The Cauvery river is one of the major rivers of India, and perhaps, physically the most remarkable river of the Peninsula. The river originates at Talakaveri, Kodagu district of Karnataka in the Western Ghats and flows generally south east through Karnataka and Tamil Nadu and across the southern Deccan plateau through the southeastern lowlands, and finally emptying into the Bay of Bengal. It is considered India's fourth largest river, draining about 89,600 sq. km.
The Cauvery estuary, located along the east coast of India, is a part of the Cauvery river basin. The Cauvery delta begins from the Grand Anicut near Tiruchirapalli. The studies on the fauna of Cauvery estuary are very scanty, and no detailed information on the fish, crustacean and molluscan fauna is available. Therefore, to fill this gap, the authors have taken up the present study on the crustacean, molluscan and ichthyofaunal resources of the Cauvery estuary to provide valuable information on diversity, ecology and distribution patterns, which can be utilized for their sustainable utilization, management and conservation of the resources.
The present studies revealed the occurrence of 82 species of fish belonging to 66 genera and 41 families; 21 species of prawns belonging to 12 genera and 3 families; 22 species of crabs belonging to 13 genera and 9 families and 31 species of molluscs belonging to 22 genera and 16 families. A systematic checklist of the fauna of Cauvery Estuarine System has been provided. The similarity of the species composition of fishes, prawns and crabs between Cauvery estuary and other estuarine and brackish water bodies of the east coast of India are discussed.