On some aspects of the Biology of Coilia dussumieri(Cuv. and Val.)

Abstract

The smaller sized individuals of C. dussumieri apparently inhabit shallower and inshore waters, while the larger fish live in deeper and OS-shore waters. The inshore waters are fished intensively during the monsoons, resulting in a preponderance of fish below a length of 110 mm in the catch. Due to the protracted spawning period of the fish, there is no progression of modes in the monthly length frequency distributions. The size at first maturity has been estimated at 131-140 mm. The sex ratio of 53 41 males: 46 59 females deviates significantly from the 50:50 ratio. Males outnumber females in higher length groups, probably because the females migrate to offshore grounds at a smaller size.. The spawning season probably extends from September to March. The fish has a protracted spawning period and spawns more than once in each spawning season, The total number of possible spawnings has been estimated at three, from the ratio of the number of ova in the last batch to the number of remaining maturing eggs,. The ponderal index curve changes slope at 130 mm., considered to be the size at first maturity, There are no regular seasonal variations in the ponderal index. Fecundity is estimated at 1200 to 4200 eggs per spawning.