Krill(Euphausia superba)represents an indispensable link of many marine antarctic food webs and hence proposals for a massive expansion in the exploitation of this protein source must be examined with great care. The author reviews the known data on the life cycle of krill and concludes that water density variations and its circulation are the most important factors controlling its distribution and numbers. While it is generally established that the life span ofEuphausia superbain the ocean is of the order of 2½‐4 years the author suggests that it may well be longer under ideal circumstances. However, since, after spawning, the krill is carried down to abyssal depths by the descending water at the Antarctic Convergence it is rarely given the opportunity to achieve its maximum potential age. It is further suggested that this point in the life cycle, i.e., after spawning and before the downwards plunge at the Antarctic Convergence would be the optimal point for intense exploitation since it would have minimal impact on krill stocks or on the other components of the marine biocenosis.