(ii) Modal class Progression Analysis (MPA) using Bhattacharya's method , and included in the FISAT II program , allowed to split the observed length-frequency distribution in distributions of distinct cohorts and thus to estimate their mean lengths at (relative) age.
The length-frequency analyses do not allow one to know accurately the age that corresponds to each modal class estimated.
Therefore, the modal class of ~9 cm in May estimated in this study should correspond to the age group 0.
[d.sub.1] is the first difference: the frequency in the modal class minus the frequency in the preceding class,
We can identify the modal class by inspection since it has the largest frequency.