ICHTHYOFAUNA OF IDUKKI RESERVOIRshodhganga.inflibnet.ac.in/bitstream/10603/25968/18/18...Chapter 6 204 Studies on Physico-chemical characteristics, Plankton diversity and Ichthyofauna

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


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



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

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Chapter 6


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

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450

Biom

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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


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



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

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40089

72

2

133

355

2

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3 8

94 101

73

387

148

65

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69 73

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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


Fig.6.6 Total biomass (mean) of fis h recorded from Idukki reservoir

Fig. 6.7 Relative biomass of fish recorded from Idukki reservoir

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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

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1

0.26

0.39

0.32

0.45

81.6

6

Biom

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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



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


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

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70

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

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A. lineatus B. bakeri C. catla C. gachua C. cirrhosa


M. vittatus N. rupecola O. bimaculatus O. mossambicus P. dayi

P. melanampyx P. vittatus R. daniconius T. khudree

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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


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


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

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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


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



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


Fig.6.14 Biomass (mean) of fish recorded during premons oon seas on at various stations


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

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16





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Stations



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

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Chapter 6


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



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

Chapter 6


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



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


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


Fig. 6.23 Seasonal variations in Pielou's evenness (mean) of fish recorded at various


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



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.

Chapter 6


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



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),

Chapter 6


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



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


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).

*******

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ICHTHYOFAUNA OF IDUKKI RESERVOIRshodhganga.inflibnet.ac.in/bitstream/10603/25968/18/18...Chapter 6 204 Studies on Physico-chemical characteristics, Plankton diversity and Ichthyofauna