Uncertain status of the northern bottlenose whale Hyperoodon ampullatus: population fragmentation, legacy of whaling and current threats

Abstract

The northern bottlenose whale Hyperoodon ampullatus is the best-known beaked whale species, but its conservation status remains very uncertain. A medium-sized cetacean that lives in the deeper waters of the northern North Atlantic, it is remarkable for its deep dives and inquisitiveness towards ships. There seem to have been of the order of 100 000 whales prior to 40 yr of intense whaling beginning in the 1880s, and this population was undoubtedly heavily reduced by 1920. The effects of a second phase of whaling between 1937 and 1973 are con- tentious, and current abundance estimates are patchy. There are suggestions of metapopulation structure (even at the scale of 50 km) in the western Atlantic among populations that do not appear to migrate. In the eastern Atlantic, data on population structure and migrations are few and confusing. Whales are incidentally caught in fishing gear and interact with fisheries off Labrador, Canada. They may also be affected by underwater noise. However, the population con- sequences of these and other anthropogenic stressors, particularly within this unknown metapop- ulation structure, are very uncertain. In some respects, such as the paucity of sightings on major whaling grounds off mainland Norway and Labrador, the picture that we have is disturbing. Analyses of genes, contaminants and vocalizations, as well as photoidentification and satellite tag data, can inform about population structure, migrations, life history parameters, current popula- tion sizes, and threats.