Abstract: Antarctic krill (Euphausia superba) population age structure was determined using the Bhattachaya method, with data on compound eye diameter and body length taken from krill collected from Prydz Bay between February and March 2013. Of four apparent age groups, the most dominant was 2⁺, with eye diameter measurements better differentiating age cohorts than body length. Average eye diameter of 1⁺–3⁺ krill ranged 1.21–1.40 mm, 1.59–1.76 mm and 1.93–2.08 mm respectively, with those of 4⁺ krill being approximately 2.23 mm. Since the 1980s, body-length characteristics of Antarctic krill have remained stable, suggesting krill resources around Prydz Bay have not been over-explored.

Key words: Antarctica krill, Prydz Bay, eye diameter, body length, Bhattachaya method, maximum likelihood function