Ovary as an indicator of frequency of spawning in fishes

Abstract

In majority of the marine fishes from tropical areas, maturation is a continuous process resulting in the occurrence of mature fishes throughout the year. In several Indian marine fishes, because of multiple spawning, a truly spent fish is scarcely found and also difficult to identify. Instead, partially spent fishes have been reported in a number of cases. As the eggs contained in the ovary are progressively ripened and shed, the ovary itself grows smaller, and to the naked eye, seems to reverse the stages by which it attained fuji maturity. The ovaries of such fi shes, though superficially resemble the normal stages III to V, differ from them in macroscopic appearance as well as microscopic structure to some extent. It occurred to the authors that such partially spent ovaries of fishes yield clues to the frequency or spawning in different species. In the present paper, the occurrence and nature of such ovaries and their relation to the frequency of spawning in two species of ribbon-fishes and a sciaenid have been discussed with supporting evidence from data on other fishes.