Effect of sample volume and population density on precision of larval population estimates

In aquaculture, accurate sampling and counting procedures are essential to determine precisely the number of animals in culture, to develop feeding regimes and water exchange rates, and to calculate the survival rates. Volumetric sampling techniques were applied using Artemia for the determination of the precision of larval population density estimates. By a descriptive distribution frequency of Artemia nauplii and adults counted in different sample volumes, we noted the variation decreases significantly with increasing sample volume, although no significant differences were seen in the means of the sample counts in different volumes. For precise direct counting of fish and shrimp larvae, we suggest selecting sample volumes yielding 30 to 80 animals per sample. Using this relatively large number of animals per sample allows using less replicates to achieve the desired standard error.