A study on the piscifauna of the Idukki Reservoir and catchment area

Item Type article

Authors Gopinath, P.; Jayakrishnan, T.N.

Download date 24/09/2021 20:41:44

Link to Item http://hdl.handle.net/1834/33841 dy on e sdfauna of the I u ldd eservoh· an atch ment Area

P. GOPINATH and T. N. JAYAKRISHNAN Zoological Survey of , Cochin- 682 011

From the area under report 17 species, 15 endemic and 2 exotic, of freshwater fish have been identified. Of these, 8 species are commonly found in the catches and are of fishery significance. The fact that small fish species which have no fishery importance also support life in other trophic levels of this ecosystem is well exemplified by the intera­ ction of the birds and mammals with these species. A scientific management and moni­ toring of the reservoir waters as well as the remaining segments of forests are recommend­ ed to salvage the wild life and vegetation from a possible rapid deterioration within years.

Fish population is highly susceptible to spread over an area of 59.80km 2 and com­ the changes in the ecosystem and when these bines the course of the and changes exceed beyond the tolerence level rivers. The catchment area of of the fish the population depletes. This the reservoir is 649.30km2 with gross storage in turn affects the floral and faunal elements capacity of 1996.3 Mm3 • The maximum at various trophic levels of the ecosystem. water level recorded was 734.3 m, when the In this context the present study is designed hillocks within the reservoir area would be to know the status of fish population in and submerged. The average depth of the reser­ around the ·reservoir waters. The signi­ voir varies from 50 to 80 m. During the ficance of this study is relevant, especially monsoon season the depth increases upto when one envisages that the changes caused 125 m or above around the . Since by a hyde! project on the piscifauna need the water of the Periyar River enters the not necessarily be deleterious. The present reservoir through Ayyappancoil, this zone study, first of its kind in the hyde! project area of Idukki, is an attempt to know could be considered as the upstream of the the diversity and abundance of the reservoir and is termed as the Periyar reach. various fish species in the reservoir waters The fish of the Periyar have access to the and catchment area. Besides, attempts reservoir only through this inlet. After the were made to analyse the interaction of fish construction of the the Cheruthoni River population with other faunal elements, aqua­ vanished into the reservoir waters. The tic as well as terrestrial in the ecosystem. traces of the old Cheruthoni River could be seen on the side of the spillway where Study area the water is released from the . The fish fauna of the reservoir should The studies were carried out in the Idukki therefore include the fish from both these Reservoir and the places surrounding it, rivers. At K.ulamavu the impounded water in Western Ghats at an altitude of about is diverted through a power tunnel, 2027 m 850 m above M.S.L., (Long. 76°59' E and long and 7 m in diameter into an under­ Lat. 9°51' N). The Idukki Hydel Project is a complex of three dams, namely, the Idukki ground power house at , which Double Arch Dam across the river Periyar, generates about 355 mw of power. After the Cheruthoni Concrete Gravity Dam the power is harnessed the tailrace water adjacent to the and the biggest joints the river. This part masonry K.ulamavu Dam located about of the reservoir could be considered as the 30 km upstream of Idukki, on the left bank downstream of the reservoir and is termed of the reservoir (Fig. 1). The reservoir is as the K.ulamavu reach.

FISHERY TECHNOLOGY PISCIFAUNA OF IDUKKI RESERVOIR 132

D Res~rvoir ® Landing centres Collecting centres

Fig. 1. Idukki reservoir showing the sampling and collection centres

Materials and Methods every month from September, 1982 to July, 1983 to collect fish samples to estimate the Quite a few inhabitants of the area around weight of each fish species in the landings. the reservoir are engaged in fishing in and The identification of the fish to the species around the reservoir waters, and the materials level has been confirmed by the ichthyologists for the present study are collected from these of the Zoological Survey of India, Calcutta. people, from Venganam, Pothumattom and The general classification of the fish adopted Manjakkuzy in· Kulamavu reach and Kochi­ in the present study is that of Jayaram (1981) dukki, Seethakkayam and Ayyappancoil in and Rosen & Patterson (1969) with slight Periyar reach (Fig. 1). The fishing gear modifications. With the aid of a 7 x 50 they use is known locally as 'Thandadivala' binoculars, attempts were made regularly to or 'Kettuvala', which has mesh sizes varying observe bird species used to prey on the fish from 26 mm to 180 mm with strings of population of the reservoir. thickness ranging from ~ mm to 2 mm, a crude gillnet, with no floats and weights. The catches obtained by this gear are sele­ Results and Discussion ctive, since the fishermen are concerned only about those fish which can readily be sold. The list of fish species (Table 1) includes Efforts have been made therefore to collect 17 species belonging to 6 orders, 8 families fishes from the reservoir, as well as from the and 14 genera. Among these, Cyprinus streams and puddles of Meenmutty, Kuda­ carpio, and Tilapia mossambicus are exotic murutty and Karimpan, using boxnet, species introduced into the reservoir by castnet and cloth pieces Inland Fisheries Department about 1975, and the rest are endemic. The catches are regularly being brought to the landing centres at Mayyanna, Nelli­ The quantitative analyses of the fish landed kappara etc. in Kulamavu reach and Vellapp­ from September, 1982 to July, 1983 at the ara, Vazhavara etc. in Periyar reach (Fig. I) landing centres are given in Fig. 2. During These landing centres were regularly< visited this period a total of 705.97 kg. of fish was

Vol. 21, 1984 133 P. GOPINATH AND T. N. JAYAKRISHNAN

Table 1. List of freshwater fish species

study area J::.~ -" -~--"- (/) Order CYPRINIFORMES 26 :J 0 Family CYPRINIDAE :0 E 0 Sub family Rasborinae (/) 220 (/) Genus Rasbora 0 1. R. daniconius 200 ~ ....,E Genus Barilius 0>190· 2. B. bendelisis .>< Sub family Cyprininae ,!; 16 .:::1 Genus Cyprinus .2' Q) 3. C. carpio* 31: 120 Genus Puntius 4. P. melanampyx 100 5. P. bovianicus 00 Genus Tor 6. T. khudree Genus Cirrhinus 7. C. cirrhosa Sub family Garrinae Genus Garra Species 8. G. lamta Fig. 2. Quantity of various speeies of fish. Family COBITIDAE landed during September '82 to Sub family N oemacheilinae July '83 Genus Noemacheilus 9. N. denisonii Table 2. List of birds regularly feed on the 10. N. scaturigina fish of the reservoir 11. N. rupicola Order SIL URIFORMES Common name Zoological name Family SILURIDAE Genus Ompok Dabchick Podiceps rujicollis 12. 0. bimaculatus Darter Anhinga rufa Family HETEROPNEUSTIDAE Little cormorant Phalacrocorax niger Genus Heteropneustes Cattle egret Bubulcus ibis 13. H. fossilis Little egret Egretta garzetta Order A THERINIFORMES Common sand piper Tringa hipoleucos Family CYPRINODONTIDAE Night heron Nycticorax nycticorax Genus Aplocheilus Pond heron Ardeola grayii 14. A. lineatus White-breasted Halcyon smyrtensis Order CHANNIFORMES kingfisher Family CHANNIDAE Small blue kingfisher Alcedo atthis Genus Channa Pied kingfisher Ceryle rudis 15. C. gachua Order PERCIFORMES Family CICHLIDAE analysed. In the landings, though 8 -spe­ Genus Tilapia cies are common, only 6 species are abun­ 16. T. mossambicus* dant; the two species, Ompok bimaculatus Order MASTACEMBELIFORMES and Heteropneustes fossilis, because they Family MASTACEMBELIDAE contribute only 2.01 kg and 0.26 kg, respe­ Genus M astacembelus ctively, are not included in the histogram. 17. M. guentheri Tor khudree is the most abundant, contri­ buting 267.67 kg. Channa gachua, which * exotic species weigh 7. 78 kg, is the least abundant in the landings. Cirrhinus cirrhosa weighed 32.53

FISHERY TECHNOLOGY PISCIFAUNA OF IDUKKI RESERVOIR 134 kg and Mastacembelus guentheri 10.22 kg. 649.30 km2 need not necessarily represent Cyprinous carpio and Tilapia mossambicus, all freshwater fish reported from with 197.69 kg and 187.79 kg are second (Pillay 1929; John 1936; Hora & Law 1941; and third in abundance. Raj 1941) which comprises a larger area. It is quite possible that certain species which Eleven bird species which mainly depend are well adapted to the habitat of flowing upon the fish population of the reservoir for waters might have failed to cope up with their food are listed in Table 2. Of these, 8 the new habitat and environment of the closed, species are water-birds and the rest are the static water of the reservoir. Owing to the main fish-eaters among the avifauna. changed condition of the lacustrine environ­ ment some of the fish may evolve into newer In the absence of previous studies from types (Tilak & Sharma 1982). The original this area before the dam was constructed it fauna of the reservoir may perish and later is not prudent to say that the piscifauna of a new generation of adaptive forms may the reservoir is depleted. But the present populate the waters at a later stage (Hora study gives a clear picture of the status of 1947). the piscifauna of the area at present. The 15 endemic species reported in this work The fish yield from the reservoir constitute only 19.7 3% of the 7 6 species of The presence or absence of animal life in freshwater fish reported by Hora & Law an ecosystem clearly reflects the quality and (1941) from the Travancore area. The richness of that ecosystem. The 8 commonly study of Hora & Law (1941) includes the seen species, 6 endemic and 2 exotic, of the fish from the Periyar River and it is quite fish landings in and around the reservoir natural to expect, if not complete, a partial waters constitute the fish of fishery signifi­ representation of the fish species of the Peri­ cance of the reservoir waters (Fig. 2). These yar river in the reservoir. Raj (1941) des­ species constitute 53.33% of the 17 species cribes a new genus of Schizothoracinae from cited from this area. The abundance of the Periyar is not represented in the present 3 endemics pecies, T. khudree, C. cirrhosa and study. If the information furnished by the C. gachua in the catches indicate that these local inhabitant could be believed the spe­ are the most successfully established fish cies described by Raj (1941) which is known species of this habitat. From a subjective as 'Brahmanakandai' is seen in the reser­ analysis of the observations made, it could voir though very rarely. Similarly Hora & be stated with certainty that smaller fish like Law (1941) reported certain Homalopterinar: Noemacheilus sp., Puntius sp. etc. which sp. from Travancore whereas the present hardly have any fishery importance are as report does not refer to this family. Jayaram abundant as any other big variety of fish. (1981) reports 742 species of freshwater fish From the fishery point of view these species from India including the exotic species are insignificant but ecologically are indis­ introduced into the Indian freshwaters. Of pensable to maintain life in other trophic these, only 10.20% is reported in Travancore levels of the lacustrine ecosystem. The and 2.29% in the study area under report. abundance of the exotic species over the endemic species points to the conclusion The present study does not claim to have that these species have accommodated listed each and every species of the reservoir themselves successfully in the ecosystem of but the study certainly is a fair representation the reservoir. Tilapia are well known for of the commonly seen fish species of the their ability to colonise and effectively exploit reservoir. By chance we might have missed the unstable slow water habitat in the tro­ small fish which live in crevices and under pics and subtropis (Lowe-McConnell, 1975). rocks and stones in our collection. At the Moreover, 'Tilapias' sucess in tropical and same time the study team could collect and subtropical habitat has been attributed to incorporate to the present list 7 species-C. their ability to rapidly alter both life history cirrhosa, 0 .bimaculatus, T.khudree,N.denisonii, characteristics and trophic level in response N. sacturigina, N. rupicola and G. lamta­ to the changes in the environment (Freyer & which are not cited among the fresh water Iles 1969). C. carpio prefer waters with piscifauna of Travancore area. The colle­ soft muddy bottom such as highly tro­ ction which are made from a total area of phic lakes and ponds or slowly flowing rivers.

Vol. 21, 1984 135 P. GOPINATH AND T. N. JAYAKRISHNAN

The interaction of the piscifauna with teres­ quite a few fish species plays a pivotal role stria! fauna in preserving this ecosystem from rapid destruction. The reservoir waters in fact The predator-prey interaction of the reser­ protects the tropical deciduous forest around voir ecosystem is evinced by the association from the disturbances of the influx of human of 11 species of birds (Table 2) which feed population to an extent and thE water body chiefly on the fish of the reservoir. The 8 of the reservoir serves as a source of water species of water birds as well as the 3 king­ for the wild life of these isolated forests. fisher species which are very commonly The reservoir water and· the remaining seen in and around the reservoir waters undisturbed forest segments that border the clearly show the significance of the fish in reservoir should scientifically be managed the reservoir. According to the reports and nursed without allowing the outside from the fishermen of this area, the mammal agencies with vested interests to sneak in otter which is supposed to be an endangered and dabble with the vegetation and wild life species and is seen in the reservoir waters, of this area. From an ecological point of mainly feeds on fish. The complexity of an view the reservoir waters and its piscifauna eco-system derives from the multitude of including the other aquatic organisms act interactions such as predation, parasitism and as a vital factor which salvage or control competition which occur between the many at least the wild life, vegetation and forests species of organisms that make up the bio­ of this area from dwindling. logical part of the system (Cairns 1968). We are greatly indebted to Zoological Survey of India for having given an opportunity to work on From a fishery point of view the reservoir an interesting research project like this. We record waters have its own limitations areawise, our thanks to Drs. K. C. Jayaramakrishnan, Joint productionwise and in terms of species Director, Zoological Survey of India, Calcutta and diversity. A qualitative and quantitative P. T. Cherian, Officer-in-Charge, Idukki Project Office, Cochin for their personal interest in the course analysis of the phyto and zooplankton, the of this study. We feel highly obliged to our fellow primary producers of the aquatic ecosystem researcher Dr. N.L.N.S. Prasad for identifying the only can conclusively evaluate the produ­ bird species from the study area. We also thank ction potentiality of the reservoir. However, each and every one in our project who extended their whole-hearted co-operation to make this study the fish occupy a significant trophic level in successful. this ecosystem which support life in other trophic levels in the aquatic as well as terres­ trial realms. Fish can be considered as References terminal producers in an ecosystem and are organisms directly used by man and other Cairns, J. Jr. (1968) Scientist and Citizen, organisms such as mammals, birds, turtles, 10, 187 frogs and sometimes fish itself (Ricker 1978). Though the possibility of fishery exploitation Freyer, G. & Iles, T. D. (1969) Evolution, is bleak in the reservoir waters, it is to be 23, 359 remembered that around 50 people and their dependants around the catchment area rely Greenwood, P. H., Rosen, D. E., Weitzman, on these fish catches for their living as a S. H. & Myers, G. S. (1966) Bull. result of increase in area for the fishery acti­ vities. Effects of dams on fisheries are not Amer. Mus. Nat. Hist. 131, 339 always deleterious. The construction of a darn across a river results in the creation of Hora, S. L. (1941) Rec. Ind. Mus. 41, 221 reservoir which makes available large area of water for production and exploitation Hora, S. L. (1947) Cent. Bd. in·i. J. 4, 337 of fish suitable for such environments (Jhin­ gran, 1982). Hora, S. L. & Law, N.C. (1941) Rec. Ind. Mus. 41, 233 Considering the matters discussed above, in the given· situation it is to be assumed Jayaram, K. C. (1981) The Freshwater that the reservoir which is the part and par­ Fishes of India. Zoological Survey of cel ot the hyde! project and which harbours India, Calcutta

FISHERY TECHNOLOGY PISCIFAUNA OF IDUKKI RESERVOIR 136

J olm, C. C. (1936) J. Bomb. Nat. Hist. Ricker, W. E. (1978) in A1ethods for Soc. 38, 702 Assessment of Fish Product;on in Fresh­ water. Blackwell Scientific Publica­ Lowe-McConnell, R. H. (1975) Fish tions, Oxford, IBP Handbook No.3, p.12 Communities in Tropical Freshwaters. Rosen, D. E. & Patterson, C. (1961) Bull. Longman, London Amer. JI;Jus. Nat. 141, 357

Pillay, R.S.N. (1929) J. Bomb. Nat. Hist. Tilak, R. & Sharma, U. (1982) Game Soc. 33, 347 Fishes of India and Angling. Inter­ national Book Distributors, Dehradun, Raj, S. (1941) Rec. Ind. Mus. 43, 209 India

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