A review of the distribution, migrations, food, reproduction, exploitation and present abundance of humpback whales (Megatera novaeangliae) in the northeast Atlantic

Abstract

Most available knowledge about northeast Atlantic humpback whales (Megaptera novaeangliae) is based on information and experience gained during the pioneer period of modern whaling in Norwegian waters in 1868-1904 when almost 1,500 animals were taken. A literature review reveals that these humpbacks stayed in their northern feeding areas during most of the year (May-January), migrating out only during a short period in spring for breeding purposes. Recent incidental sightings data confirm these migration patterns. Seemingly, euphauciid crustaceans were their main prey items when they arrived in Norwegian waters (mainly in the Bear Island area) in late spring, whereas capelin (Mallotus villosus) became more and more important throughout the season when the humpbacks proceeded eastwards into the Barents Sea. The collapse in the Barents Sea capelin stock may have contributed to a reduction in these eastwards autumn migrations after 1985. The humpback's breeding migration in early spring were observed to be directed westwards from the Barents Sea and towards the Norwegian Sea, but the migration routes and the localisation of the breeding areas were and are still unknown. Between 1904 and 1955, when the humpback was given total protection in the North Atlantic, less than 50 humpbacks were caught in Norwegian waters. The number of humpbacks in the northeast Atlantic has probably never been large. Results from more extensive sightings surveys in 1988 and 1989 seem to indicate a present abundance of about 1,000 humpback whales in Norwegian and adjacent waters.