Biology of Finfish and Shellfish

Gravimetric method

This is based on weight of the ovary. After liberating the ova from the ovarian tissues, the ova should be thoroughly washed and spread on a blotting paper to dry in air. The number of eggs present in the each subsample can be counted using compound microscope. After counting all the eggs in the subsamples, the total number of eggs in each subsample and their weight should be pooled to find out the sample weight and number of eggs present in the sample and then the total fecundity can be calculated using the formula given below.

                                Total weight of ovary

Fecundity (F) = ________________________ x number of mature ova in subsample.

                                Weight of sub sample

                                     Total number of eggs present in the ovary

Relative Fecundity = ------------------------------------------------------------

                                                      Weight of the fish