Sexual regression,shrinkage, re-maturation and growth of spent female Euphausia superba in the laboratory

Live female Euphausia superba, Dana were collected from Prydz Bay, East Antarctica in January 1985, and observations of intermoult period, growth and maturation changes were made on individuals which spawned and were subsequently maintained in the laboratory for 12 mo. Over this experimental period an instrinsic cyclic reproductive pattern was observed. Following spawning, there was a regression of the female copulatory organ, the thelycum, coupled with a decrease in body length and an increase in the krill's mean intermoult period. This was followed by a period of sexual re-maturation, associated with positive growth and a decrease in the mean intermoult period. This study indicates multi-year spawning of E. superba and a life-span greater than 4 yr.