Some aspects of spawning biology of indian oil sardine Sardinella longiceps valenciennes

Abstract

Although Homell (1910) made a few observations on the spawning habits and migratory movements of Indian oil sardine. Sardinella longiceps, the first concerted attempt to "understand its maturity and spawning habits and to delimit the spawning season can be said to have been made by Homell and Nayudu (1924). Following this, Devanesan (1943), while confirming some of the earlier findings, also contradicted certain others. Later, Nair (1953 & 1959). giving a detailed review of earlier investigations, did not agree with some of the observations of previous workers in addition to providing more information to our knowledge on the spawning habits of oil-sardine based on his study from 1948 to 1955. Since these authors had to divide their attention not only to administrative problems but also to various other aspects of biology of the fish at the same time, it is but natural that conclusions have been drawn with limited data at their disposal. Since it is well known that a fishery which is dependent on a few age classes is much more affected by the success or failure of spawning in any one year than which operates on many age groups and in view of the fact that determination of the spawning season and frequency of reproduction within the season and within the life span of the fish are essential prerequisites in assessing the reproductive potential of a population, it is necessary that contradictory views expressed by earlier workers are thoroughly analysed and a more precise information is obtained to formulate future programme of work. With the expanding activities of Central Marine Fisheries Research Institute, the author was given an opportunity to concentrate solely on this problem of maturity and spawning habits and the results of his investigation based on five spawning seasons from 1959 to 1963 at Calicut are herein reported.