Visual observations of the Antarctic sea birds during the FIBEX cruise of the KAIYO MARU

The KAIYO MARU, a research vessel of the Fishery Agency, made the FIBEX survey in the Indian sector of the Antarctic Ocean during the austral summer of 1980-1981. At the same time, visual observations of sea birds were carried out along the cruise tracks of the survey. Sea birds were observed in the area from 30°E to 85°E longitudinally and on the south of 55°S, particularly from 61°S to the ice edge. Species and number of the sea birds recognized in a ten minutes observation were recorded in the sheets prepared for these observations. The ten-minute observations were usually made every four hours, six times a day. The bird species observed frequently were as follows : antarctic petrel, white-chinned petrel, cape pigeon, light-mantled sooty albatross, prions, and so on. These birds were evenly observed longitudinally and showed a circumpolar distribution. Latitudinally, however, they showed a different distribution, though they extended to the south with the retreat of the ice edge. The distribution of these birds was also considered with the records of acoustic estimation of krill