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Chapter - 6
ICHTHYOFAUNA OF IDUKKI RESERVOIR
6.1 Introduction
6.2 Materials and Methods
6.3 Results
6.4 Dis cussion
6.1 Introduction
India is one of the mega biodiversity countries in the world and
occupies the ninth position in terms of freshwater mega biodiversity
(Mittermeier and Mittermeier, 1997). Biodiversity is essential for stabilization
of ecosystem protection of overall environmental quality for understanding
intrinsic worth of all species on the earth (Ehrlich and Wilson, 1991).
Ichthyodiversity refers to variety of fish species; depending on contest and
scale, it could refer to alleles or genotypes within fish population, to species of
life forms within a fish community and to species or life forms across aqua
regimes (Burton et al., 1992). In India there are 2500 species of fishes of
which 930 live in freshwater and 1570 are marine (Kar, 2003). Indian
reservoirs preserve a relatively rich variety of fish species. The present
reservoir area of India is about 50% of total reservoir area in Southeast Asia.
However, despite having such a vast resource, the majority of these reservoirs
are not being scientifically managed for fisheries. Due to this reason, the per
Chapter 6
200 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
hectare fish production of Indian reservoirs is very poor (Desai and Srivastava,
2004). The fish yield from Indian reservoirs is rather very 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 in India is nearly
50 kg/ha, which is well below the rates achieved in many other countries such
as >800 kg/ha in China, 300 kg/ha in Sri Lanka and 100 kg/ha in Cuba
(Sugunan, 2011).
Although, among the maritime states of India, Kerala occupies
foremost position in marine fish production, accounting for over 20% of the
total landings in the country, contribution to inland fish production is only
negligible (2.20%) and this is primarily due to the inadequate attention
received by this sector (Padmakumar et al., 2008). According to Inland Fish
Statistics (2006) in the year 2005-2006, the marine fish production from
Kerala was 5.59 lakh tonnes where as the inland fish production was only 0.78
lakh tonnes. Owing to manageable size, all the reservoirs in Kerala are
logistically suitable for fish production. Despite the existence of many such
small and medium reservoirs in the state, efforts to develop them on scientific
lines for fish production are wanting. Although the average yield in the
managed reservoirs is 23.38 kg/ha, the average per ha yield of the total
reservoir area in the state is only 5 kg/ha. This is primarily due to the
inadequate attention received by the inland fisheries sector during the early
years of the state’s planned development, as the Keralites have a marked bias
in favour of marine fish. During the last few decades, due to improved
facilities for processing, storage and transport, marine fish has become
available to consumers all over the state, resulting in a shortage. Thus the
people have turned towards the inland fish and they even developed a taste for
it. Catla, rohu, mrigal and even common carp are no longer at a discount, in
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 201
comparison to sardines and mackerals. Now, the state has recognized the
importance of inland fisheries and fresh water aquaculture. However a perusal
of literature indicates that no major initiative has been taken to create a
database on the ecosystem functions and production potential of reservoir in
the state. Very little information is available on their water quality and biotic
communities (Padmakumar et al., 2008).
Fishes are among the most important natural resources of the country
and provide considerable support in the nation’s economic growth. Fishes are
not only important for solving the food problem by providing mineral enriched
animal protein but the fishes are also important for their ornamental and
recreational value. Many by-products of industrial value are also derived from
fishes. Several bio-active compounds, extracted from the fishery resources add
to their importance in the field of medical science. It provides employment to
lakhs of people in fields of capture and culture fishery, ornamental fish trade,
sport fishery, export and import of fishes. Fishes are natural source for the
biological control of mosquitoes and other harmful aquatic insects. Many
canning industries and export houses are dependent on Indian fisheries.
Fishery industry plays a significant role in providing protein food,
employment generation for rural people and earning foreign exchange for the
country.
Fish assemblages in lakes and reservoirs are greatly influenced by
water quality parameters (Carol et al., 2006). Contamination of water bodies
might lead to a change in their trophic status and render them unsuitable for
aquaculture. Several physico-chemical or biological factors could act as stress
and adversely affect fish growth and reproduction (Iwama et al., 2000).
Plankton communities in any aquatic ecosystem determine its trophic status.
The planktonic organisms in aquatic systems are essentially linked in the food
Chapter 6
202 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
chain and play an important role in transformation of energy from one tropic
level to the next highest, ultimately leading to fish production, which is the
final product of the aquatic environment. Hence regular monitoring of
physico-chemical and biological water quality parameters is essential to
determine status of water bodies with reference to fish culture.
The environmental conditions in reservoirs are intermediate between
those of rivers and lakes. These differences are reflected in the morphology,
hydrology, physico-chemical and biological characteristics (Li, 2001).
Although ichthyofauna of a reservoir basically represents the fauna of the
parent river system, fish species diversity usually suffers a setback on
impoundment (Jhingran, 1990). Several studies reported the effects of
damming on the Icthyofauna (Fernando and Holcick, 1991; Beaumord, 1991;
Duncan and Kubecka, 1995). Some of the workers mentioned damming create
a insurmountable barrier for any fish species, isolating sites and specific zones
that otherwise would be routinely used for feeding or reproduction ( Beaumord
and Petrere, 1994; Agostinho and Zalewski, 1996) and they suggested this
isolation by damming can make a genetic effect on fish population also (
Petrere,1996).
Considerable studies on fish diversity from reservoirs and lakes in
India have been carried out during the last few decades (Sreenivasan, 1984;
Valsangakar, 1987; Sugunan and Yadava, 1991; Devi, 1997; Kar and Dey
2000; Chandrasekhar, 2003; Sakhare and Joshi, 2004; Desai and Srivastava,
2004; Venkateshwarlu et al., 2005; Pawar et al., 2006; Sharma, 2007;
Srinivas, 2007; Negi, 2008; Rao et al., 2011). However not much study has
been conducted so far in Idukki reservoir in Kerala though it is the largest
reservoir in the State except a preliminary study conducted by Gopinath and
Jayachandran (1984) and Nair (1988). Therefore this study is aimed to
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 203
document the fish resources and its diversity in the Idukki reservoir in Kerala,
India.
6.2 Materials and Methods
Materials and methods are explained in detail under chapter 2.
6.3 Result
6.3.1 Species composition
The fish fauna of the Idukki reservoir was analyzed by collecting samples
bimonthly from pre determined 16 stations during three seasons (premonsoon,
monsoon and postmonsoon). A total number of 5800 fishes, weighing 1266.76 kg
were caught during the three years of study (Fig. 6.1 and 6.2).
Fig.6.1 Total number of fish obtained from Idukki reservoir
The fish were identified, calculated the abundance, biomass and
diversity indices at each stations and in all seasons. The species composition
0
200
400
600
800
1000
1200
Num
ber o
f in
divi
dual
s
Chapter 6
204 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
obtained from the reservoir is given in Table 6.1. In the present study, a total
of 19 species of fish belonging to 18 genera, 11 families and 6 orders were
recorded in the reservoir. Cypriniformes, Siluriformes, Atheriniformes,
Perciformes, Channiformes and Mastacembeliformes were the 6 orders and in
which Siluriformes was represented by 4 families, Cypriniformes and
Perciformes were comprised of 2 families each, whereas other orders were
represented by single family each. The family Cyprinidae was found to be the
most diverse, represented by 9 species and the remaining families were
represented by a single species each. The fish recorded from the Idukki
reservoir were Aplocheilus lineatus, Barilius bakeri, Catla catla, Channa
gachua, Cirrhinus cirrhosa, Clarias batrachus, Cyprinus carpio,
Heteropneustis fossilis, Labeo rohita, Mastacembelus guentheri, Mystus
vittatus, Nemacheilus rupecola, Ompok bimaculatus, Oreochromis
mossambicus, Parambassis dayi, Puntius melanampyx, Puntius vittatus,
Rasbora daniconius and Tor khudree.
Fig.6.2 Total catch of fis h recorded from Idukki reservoir
0
50
100
150
200
250
300
350
400
450
Biom
ass (
kg)
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 205
In the total number of fish collected during the study period, family
Cyprinidae was dominated by contributing 43.36% of the total fish followed
by Siluridae (20.05%), Cichlidae (7.62%), Channidae, (6.90%), Bagridae
(5.22%), Mastacembelidae (4.88%), Cyprinodontidae (4.60%), Cobitidae
(3.79%), Ambassidae (3.34%) whereas family Heteropneustidae and Clariidae
registered only 0.14% and 0.09% respectively (Fig. 6.3).
Table 6.1 Fish species recorded from Idukki Reservoir
Order Family Species Local Name
1.Cypriniformes 1.Cyprinidae 1.Barilius bakeri Thuppalkothi
2.Rasbora daniconius Kallemutty
3.Cirrhinus cirrhosa Kooral
4.Cyprinus carpio Katti
5.Catla catla Catla
6.Labeo rohita Rohu
7.Puntius melanampyx Vazhakavarayan
8.Puntius vittatus Karingana/Kananjon
9.Tor khudree Yeru
2.Cobitidae 10.Nemacheilus rupecola Kalamparanda
2.Siluriformes 3.Bagridae 11.Mystus vittatus Chillan Koori
4.Siluridae 12.Ompok bimaculatus Chottavala
5.Clariidae 13.Clarias batrachus Mushi
6.Heteropneustidae 14.Heteropneustis fossilis Kaari
3.Atheriniformes 7.Cyprinodontidae 15.Aplocheilus lineatus Nettipotan
4.Perciformes 8.Cichlidae 16.Oreochromis mossambicus Tilapia
9.Ambassidae 17.Parambassis dayi Chillumeen
5.Channiformes 10.Channidae 18.Channa gachua Cherumeen
6.Mastacembeliformes 11.Mastacembelidae 19.Mastacembelus guentheri Aaron
Chapter 6
206 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
Fig. 6.3 Familywise percentage composition of fish abundance (total) from Idukki reservoir
6.3.2 Abundance and biomass
The average number of fish (abundance) obtained from the reservoir
during the 3 years of study showed that the species Ompok bimaculatus
recorded the highest catch with the number of 387/year, followed by Cirrhinus
cirrhosa with number 355/year and Oreochromis mossambicus with the
average number of 148/year (Fig.6.4). The species Ompok bimaculatus also
predominated as per relative abundance (20.05%) followed by Cirrhinus
cirrhosa (18.34%) and Oreochromis mossambicus (7.62%) (Fig.6.5).
Fig. 6.6 shows the average of total biomass (weight) of fish obtained
during the study period. In Idukki reservoir, Channa Gachua recorded the
highest landings of 143.91 kg/year during the three years of study and it was
followed by Tor khudree (81.66 kg/year) and Cyprinus carpio (69.04 kg/year).
The relative biomass of Channa Gachua, Tor khudree and Cyprinus carpio
was 34.08%, 19.34% and 16.35% respectively (Fig. 6.7).
4.60 %
43.36 %
6.90 %
0.09 %0.14 %
4.88 %
5.22 %
3.79 %
20.05 %
7.62 % 3.34 %
Cyprinodontidae
Cyprinidae
Channidae
Clariidae
Heteropneustidae
Mastacembelidae
Bagridae
Cobitidae
Siluridae
Cichlidae
Ambassidae
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 207
Fig.6.4 Total number of fish obtained (mean) from Idukki reservoir
Fig. 6.5 Specieswise relative abundance of fish obtained (mean) from Idukki reservoir
0
50
100
150
200
250
300
350
40089
72
2
133
355
2
42
3 8
94 101
73
387
148
65
106
69 73
111
Num
ber o
f in
divi
dual
s (m
ean)
4.60 % 3.74 % 0.10 %6.90 %
18.34 %
0.09 %
2.19 %
0.14 %
0.43 %4.88 %5.22 %
3.79 %
20.05 %
7.62 %
3.34 %5.48 %
3.57 %3.76 % 5.74 %
A. lineatus B. bakeri C.catla C. gachua C. cirrhosa
C. batrachus C. carpio H. fossilis L. rohita M. guentheri
M. vittatus N. rupecola O.bimaculatus O.mossambicus P. dayi
P.melanampyx P.vittatus R. daniconius T. khudree
Chapter 6
208 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
Fig.6.6 Total biomass (mean) of fis h recorded from Idukki reservoir
Fig. 6.7 Relative biomass of fish recorded from Idukki reservoir
0
20
40
60
80
100
120
140
160
0.63
0.44 5.
65
143.
91
31.6
1
0.36
69.0
4
0.17
21.1
6
19.6
1
0.74
0.32
34.9
3
10.6
1
0.26
0.39
0.32
0.45
81.6
6
Biom
ass (
mea
n) in
kg
0.15 %
0.10 %
1.34 %
34.08 %
7.49 %0.08 %
16.35 %0.04 %
5.01 %4.64 %
0.17 %0.07 %
8.27 %
2.51 %0.06 %0.09 %
0.08 %0.11 % 19.34 %
A. lineatusB. bakeriC.catlaC. gachuaC. cirrhosaC. batrachusC. carpio H. fossilisL. rohitaM. guentheriM. vittatusN. rupecolaO.bimaculatusO.mossambicusP. dayiP.melanampyxP.vittatus R. daniconiusT. khudree
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 209
6.3.3 Seasonal variations in fish abundance
ANOVA showed significant variation while comparing the mean
abundance of fish obtained in different seasons (P < 0.05) but insignificant
among stations (P > 0.05) (Appendix IV, Table 1). Premonsoon season
recorded highest abundance of fish with the number of 863 followed by
postmonsoon (613 nos) and the lower abundance was registered in monsoon
(458 nos) (Table 6.2).
During premonsoon season, 16 species were recorded from the reservoir.
Catla catla, Clarias batrachus and Labeo rohita were not obtained in this season
(Table 6.2). Ompok bimaculatus was the most dominant species with the number
of 225 followed by Cirrhinus cirrhosa (181nos) and Oreochromis mossambicus
(81nos). Among stations, the highest average abundance of Ompok
bimaculatus (22 nos) was noticed at station 11 whereas the lowest (9 nos) at
station 8. Station 10 recorded the highest abundance of Cirrhinus cirrhosa (18
nos) and station 14 recorded the lowest (6 nos). The abundance of
Oreochromis mossambicus was observed high (8 nos) at stations 13 and 14
whereas low (2 nos) at station 10 (Fig. 6.8).
During monsoon season all species except Heteropneustis fossilis were
observed in the reservoir (Table 6.2). In this season also, Ompok bimaculatus
was the most dominant species in the reservoir with the number of 66 followed
by Channa gachua (62nos) and Tor Khudree (50nos). Among stations, the
highest average abundance of Ompok bimaculatus (7nos) was observed at
station 15 and lowest (3nos) at stations 1, 3, 8, 13 and 16. Channa gachua was
recorded with 7 numbers at station 6 and low (2) at stations 1 and 11. The
highest abundance of Tor Khudree (5nos) was recorded at station 6 while the
low (2 nos) was noticed at stations 2, 3 and 11(Fig.6.9).
Chapter 6
210 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
Fig.6.8 Abundance (mean) of fish recorded during premonsoon seas on at various stations from Idukki reservoir
Fig.6.9 Abundance (mean) of fis h recorded during mons oon season at various stations
from Idukki reservoir
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Abun
danc
e (m
ean)
A. lineatus B. bakeri C. catla C. gachua C. cirrhosa
C. batrachus C. carpio H. fossilis L. rohita M. guentheri
M. vittatus N. rupecola O. bimaculatus O. mossambicus P. dayi
P. melanampyx P. vittatus R. daniconius T. khudree
0
5
10
15
20
25
30
35
40
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Abun
danc
e (m
ean)
A. lineatus B. bakeri C. catla C. gachua C. cirrhosa
C. batrachus C. carpio H. fossilis L. rohita M. guentheri
M. vittatus N. rupecola O. bimaculatus O. mossambicus P. dayi
P. melanampyx P. vittatus R. daniconius T. khudree
Stations
Stations
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 211
Table 6.2 Seasonal variation on fish abundance (mean) recorded from Idukki reservoir (Nos)
Species Premonsoon Monsoon Post monsoon Aplocheilus lineatus 34.00 17.00 38.00
Barilius bakeri 28.00 19.00 25.00
Catla catla 0.00 2.00 0.00
Channa gachua 40.00 62.00 32.00
Cirrhinus cirrhosa 181.00 49.00 125.00
Clarias batrachus 0.00 2.00 0.00
Cyprinus carpio 10.00 20.00 12.00
Heteropneustis fossilis 2.00 0.00 1.00
Labeo rohita 0.00 7.00 1.00
Mastacembelus guentheri 40.00 23.00 31.00
Mystus vittatus 40.00 21.00 40.00
Nemacheilus rupecola 27.00 19.00 27.00
Ompok bimaculatus 225.00 66.00 96.00
Oreochromis mossambicus 81.00 33.00 34.00
Parambassis dayi 25.00 15.00 25.00
Puntius melanampyx 51.00 17.00 38.00
Puntius vittatus 23.00 20.00 26.00
Rasbora daniconius 31.00 16.00 26.00
Tor khudree 25.00 50.00 36.00
Total 863.00 458.00 613.00
Percentage contribution 44.62% 23.68% 31.70%
During postmonsoon season, Cirrhinus cirrhosa was the most abundant
species with the average number of 125 followed by Ompok bimaculatus (96 nos)
and Mystus vittatus (40 nos) (Table 6.2). Catla catla and Clarias batrachus were
not recorded during postmonsoon season in the reservoir. Among stations, the
highest average abundance of Cirrhinus cirrhosa (11nos) was recorded at
stations 4 and 13 whereas the lowest value (5 nos) recorded at stations 1, 10
and 16. Station 12 recorded the high abundance (9 nos) of Ompok bimaculatus
Chapter 6
212 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
and station 16 represented the low abundance (4nos). Mystus vittatus was
recorded high (5nos) at stations 12 and 15 whereas low (1nos) at stations 1, 2,
4 and 7 (Fig. 6.10).
Fig.6.10 Abundance (mean) of fish recorded during postmonsoon s eason at various stations
from Idukki reservoir
While comparing the relative abundance of fish obtained in different
seasons, premonsoon season contributed 44.62% of the total fish catch
followed by postmonsoon (31.70%) and monsoon season recorded the lowest
(23.68%) (Table 6.2). During premonsoon, Ompok bimaculatus recorded the
highest value of 26.09% followed by Cirrhinus cirrhosa (20.96%) and
Oreochromis mossambicus (9.38%) (Fig.6.11). In monsoon season also
Ompok bimaculatus registered with the highest relative abundance of 14.43%
followed by Channa gachua with 13.48% and Tor Khudree with 10.86%
(Fig.6.12). During postmonsoon season Cirrhinus cirrhosa recorded the
0
5
10
15
20
25
30
35
40
45
50
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Abun
danc
e (m
ean)
A. lineatus B. bakeri C. catla C. gachua C. cirrhosa
C. batrachus C. carpio H. fossilis L. rohita M. guentheri
M. vittatus N. rupecola O. bimaculatus O. mossambicus P. dayi
P. melanampyx P. vittatus R. daniconius T. khudree
Stations
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 213
highest relative abundance of 20.36% overriding Ompok bimaculatus
(15.73%) and Mystus vittatus (6.59%) (Fig.6.13).
Fig.6.11 Relative abundance of fish obtained during premonsoon season from Idukki reservoir
Fig.6.12 Relative abundance of fish obtained during monsoon season from Idukki reservoir
3.94 %3.28 %
4.63 %
20.96 %
1.16 %
0.27 %
4.63 %4.63 %
3.13 %26.09 %
9.38 %
2.89 %5.91 %
2.66 %3.55 %
2.89 %
A. lineatusB. bakeriC. gachuaC. cirrhosaC. carpio H. fossilisM. guentheriM. vittatusN. rupecolaO.bimaculatusO.mossambicusP. dayiP.melanampyxP.vittatus R. daniconiusT. khudree
3.79 % 4.08 %0.44 %
13.48 %
10.71 %
0.36 %4.37 %
1.53 %5.10 %
4.52 %4.23 %
14.43 %
7.14 %
3.28 %3.79 %
4.37 %3.50 %
10.86 %
A. lineatusB. bakeriC.catlaC. gachuaC. cirrhosaC. batrachusC. carpio L. rohitaM. guentheriM. vittatusN. rupecolaO.bimaculatusO.mossambicusP. dayiP.melanampyxP.vittatus R. daniconiusT. khudree
Chapter 6
214 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
Fig.6.13 Relative abundance of fish obtained during postmonsoon s eason from Idukki reservoir
6.3.4 Seasonal variations in fish biomass
ANOVA of mean biomass showed significant variation among seasons
(P < 0.05) whereas no significant variation recorded among stations (P > 0.05)
(Appendix IV, Table 2). Monsoon season recorded the highest biomass
whereas premonsoon and postmonsoon seasons showed similarity in the
biomass obtained (Table 6.3). During premonsoon season, Channa gachua
registered the highest biomass of 33.16 kg which was followed by Ompok
bimaculatus (19.81 kg) and Cirrhinus cirrhosa (17.34 kg) (Table 6.3). Among
stations, highest average biomass of Channa gachua (4.03 kg) was noticed at
station 14 and lowest (0.96 kg) at station 6 in this season. In the case of
Ompok bimaculatus, stations 11 and 12 recorded the highest biomass (1.81 kg)
whereas station 6 recorded the lowest value of 0.76 kg. The biomass of
Cirrhinus cirrhosa was observed high (1.94 kg) at station 10 while the lowest
biomass (0.45 kg) was noted at station 14 (Fig. 6.14).
6.15 %4.14 %
5.17 %
20.36 %
2.01 %
0.05 %
0.22 %
5.06 %6.59 %4.41 %
15.73 %
5.50 %
4.03 %
6.15 %4.25 %
4.25 %5.93 %
A. lineatusB. bakeriC. gachuaC. cirrhosaC. carpio H. fossilisL. rohitaM. guentheriM. vittatusN. rupecolaO.bimaculatusO.mossambicusP. dayiP.melanampyxP.vittatus R. daniconiusT. khudree
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 215
Table 6.3 Seasonal variation on fish biomass (mean) recorded from Idukki reservoir (Kg)
Species Premonsoon Monsoon Postmonsoon
Aplocheilus lineatus 0.26 0.12 0.24 Barilius bakeri 0.18 0.11 0.15 Catla catla 0.00 5.65 0.00 Channa gachua 33.16 80.47 30.28 Cirrhinus cirrhosa 17.34 5.19 9.09
Clarias batrachus 0.00 0.36 0.00 Cyprinus carpio 14.41 38.10 16.53 Heteropneustis fossilis 0.15 0.00 0.02 Labeo rohita 0.00 18.86 2.30 Mastacembelus guentheri 8.91 4.74 5.95 Mystus vittatus 0.27 0.15 0.31 Nemacheilus rupecola 0.13 0.08 0.11 Ompok bimaculatus 19.81 5.93 9.19 Oreochromis mossambicus 5.70 2.38 2.53 Parambassis dayi 0.10 0.06 0.10 Puntius melanampyx 0.20 0.06 0.13
Puntius vittatus 0.10 0.08 0.14 Rasbora daniconius 0.20 0.09 0.16 Tor khudree 15.03 42.08 24.55 Total 115.96 204.51 101.79 Percentage contribution 27.46% 48.43% 24.11%
During monsoon season, Channa gachua recorded the highest biomass
of 80.47 kg followed by Tor Khudree (42.08 kg) and Cyprinus carpio (38.10
kg) (Table 6.3). Among stations, the highest average biomass of Channa
gachua (8.53 kg) was observed at station 6 and the lowest (2.22 kg) at station
11. Tor Khudree was also recorded highest average biomass (5.61 kg) at
station 6 whereas the lowest value (0.90 kg) observed at station 11. In the case
of Cyprinus carpio, highest biomass (4.07 kg) was observed at station 14 and
lowest (0.92 kg) at station 1 (Fig. 6.15).
Chapter 6
216 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
Fig.6.14 Biomass (mean) of fish recorded during premons oon seas on at various stations
from Idukki reservoir
Fig.6.15 Biomass (mean) of fish recorded during monsoon season at various stations from Idukki
reservoir
0.00
1.002.00
3.004.00
5.00
6.007.00
8.009.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
A. lineatus B. bakeri C. catla C. gachuaC. cirrhosa C. batrachus C. carpio H. fossilisL. rohita M. guentheri M. vittatus N. rupecolaO. bimaculatus O. mossambicus P. dayi P. melanampyxP. vittatus R. daniconius T. khudree
0.00
5.00
10.00
15.00
20.00
25.00
30.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
A. lineatus B. bakeri C. catla C. gachua C. cirrhosa
C. batrachus C. carpio H. fossilis L. rohita M. guentheri
M. vittatus N. rupecola O. bimaculatus O. mossambicus P. dayi
P. melanampyx P. vittatus R. daniconius T. khudree
Stations
Bioma
ss (m
ean)
Bioma
ss (m
ean)
Stations
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 217
In postmonsoon season, Channa gachua recorded the highest biomass
with a total weight of 30.28 kg.The next dominant species in this season as per
biomass was Tor Khudree (24.55 kg) followed by Cyprinus carpio (16.53 kg)
(Table 6.3). Among stations, station 7 recorded the highest average biomass of
Channa gachua (3.23 kg) and the lowest (0.40 kg) was noticed at station 13.
The highest biomass of Tor Khudree (3.02 kg) and Cyprinus carpio (2.70 kg)
were observed at stations 7 and 6 respectively whereas the lowest biomass of
Tor Khudree (0.46 kg) and Cyprinus carpio (0.02 kg) were recorded at
stations 9 and 1 respectively (Fig. 6.16).
Fig.6.16 Biomass (mean) of fish recorded during postmonsoon season at various stations from Idukki reservoir
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
A. lineatus B. bakeri C. catla C. gachuaC. cirrhosa C. batrachus C. carpio H. fossilisL. rohita M. guentheri M. vittatus N. rupecolaO. bimaculatus O. mossambicus P. dayi P. melanampyxP. vittatus R. daniconius T. khudree
Stations
Bioma
ss (m
ean)
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218 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
While comparing the relative biomass of fish obtained in the three
seasons, monsoon season recorded the higher value (48.43%) followed by
premonsoon with 27.46% while the postmonsoon recorded 24.11% (Table
6.3). During premonsoon season, Channa gachua registered the highest
relative biomass in the reservoir with 28.60 %. Ompok bimaculatus and
Cirrhinus cirrhosa were contributed relative biomass of 17.09% and 14.95%
respectively in the premonsoon season (Fig.6.17). During monsoon season, the
species Channa gachua, Tor Khudree and Cyprinus carpio contributed
predominantly to the biomass than any other species where the Channa
gachua obtained the highest value of 39.35%. The species Tor Khudree and
Cyprinus carpio were constituted 20.58% and 18.63% respectively of the total
relative biomass (Fig.6.18) in this season. In postmonsoon season also Channa
gachua recorded the highest relative biomass in the reservoir with 29.75 %
followed by Tor Khudree (24.12%) and Cyprinus carpio (16.24%) (Fig. 6.19).
Fig.6.17 Relative biomass of fish recorded during premonsoon season from Idukki reservoir
0.23 %0.15 %
28.60 %
14.95 %
12.43 %0.13 %
7.69 %
0.24 %
0.11 %
17.09 %
4.91 %0.09 %
0.17 %
0.08 %
0.17 % 12.96A. lineatusB. bakeriC. gachuaC. cirrhosaC. carpio H. fossilisM. guentheriM. vittatusN. rupecolaO.bimaculatusO.mossambicusP. dayiP.melanampyxP.vittatus R. daniconiusT. khudree
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 219
Fig.6.18 Relative biomass of fish recorded during monsoon season from Idukki reservoir
Fig.6.19 Relative biomass of fish recorded during postmonsoon season from Idukki reservoir
0.06 %0.06 %2.76 %
39.35 %
2.54 %
0.17 %18.63 %
9.22 %
2.32 %
0.07 %0.04 %
2.90 %1.17 %0.03 %0.03 %
0.04 %0.04 % 20.58 %
A. lineatusB. bakeriC.catlaC. gachuaC. cirrhosaC. batrachusC. carpio L. rohitaM. guentheriM. vittatusN. rupecolaO.bimaculatusO.mossambicusP. dayiP.melanampyxP.vittatus R. daniconiusT. khudree
0.24 %0.14 %
29.75 %
8.93 %
16.24 %0.02 %2.26 %
5.85 %0.31 %0.11 %
9.03 %
2.49 %
0.10 %
0.13 %
0.14 %
0.16 % 24.12 %
A. lineatusB. bakeriC. gachuaC. cirrhosaC. carpio H. fossilisL. rohitaM. guentheriM. vittatusN. rupecolaO.bimaculatusO.mossambicusP. dayiP.melanampyxP.vittatus R. daniconiusT. khudree
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220 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
6.3.5 Species richness and diversity indices of fish population
The comparison of fish species richness in 3 seasons at each sampling
station is given in Fig.6.20. Among the 16 stations studied, species richness
ranged from 10.33 to 14.33 which showed more or less similar values in 3
seasons with slight higher values during postmonsoon. During postmonsoon
season, highest species richness (14.33) was recorded at station 16 and lowest
(12) was observed at stations 1, 9 and 11. Monsoon season showed highest
species richness (13.67) at stations 12 and 16 while the lowest (10.33) at
station 6. In premonsoon, highest species richness (13.33) was observed at
station 10 while lowest richness (11.67) was recorded at station 8.
Fig.6.20 Seasonal variations in species richness (mean) of fish recorded at various
stations in I dukki reservoir
Margalef’s richness index values recorded at different stations and
seasons are given in Fig. 6.21 where the high values were obtained during
monsoon and postmonsoon season than that recorded during premonsoon
season. Among stations, the Margalef’s richness values ranged 2.643 at station
6 to 3.170 at station 16 during premonsoon season. In monsoon season, it was
0
4
8
12
16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Spec
ies r
ichne
ss
Stations
Premonsoon Monsoon Postmonsoon
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 221
ranged from 2.847 at station 6 to 3.675 at station 16. Margalef’s richness value
varied from 3.067 (station 11) to 3.732 (station 16) in postmonsoon season.
Fig.6.21 Seasonal variations in Margalef's richness (mean) of fish recorded at various stations in I dukki reservoir
Fig. 6.22 shows the Shannon-Weiner diversity values recorded at the
16 stations studied during different seasons where both postmonsoon and
monsoon seasons showed higher values than that of premonsoon. During
postmonsoon season, the Shannon-Wiener diversity indices of the fish fauna
was high (2.472) at station (16) and low (2.204) at station (11). In monsoon
season, it varied between 2.175 at station 6 to 2.483 at station 16. Premonsoon
showed the indices value between 1.939 (station 4) to 2.302 (station 7).
The Pielou’s evenness values were observed high during monsoon season
in the reservoir. Evenness values were low during premonsoon season while
moderate values recorded during postmonsoon season (Fig. 6 .23). In monsoon
season, the evenness values were recorded high at station 1 (0.967) and low at
station 14 (0.910). In postmonsoon season, it was high at station 9 (0.939) and
2.00
2.202.402.60
2.803.00
3.203.40
3.603.80
4.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Mar
gale
f's r
ichne
ss
Stations
Pre monsoon Monsoon Post monsoon
Chapter 6
222 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
low at station 11 (0.887) whereas in premonsoon season the evenness values were
observed high at station 16 (0.924) and low at station 4 (0.799).
Fig.6.22 Seasonal variations in Shannon diversity (mean) of fish recorded at various
stations in I dukki reservoir
Fig. 6.23 Seasonal variations in Pielou's evenness (mean) of fish recorded at various
stations in I dukki reservoir
1.50
1.70
1.90
2.10
2.30
2.50
2.70
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Shan
non
div
ersit
y
Stations
Pre monsoon Monsoon Post Monsoon
0.70
0.90
1.10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Piel
ou's
even
ess
Stations
Pre monsoon Monsoon Post monsoon
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 223
6.4 Discussion
The study conducted in the Idukki reservoir revealed that this reservoir
was having a moderate fish composition and diversity when compared to other
large reservoirs in the country. Fishes belong to 19 species, 18 genera and 11
families were recorded in the study period from Idukki reservoir. The
distribution of fish species is variable due to geographical and geological
conditions of reservoir (Shaik et al., 2011). The physico-chemical factors also
influenced the distribution, abundance and type of organisms of the reservoirs
and these factors vary from region to region. Each reservoir has an individual
capacity and production which also varies from one to another (Gundu, 2011).
Pisca et al. (2000) reported 28 species of fish belonging to four orders from
Ibrahimbagh reservoir of Andra Pradesh. Sakhare (2001) recorded 23 species
belonging to 7 orders in Jawalgaon reservoir, Maharashtra. Pawar et al. (2003)
studied the fish diversity of Shirur dam (Maharashtra) and confirm the
occurrence of 11 fish species belong to 5 orders. Mohapatra (2003) recorded a
total of 43 fish species in Hirakud reservoir of Orissa. 46 fish species were
reported from the Rana Pratapsagar reservoir in Rajasthan by Juyal and
Chaudhary (2003). Sakhare (2005) recorded 28 species of fish belonging to 19
genera in the study conducted in Manjira reservoir in Maharastra. Shinde et al.
(2009) recorded 15 fish species represented by three orders in the Harsool-
Savangi dam in Maharashtra. Negi (2008) recorded 51 species of fish in
Gobindsagar reservoir and 28 species in Pong reservoir (Himachal Pradesh).
Rao et al. (2011) recorded 24 species of fish under 12 families and 6 orders
from Pocharam lake (Andra Pradesh) and 22 species of fish under 17 genera,
11 families and 6 orders from Wyra lake (Andra Pradesh). These studies agree
that with 19 species under 18 genera, Idukki reservoir contains moderate fish
production.
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224 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
During the present study, family Cyprinidae recorded 39% of the fish
recorded from this reservoir which also agree with the earlier findings of
Gopinath and Jayachandran (1984) in Idukki reservoir. Battul et al. (2007)
reported 18 fish species from Ekrukh reservoir of Maharashtra where
Cyprinidae family is dominant with 8 species. Khedkar and Gynanath (2005)
recorded 37 species from Issapur dam of Maharashtra where Cyprinidae
family is dominant with 20 species. The ichthyofauna of Ambadi dam
(Maharashtra) was reported by Ubarhande et al. (2011) which belong to 8
orders, 11 families, 22 genera and 27 species where Cyprinidae family is
dominant with 13 species which makes 48.16 % of total fish. The study
conducted in certain reservoirs of Karnataka state also recorded more
abundance from family Cyprinidae (Venkateshwarulu et al., 2002; Wakid and
Biswas, 2005; Thirumala et al., 2011).
In Idukki reservoir, the premonsoon season recorded the highest fish
abundance followed by postmonsoon and the lowest in monsoon. According
to Mondal and Kaviraj (2009) and Mondal et al. (2010), number of fish
species and the species density fluctuated between the seasons. The significant
abundance of fish species in the dry season may be due to the reduced water
level, high rate of transparency and increased availability of food as reported
by Mustapha (2009a). The abundance of fish species in the dry season was
documented by various workers like Elliot (1986), Horne and Goldman (1994)
and Araoye (1997). Horne and Goldman (1994) reported a positive correlation
between fish abundance and warm temperature. Mustapha (2009a) opined that
the warm temperature and high transparency in the dry season promoted high
fish catches in Nigerian reservoirs. The high fish abundance recorded during
premonsoon and postmonsoon months in the three years of study in Idukki
reservoir also agrees with these findings. Flood, low transparency, high water
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 225
volume and inefficiency in gill net operation might have caused the decline in
population during monsoon months as reported by Mustapha (2009a). Species
number increased during postmonsoon rendering an increase in the Shannon-
Weiner index (Mondal et al., 2010).
The diversity index analysis also indicates that the postmonsoon and
monsoon seasons are more productive than premonsoon season which
coincides with the favourable postmonsoon and monsoon conditions such as
sufficient water and ample food resources as reported by Thirumala et al.
(2011) as noticed in Bhadra reservoir of Karnataka. The low species diversity
during premonsoon was probably due to the shrinkage of water spread of the
reservoir (Thirumala et al., 2011) and fishing pressure (Kar et al., 2006). High
production of fish during monsoon season and subsequent reduction during
other seasons due to competition and fishing pressure were also reported by
Kar et al. (2006) in the Lake Sone (Assam). The results of the present study
fully corroborate with this. The high evenness recorded during monsoon
season may be due to the high water spread and distribution during this season
as reported by Thirumula et al. (2011).
Fishes belong to 19 species, 18 genera and 11 families were recorded during
this study showed a slight difference in fish faunal composition when compared to
the study conducted by Gopinath and Jayachandran (1984). They recorded a total of
17 species belonging to 14 genera, 8 family in 6 orders. The increase in fish species
recorded in the present study may be lack of much fishing pressure in the reservoir
and this gives an indication that this reservoir can provide a favourable niche for the
fish production. The commercial fishery in this reservoir is not allowed except for
tribal communities living in and around the catchment area and this may be one of
the reason for the increase in the fish species in this reservoir. The species such as
Barilius bendelisis, Puntius bovianicus, Garra lamta (Family - Cyprinidae),
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226 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
Nemacheilus denisonii and Nemacheilus scaturigina (Family - Cobitidae) recorded
by Gopinath and Jayachandran in 1984 were not observed in the reservoir in the
present study. The presence of Barilius bakeri, Catla catla, Puntius vittaus, Labeo
rohita (Family - Cyprinidae), Mystus vittatus (Family - Bagridae), Clarius
batrachus (Family - Clariidae) and Parambassis dayi (Family - Ambassidae) in
the reservoir were newly recorded during the present study.
In Idukki reservoir, the exotic species like Oreochromis mosambicus,
Cyprinus carpio and other Indian major carps were introduced by various
authorities like Department of fisheries, Forest department and Panchayat
bodies etc. without any specific plan and reason. There was no record on the
recent introduction of the fish in this reservoir but in the present study the
presence of Oreochromis mosambicus and Cyprinus carpio were noticed in
reasonable quantities which indicate that the reservoir support the growth of
exotic species also along with the indigenous species.
According to Padmakumar et al. (2008), the main challenges in
enhancing fish production are mainly the degradation of aquatic environment,
increased competition for resources and inadequate institutional system. The
low fish productivity of most of the reservoirs in kerala is attributed to
undesirable species mix, lack of scientific database, inadequate stocking,
wrong selection of species and multiple ownership. The state electricity board
has control over the reservoirs under hydro - electric project and those in the
reserve forest are under the forest department. Fisheries department has access
only to the irrigation reservoirs. This multiple ownership comes in the way of
scientific management of reservoirs. The fish production in Idukki reservoir
clearly indicates that by proper and efficient management, this reservoir can be
turned as an extremely productive one and it can produce enviable spectrum of
fish genetic resources which can lead to a many fold increase in inland fish
Ic hthyofauna of Idukki Reservoir
Studies on Physico- chemi cal charact eristics, Plankton diversity and I chthyofauna of Idukki reservoir, Kerala, India 227
production in the state. The quality of water free from any sort of pollution in
Idukki reservoir also provides a favourable niche for fish production.
A large number of reservoirs or man-made lakes have been developed
to provide water for irrigation and power for industries. Growing of fish in
these reservoirs involves non-consumptive use of water. In a developing
country like India, these reservoirs can play a vital role in augmenting fish
production for human consumption. In China large quantity of fish is produced
from reservoirs and considers it as culture fisheries (Srinivasan, 1999).
Effective scientific management plan has to be framed to begin fish production
from all reservoirs in India to increase the inland fish production from the
country. The right kind of management system does help in keeping the stocks
at sustainable levels within the enviormental functions of the system (Gundu,
2011). In order to compensate for riverine fish production decline, the
intensive management vis-a-vis enhancement will have to be undertaken in
reservoir ecosystems. Reservoirs have immense scope for enhancing fish
production through adoption of culture based technology (Bhukaswan, 1980
and Jhingran, 1986).
Reservoirs like Idukki which are built only for power generation and
irrigation can be turned to important fish production centres which would
enhance the productivity and livelihoods for the inland fishers. Fishing rights
in Idukki reservoir is given only to the tribal community living in an around
the reservoir. Fishery enhancement programmes in this reservoir would
definitely help to develop the livelihood of this people.
Reservoirs constitute the prime inland fishery resources of India by
virtue of their vast area and huge production potential. Besides being
contributed to the yield enhancement, fisheries development of reservoirs
directly benefits to the weakest sections of the society who depend on the fish
Chapter 6
228 Studies on Physico-chemical characteristics, Plankton diversity and Icht hyof auna of Idukki res ervoir, Kerala, India
resources of the reservoir for their livelihood. The benefits accrued due to
increase in yield and income generation directly contributes to improvement in
the quality of life of fishermen (Vass, 2007). Thus by enhancing the fish
production in Idukki reservoir, it can benefit to the tribal community
development. Considering the immense potential of Idukki reservoir, there is a
need for close co-ordination among the various stake holders and adoption of a
holistic development approach to develop reservoir fisheries as suggested by
Vass (2007).
*******