Reproductive Biology of Estuarine Whiting, Sillago Vincenti (Mckay, 1980)

By : N. Manjappa , N. Basavaraja , H. N. Anjaneyappa

Page No: 95-110

Abstract
This study was conducted with a view to document some of the reproductive traits of the estuarine whiting, Sillago vincenti (family: Sillaginidae). The length-weight relationship of S. vincenti indicated that the weight of the fish increased almost the cube of the length. The observed sex ratio indicated the dominance of males over females and the ratio was found to be 1:0.30; the males were dominant in the population in all the months. The gonado-somatic index (GSI) of male was found to be lowest (0.24%) in April, while the highest (1.43%) value was observed in November. In female, the lowest (0.65%) GSI value was recorded in May, while the highest (3.44%) value was observed in the month of September. The absolute fecundity was found to vary from 12,686 to 1,16,248 eggs with an average of 44,277 eggs, depending upon the size of fish.The GSI and maturity stages indicate a prolonged breeding season, with one or two peaks in a year. The histological examination of ovary of S. vincenti revealed the presence of oocytes at different stages of maturity. The immature ovary showed maximum percentage of oogonia, while the mature gonad had maximum proportion of mature, ready-to-ooze oocytes and vitellogenic atretic oocytes. The spent stage showed oocytes at different stages of development and corpus luteum. In male, the testis showed the presence of spermatogonia, spermatocytes, spermatid and spermatozoa at various stages of development. However, the spent fish showed the presence of empty testicular lobules and some residual spermatozoa.

Authors :
N. Manjappa
Fisheries Research and Information Centre (Inland), Hesaraghatta, Bengaluru-560 089, Karnataka

N. Basavaraja
Department of Aquaculture, Karnataka Veterinary, Animal and Fisheries Sciences University,College of Fisheries, Mangalore-575002, Karnataka, India

H. N. Anjaneyappa
Department of Fisheries Resource and Management, Karnataka Veterinary, Animal and Fisheries Sciences University, College of Fisheries, Mangaluru-575002, Karnataka.