This paper examines the size structure of populations of E. superba in relation to their habitat, on the basis of an analysis of data collected by the author during the 1981 season in the region of the Antarctic Peninsula and the South Shetland Islands, as well as data collected by other researchers during FIBEX and data from earlier literary sources.

The paper addresses the question of whether size groups of E. superba correspond to age groups. It is shown that the size groups of krill are not a seasonal phenomenon, but correspond to a certain extent to sets of specimens which hatched at the same time and developed under similar conditions. Hypotheses are formulated regarding the age and growth of E. superba; in addition, data are cited on the growth rates of krill in relation to feeding conditions, temperature factors and other biotic and abiotic factors.

Possibilities are outlined for the elucidation of the problem of the age and size structure of E. superba through the study of genetic, morphological and physiological uniformity of krill both within and between size groups.

Clarification of the question of population age structures of E. superba can be achieved through the comparison of results of studies of spatial and temporal variability in the size composition of krill, modelling of growth under various conditions and physiological and chemical research.