and a few adopt to changed situation.

11. • However Indian reservoirs have rich variety of fish species.
• Large reservoirs harbor 60 species of fishes.
• Common fish species are :-
 IMcs “Labio Rohita, L. Calbasu, L. Fimbriatus, C. Mirgala, Catla Catla”
 Mahseers “Tortor, T. putitora, T. khudree, Neolissochilus hexagonolepis”
 Minor carps “Cirrhinus cirrhosa, C. reba, Labeo kontius, L. bata, Puntius
sarana, Schizothorax richardsonii”
 Catfishes “Sperato sheengala, Wallago attu, Pangasius etc.”
 Featherbacks “Notopterus notopterus, Notopterus chitala”
 Murrels “Channa marulius, C. stratus, C. punctatus, C. gaucha”
 Exotic fishes “Oreochromus mossumbicus, Hypophthalmicthysmolitrix, Cyprinus
carpio communis, C. specularis, Gambusia affins, Ctenopharyngodon idella.
CONTINUED…

12. Impact of reservoir formation on the native Ichthyofauna
Formation of reservoirs have affected especially the following Indigenous
fish stocks:
The mahseers, snow trouts and Labeo dero and L dyocheilus of the Himalayan
streams.
The anadromous hilsa, the catadromous eels,and freshwater prawns of all
major river systems.
P. sarana, T. tor,Tor mahanadtcus, T. mosal, L.fimbrtatus, L calbasu,and Rhinomugil
corsula of the Mahanadi river.
P. dobsoni, P. dubius, P. carnaticus, and Labeo kontius of the Cauvery basin.
P. kolus, P. dubius, P. sarana, P. porcellus, L.fimbrtatus, L. calbasu, L. pangusia and
Tor kudree of the Krishna river system, and
The mahseers, eels and Osteobrama belangiri of the northeast

13. DETERMINANTS OF PRODUCTIVITY
• The factors determining the productivity of reservoirs are classified into :-
A. morphometric factors
B. Climatic factors
C. Edaphic factors
A. Morphometric factors
a) Depth :- Shallow lakes are more productive.
b) Shore development :- Higher the degree of irregularity in the shore, higher is the
production.
c) Fluctuation in water level:- All the biotic communities are at their lowest ebb
during max. level fluctuation.

14. B. Climatic factors
• Latitude is the most imp. Factor which plays an imp. role In determining the
magnitude of solar energy and air temp.
• In south India fluctuation in air and water temperature is narrow which
prevents formation of thermocline.
• During thermal stratification nutrients get locked up at the bottom.
• When stratification occurs its early breaking is necessary for good production
• Wind induces turbulence during monsoon usually breaks thermocline in Indian
reservoirs.

15. CONTINUED…
• The rainfall at catchment area is also very imp. than rainfall at reservoir
because soil status of catchment area defines the nutrient status of
reservoir.
Thus in many reservoirs inspite of poor soil quality
of basin the productivity is high by virtue of
Alloichthonous nutrients.

16. C. Edaphic factors
• Physiochemical properties of soil and water are the major determinants of
productivity of reservoir.
• Poor light penetration due to suspended silt and clay retards production but
poor visibility due to plankton bloom is +ve index of production.
• D.O > 5 ppm
• Ph < 8 ppm
• Alkalinity > 50 ppm
• Hardness > 70 ppm
Indicators of better
production

17. Formation
• A reservoir passes through three distinct phases after its formation viz.
I. Initial high fertility phase
II. Trophic depression phase
III. Final fertility phase
i. Initial high fertility phase
 A newly formed reservoir floods vast area , causing decay of submerged
vegetation.
 Nutrients release, causing Initial high fertility phase.
 Fish food organisms develop. (plankton, bottom microflora and fauna.)
 Lasts for 2-3 years.

19. II. Trophic depression phase
• Characterized by rapid utilization of nutrients by flora and
release of nutrients from reservoir bed due to sedimentation.
• Low production of fish food organisms & low fish growth.
• This stage exists for shorter duration.

20. III. FINAL FERTILITY PHASE
• A reservoir gradually recovers with accumulation of
nutrients.
• It lasts for 1-1.5 years.
• In Indian reservoirs this phase would be much higher in
magnitude than initial and reservoir production increases after
ageing.

21. Trophic dynamics
• The aquatic ecosystem consists of :-
 producers – autotrophs
 Primary consumers – zooplankton & some fishes.
 Secondary consumers –insect larvae, fishes etc.
 Tertiary consumers – large predators or top carnivores.
 Decomposers – bacteria, fungi.
• During energy transformation the efficiency of energy conversion is
reduced to a tenth from one trophic level to another.

22. Energy flow
 Energy flow and nutrient cycle are two important principles of
ecosystem.
 Productivity of a lake depends on capacity to transform solar energy
into chemical energy.
 The studies conducted in Bhavanisagar, nagarjunsagar, Rihand and
gobindsagar reservoirs have shown that photosynthetic efficiency was
high in productive reservoirs like Bhavanisagar (0.412), Nagarjunsagar
(0.290) and Gobindsagar (0.692). But it is interesting to note that energy
harvest as fish was much low in Nagarjunsagar (0.055) as compared to
Bhavanisagar (0.290), which showed that management failed to harvest
fish from Nagarjunsagar though it was productive.

23. CONTINUED…
• In an ecosystem the biological output or production of harvestable
organisms can be at various trophic levels.
 Under a grazing food chain :-
• Phytoplankton > zooplankton > minnows > catfishes. (or)
• Phytoplankton > zooplankton > fish
System prevails.
• Shortening the food chain will lead to higher rates of fish production.
But in reservoir management there is little scope for changing
community structure of plankton to increase production. However
alteration in species spectrum of fish may be done and for this only
stocking of fish is a successful tool in management.

24. Fish production trends and potential
• Fish yield from Indian reservoirs is poor varying from 0.05 kg/ha in
Bihar to 35.5 kg/ha in himachal pradesh with national average of 20
kg/ha.
• The average national yield from small reservoirs is 50 kg/ha which is
well below the rates achieved in China as 800 kg/ha, 300 kg/ha in
Srilanka & 100 kg/ha in Cuba.

25. Actual and potential production from categories of reservoirs in
India
Area (ha)
Present
production
(tonnes)
Potential
production
(tonnes)
Small 1485557 74200 743000
Medium 507295 6500 127000
Large 1160511 13000 116000
Total 3153366 93700 986000

26. CONTINUED…
• There are 19370 reservoirs in country with average production rate of
50 kg/ha, 12kg/ha, 11kg/ha from small, medium and large reservoirs
against the potential of 500, 250 and 100kg/ha respectively.
• Present production from all reservoirs in country is 93700 tonnes
against the potential of 1 million tonnes.

27. years Production (t) years Production (t) years Production (t)
1960-61 417 1966-67 291 1972-73 276
1961-62 358 1967-68 357 1973-74 555
1962-63 431 1968-69 354 1974-75 321
1963-64 408 1969-70 230 1975-76 304
1964-65 223 1970-71 260 1976-77 533
1965-66 311 1971-72 254
YEARLY TOTAL LANDINGS FOR THE
PERIOD 1960-1961 TO 1976-1977