Antarctic krill is the keystone species supporting the southern ocean ecosystems. Yet information on demographic structure of krill populations has been very limited due to highly variable growth rates and possible shrinkage during winter periods of low food. We examined the population age structure and dietary history of E. superba using cellular peroxidation products (collectively termed lipofuscins)and lipid biomarkers as part of the Southern - GLOBEC program. Sub-adult and adult krill (size (total length) ranging from 21.4 - 60.4 mm; (41.3 ± 10.7 mm, n=537) were collected from the open water areas near Adelaide Island using multiple opening/closing nets and environmental sensing system (MOCNESS). Lipofuscins were extracted from neural tissues (eye and eye-stalk), quantified, and normalized to protein content on board to allow comparisons across animal sizes. Multiple fluorescent components were observed, with the major product having a maximum fluorescence at excitation of 355nm and emission of 510nm. Lipofuscin levels of field-collected krill were highly variable, but significantly correlated with body size (r>0.4 at p=0.05). Further examination will compare field collections to reared animals of known age to calibrate the demographic structure observed in overwintering populations. Lipid markers (fatty acids, sterols, etc.) are being applied as tracers of their dietary history and linked to age information to understand feeding history. These results suggest that lipofuscin can be measured among individual krill, and can be combined with lipid markers to understand age and overwintering strategies.