FIRST RECORD OF ESCUALOSA THORACATA VALENCIENNES IN FRESH WATER ZONE OF HOOGLY ESTUARY NEAR DAKSHINESHWAR

Abstract

Escualosa thoracata Valenciennes belonging to order-Clupeiformes, family-Clupeidae and sub-family-Clupeinae is a widely distributed species inhabiting along the western and eastern coasts of India and seas of Burma to the Malay Archipelago (Day, 1889; Mishra, 1962; Fischer and Bianchi, 1984). But it is most abundant in the Kerala and Coromandal coasts. The members of subfamily Clupeinae are mostly marine in habitat, but the juveniles of Sardinella sp. and E. thoracata enter in the lower parts of Ganga river (Talwar and Jhingran, 1991). It feeds on zooplankton viz. copepods, crab, zoea, larvae of bivalves and fish eggs and phytoplankton (Coppola et al.,
1994). The species breeds during October to February with a peak from November to January off western coast of India, usually in relatively shallow inshore waters (Whitehead, 1985). It attains standard length (SL) of 10.0
cm with a life span of about one year (Jeyaseelan, 1998; Eschmeyer, 1998). The species is pelagic in nature and its catch is reported from fresh, brackish and marine water in a depth range of 0 to 50 m. However at present there have been no report of its availability in the freshwater stretch of river
Ganga. It is amphidromous i.e. it regularly migrates between freshwater and the sea in both directions, but not for the purpose of breeding, as in anadromous and catadromous species. Migration is thought to be cyclical and predictable and cover more than 100 km. Juveniles apparently entering the lower parts of rivers in a school, but return later to the sea 
(Riede, 2004).