Currently my research project is focus more on fecundity aspect of Macrobrachium rosenbergii. The research main objective is to find the comparison value of potential fecundity form the target locations. However, my main concern now is how much individual sample that I should take off? Should it be more than 30 individual sample?
In tropical conditions, assuming that each berried female available is capable of producing enough eggs to provide 20 000 viable stage I larvae, you would need about 50 berried females for each larval cycle of a hatchery using a total larval tank volume of 50 m3 (e.g. ten 5 m3 tanks) producing a total of 500 000 PL per cycle (this also assumes a larval survival rate of 50% to metamorphosis).
Thanks for the respond, that will be help to cover for my potential broodstock fertility aspect.
You should be looking at the potential (ovarian) versus the actual (berried) fecundity, the latter being the number of eggs that are actually carried. I think it is important to compare at least 20-30 individuals throughout a size range, as egg carrying capacity would be expected to increase with size. A paper below has some methods.
Article Life History and Reproductive Biology of the Gilgie, Cherax ...
If this species Macrobrachium rosenbergii is quite abundant and frequent in the considered sampling sites, a sample of 30 individuals within each site is necessary. But if the species is not abundant or rare you can reduce the sample (less than 30) but all samples must be homogeneous to make an acceptable comparison.
Thanks for the knowledge Prof M.M.Kraiem. I also got another question for you.
To done the fecundity aspect i had used the gravimatric method because of the accuracy value. The question is how much minimum value in gram that i should use to count? Does this method actually have no limit value of gram to count the eggs? And of course the more gram value is the better. FYI, I had been setting that my sub-sample is should not be less than 0.1 g.
For the gravimetric method, I think firstly you need to take three sub-samples in different parts of the ovary: the upper, the middle and the lower part; because the eggs size is different. So if you take 0.1 g for each sample it will be representative.
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