Seasonal Occurrence of Fin Fish and Shell Fish Species Collected from Arasalar Estuary, Thanjavur District, Tamil Nadu, India

Estuaries are one of the highly productive ecosystems that are important both ecologically and economically. Besides being a rich source of protein, Estuaries also provide a major source of live hood for people living in these areas. Hence a present study attempted to identify the different type of fish that occur in Arasalar Estuary, situated in Thanjavur District of Tamil Nadu, India. A total of 25 species belonging to 20 families of Fin Fish could be recorded in the different seasons. Rainy season recoded 25 species belonging to 20 families while pre summer season recorded 19 species belonging to 17 families and summer season recorded 21 species belonging to 19 families post summer season recorded 24 species belonging to 18 families 7 species of shell fishes were recorded with rainy and pre summer seasons recording 4 species each, summer season recording 7 species and post summer season recording 6 species. An overall percentage composition of the various fin fish species during pre-summer season reveals that it ranged from 0.02 to 35.90%. The order of hierarchy in terms of percentage composition was Henuramphida > Anguillidae > Arridae > Bagridae > Elopidae > Scatophagidae > Megalopidae > Carangidae > Terapantidae > Cyprinidae > Mugilidae > Solerdae > Ambassidae > Cichclidae. With regard to the shell fishes, the lowest percentage composition was represented by M. dobsoni of Penaeidae (0.04%) and the highest by M. rosenbergi belonging to the family Palaemonidae (0.71%). Here also, while the minority composition kept changing with season, the majority was always represented by P. indicus except for rainy season when the majority was shown by M. rosenbergi.