A review on the feeding conditions of the baleen whales in the Southern Ocean

Food habits of the southern baleen whales were reviewed being based on the published and unpublished data since 1946. Past geographical distributions of the krill in the whales stomach revealed that the frequency occurrence by krill size showed that the large krill(>50mm) occurs more frequently in the whaling Areas II and III, then the size comes medium (40-50mm) in the Areas IV and V, and finally small krill (<40mm) frequents toward the whaling Areas VI and I. Supposing some 76 xl0 4 minke whales feed mainly in the ice-associated southern latitudes, them the past feeding grounds in the whaling Areas II and III would be beneficial for the feeding of blue, fin, humpback, and for some right whales, because the region may not be disturbed by the feeding of minke whales. No clear evidence suggesting any inter- and/or intraspecific competitions for food is known hitherto. However, high density of minke whales can be speculated to be a most possible causation of interfering the feeding of blue whales through unfavourable disturbances of krill swarms by their frequent feeding. More process-oriented in situ observations relating to behavioral relationships among baleen whale species are needed especially in the Weddell Sea area before drawing any conclusions.