DISTRIBUTION AND ABUNDANCE OF POSTLARVAL KRILL (EUPHAUSIA-SUPERBA DANA) NEAR PRYDZ BAY IN SUMMER WITH REFERENCE TO ENVIRONMENTAL-CONDITIONS

Data on the distribution, abundance and population structure of krill in the Prydz Bay area during January-February 1985 are considered in relation to hydrography and phytoplankton standing stocks. Stratified mean density and biomass estimated for the whole surveyed area from RMT-8 hauls were among the lowest recorded (3.3 individuals 1000 m-3 and 3.1 g 1000 m-3) confirming Prydz Bay as a low krill abundance area in the Southern Ocean. Age cohorts 1+ to 4+ were present, the size of the animals increased from south to north and juveniles were mostly found in surface waters near the pack-ice. Adults were in an active reproductive phase: 98% of the females were mated and 35% were ready to spawn whereas 86% of the males carried spermatophores. Breeding was taking place in oceanic waters over deep zones with the spawning season limited to January-April. Phytoplankton biomass was also very low in the area (mean of 29 mg Chl a m-2 in the upper 200 m) and currents speed low, never reaching 10 cm s-1. Krill distribution was strongly related to water circulation pattern but not related to phytoplankton distribution.