Age determination of Antarctic krill using size, fluorescence, and image analysis techniques

The ages of 252 mature female krill, collected from Prydz Bay in January 1985, were determined using length frequency analysis and the fluorescent age pigment (FAP) technique. Results of both methods indicate 6 year classes for adult krill. Correspondence between the ages determined by the two techniques is generally within one year.
The animals were also analyzed by a computerized image analysis system, which recorded a large suite of size and shape parameters. The accuracy of discriminant functions constructed to relate the image analysis parameters to age approached 90% for the ages defined by length frequency, and 52% for physiological age.