How many krill should we measure?

We have no standard as to how many krill we should measure to obtain reliable estimates on its body length distribution. Krill samples collected from layers in the northern waters of Livingston Island were used in this study to get fundamental information on this problem. Based on the measurements of 2000 animals per sample, comparisons were made in mean body length and cumulative frequency distribution with less number of measurements. Measurements on 50 animals seem enough to obtain reliable estimates on mean body length. At least I000 measurements are desirable to get reliable estimates on cumulative frequency distributution.