Acoustic rediscovery of right whales in a former whaling area, the Cape Farewell Ground, between Greenland and Iceland.

Abstract

The North Atlantic right whale (Eubalaena glacialis) is one of the world’s most endangered cetaceans, with only 300–350 animals believed alive. Most right whales are thought to range from Florida to Nova Scotia, though the whereabouts of a significant portion of the population remains unknown in both winter and summer. Here we describe an acoustic survey for right whales near the Cape Farewell Ground, a late 18th-century whaling area. Continuously recording autonomous hydrophone instruments were deployed at five sites for one year in 2007–2008, after which data were analyzed by automatic detection with manual checking for “up” calls of right whales. Over 2000 calls were detected in all, with calls found at all sites but mostly from near the Cape Farewell Ground. The data are consistent with a seasonal migration northeastward toward Iceland in July–August followed by return movement later in the fall, with the last detection in December. At one site, calling occurred in the fall on 17 separate occasions, suggesting a significant number of right whales present. A right whale photo-identified in 2003 at the Cape Farewell Ground was not in the North Atlantic right whale catalog, suggesting the possibility of a previously unidentified stock.