A simple method of analysing the polymodal frequency distributions of fish egg dismeters andits application to the ovarian eggs of Japanese common mackerel

A computerized simple method of analysing the polymodal frequency distributions of fish egg diameters is presented. The basic algorithm to discover some significant peaks and troughs depends on increase or decrease of the frequency between two successive egg diameter classes. A peak is counted when two increases occur consecutively and followed by two consecutive decreases. A trough is recognized in a similar manner. For complicated form of distributions,the basic algorithm is modifed and more detailed criteria are developed.The ovarian eggs of Japanese common mackerel were examined by this method. Of the ovaries 95% had from one to six peaks. In the frequency distribution of ovaries at the most advanced stage, there appeared a discontinuous space(DS) in which no egg existed.The DS divides the distribution into the developing egg group and the hydrated egg group. This simple method lacks mathematical strictness but is fairly useful and affords easy analyses of distributions of fish egg diameters