THE FISHES OF THE KOLLERU LAKE, ANDHRA PRADESH, INDIA WITH COMMENTS ON THEIR CONSERVATION

Kolleru Lake is one of the National wetlands and the largest freshwater lakes of our country. Wetlands are very important productive ecosystems and their socioeconomic values are well established. Moreover, the riverine fishes use wetlands as their breeding grounds. In addition to these, this lake has been found to contain some threatened species of fishes, which needs to be conserved to protect them from extinct in near future. Considering these f~rts an attempt has been made to estimate the Fish resources of this lake. This work is based primarily on the fish collections from this lake by the author (Barman, 1993) in addition to the fishes recorded from this lake following the works of Chacko et al. (1952) and Dutt & Murthy (1971 & 1976). This Lake has been found to contain 51 freshwater fish species belonging to 35 genera, 21 families and 9 orders. A review on the fishes of this lake shows that it contains 4 endangered, 11 vulnerable and 1 rare species following the works of Molur and Walker (1998) and Menon (1999) as per the guidelines and criteria provided by the IDCN for determining the threatened species. Almost all the fishes of this lake are commercially important. Since this lake contains some important commercial fishes and 16 threatened species, it has been suggested for conservation specially to protect the threatened species and to maintain its biodiversity of the fishes as a whole.


INTRODUCTION
Kolleru Lake is one of the National wetlands and the largest freshwater lakes of our country.
Wetlands are very important productive ecosystems and their socioeconomic values are well established.Moreover, the riverine fishes use wetlands as their breeding grounds.In addition to these, this lake has been found to contain some threatened species of fishes, which needs to be conserved to protect them from extinct in near future.Considering these f~rts an attempt has been made to estimate the Fish resources of this lake.This work is based primarily on the fish collections from this lake by the author (Barman, 1993) in addition to the fishes recorded from this lake following the works of Chacko et al. (1952) and Dutt & Murthy (1971& 1976).This Lake has been found to contain 51 freshwater fish species belonging to 35 genera, 21 families and 9 orders.
A review on the fishes of this lake shows that it contains 4 endangered, 11 vulnerable and 1 rare species following the works of Molur and Walker (1998) and Menon (1999) as per the guidelines and criteria provided by the IDCN for determining the threatened species.Almost all the fishes of this lake are commercially important.Since this lake contains some important commercial fishes and 16 threatened species, it has been suggested for conservation specially to protect the threatened species and to maintain its biodiversity of the fishes as a whole.

TOPOGRAPHY
The Lake Kolleru is a natural depression with an average depth of 1 metre and a maximum depth of 3 metres during the southwest monsoon, in the coastal belt between the deltas of the river Godavari to the east and Krishna to the west.It is located partly in Krishna and West Godavari districts of Andhra Pradesh.The Eluru canal (irrigation canal) connects these two rivers to the north of this lake and the Bay of Bengal passes to its southwest side.This lake has an area of almost 250 sq.km.Four major streams, viz., Budameru, Thammileru, Ramileni and Gunderu and several irrigation channels open into this lake, carrying a considerable amount of silt in this lake.The Bay of Bengal is 32 km.away and is connected to this lake by one outlet, named Upputeru.This lake is a low-lying swamp type with almost 85% freshwater dominance.Although the lake is connected with the Bay of Bengal through Upputeru, the tidal waters do not enter into the lake proper, so the freshwater fishes can thrive there well.

SYSTEMATIC ACCOUNT OF THE FISHES OF THE KOLLERU LAKE
The classification of Greenwood et al., (1966) and Menon (1999) is followed here in listing the fishes of this lake as follows : Order I ANGUILLIFORMES The Lake Kolleru is one of the very important freshwater lakes and National wetlands of India.Many riverine important edible fishes utilize this wetland for their breeding grounds.The presence of juvenile specimens of almost all the fishes especially the carps in this lake indicates that these fishes use this water body as their spawning grounds.Since this lake is distantly connected with the Bay of Bengal through Upputeru often some marine fishes are also found in the fish fauna of this lake.Among the important commercial fishes of this lake Anabas testudineus, Heteropneustes fossilis and Labeo rohita are abundantly found throughout the year.This lake also has been found to contain 3 endemic species of our country.Rohtee ogilbii of this lake is a vulnerable and endemic fish species of our country.This species is found only in the two important south Indian waters of the dver Godavari and Krishna.Hypselobarbus dobsoni is an endangered and endemic species in India.It has been recorded in the south Indian waters of the Rivers Krishna and Cauvery, and in the Anaimalai Hill drainages.Thynnichthys sandkhol is a rare and endemic fish species of India, found in the south Indian waters of the river Gadavari and Krishna only.Since these commercially important vulnerable, endangered and rare fish species are already in danger of extinction due to over exploitation, habitat destruction and other external factors, their protection and conservation measures should be taken immediately to save them from extinction.
To protect and conserve the fish resources along with its vulnerable, endangered and rare fish species of the Lake Kolleru the following measures may be undertaken : (1) Indiscriminate fishing by means of fixed engines should be stopped.
(2) Restrictions on the use of certain nets during the specified times of the year from April to June (i.e., closed season) as well as mesh size (usually the minimum mesh size of the nets pennitted is 25 mm. in the Indian waters).
(3) Restrictions on the capture and sale of legal sizes of fry and fingerlings of major carps to protect the juveniles of the fishes.
(4) All types of landscapes alterations must be controlled and use of herbicides and insecticides also to be prohibited in and around this lake.