Giant Beaked Whales: Berardius bairdii and B. arnuxii

Abstract

This chapter discusses the characteristics, taxonomy, distribution, abundance, and ecology of giant beaked whales, or Berardius bairdii and B. arnuxii. These two species are the largest members of the family Ziphiidae. Currently recognized morphological differences between the two species are slight and limited to smaller adult size in Arnoux's beaked whale (8.5–9.75 m vs. 9.1–11.1 m) and possible differences in flipper size and in the shape of nasal bones and vomer. Condylobasal lengths of skulls of adult Arnoux's beaked whales range from 1174–1420 mm, and those of Baird's beaked whale are 1343–1524 mm. Arnoux's beaked whales inhabit vast areas of the Southern Hemisphere outside of the tropics, from the Ross Sea at 78°S to Sao Paulo (24°S), northern New Zealand (37°S), South Africa (31°S), and southeastern Australia (29°S). Baird's beaked whales inhabit the temperate North Pacific and adjacent seas, mainly deep waters over the continental slope. The northern limits are at Cape Navarin (62°N) in the Bering Sea and in the central Okhotsk Sea (57°N), where they occur even in shallow waters of 200–1000 m. On the American side they usually occur north of northern Baja California (30°N), but there are records from La Paz (24°) in the southern Gulf of California. The southern limits on the Asian side are at 36°N on the Japanese coast in the Sea of Japan and at 34°N on the Pacific coast. They occur year-round in the Okhotsk Sea and the Sea of Japan, including the drift ice area of the former. A vagrant was taken off the Chinese coast (30°N).