Humpback whale  (Megaptera novaeangliae)

The humpback whale is classified as Least Concern (LC) on the IUCN Red List (1). Listed on Appendix I of CITES (4), and Appendix I of the Convention on Migratory Species (CMS or Bonn Convention) (5). The Arabian Sea subpopulation and the Oceania subpopulation are classified as Endangered (EN) on the IUCN Red List (1).

The magnificent humpback whale (Megaptera novaeangliae) is renowned for its impressive leaping displays and for the mysterious 'singing' of solitary males. The robust body is blue-black in colour, with pale or white undersides (6). The flippers may also be white and are the largest appendage of any animal; reaching up to five metres in length (2). On the underside of the mouth are 12 to 36 throat grooves, which can expand when filtering water during feeding (3). Humpbacks have characteristically knobbly heads, covered in many raised lumps ('tubercles') and barnacles (6) (7). There are two blowholes on the back and the spout of water can appear very bushy (6). The spreading tail flukes have a distinct indentation in the middle (8); as the whale undertakes a deep dive it usually arches its back (hence the common name) so that the tail flukes are raised above the water and clearly visible (7). The pattern on the underside of the flukes is unique and can be used to photo-identify and track individuals (3).

Found throughout the world's oceans, humpback whales undertake yearly migrations of thousands of kilometres from summer feeding grounds in polar waters to winter breeding grounds near to the tropics (7). Indeed, individuals feeding south of Cape Horn undertake the longest known migration of any mammal, in order to breed in the warm waters off Columbia and Costa Rica (3).

Humpback whales are found in both tropical and polar areas depending on the season and are associated with shallow, coastal waters (7).

Humpback whales are baleen whales; they have large, sieve like plates of baleen (a similar material to human hair or nails) hanging down from the inside of their mouths which function to filter planktonic organisms from the water (2). Individuals can open their mouths widely, due to the throat grooves, and thus engulf large quantities of water (8). Humpbacks often lunge into a shoal of prey but have also been observed herding their prey into clusters or using a 'bubble net' to effectively trap greater numbers. During this process, a number of whales will circle underwater emitting a continuous stream of air which traps fish in the centre of the ring, the whales then surface up through their 'net' gorging on the contents within (2). During the summer months, humpbacks must feed intensely as they do not feed again during either the migration or the time spent in tropical breeding grounds (8).

Males compete for females directly by escorting receptive mates and aggressively defending them, their famous 'song' is also thought to be a form of courtship (8). Solitary males sing highly complex songs that are similar within a population but evolve over successive seasons (8). Calves are born after a 10 to 12 month gestation period, they accompany their mother on the return migration to polar feeding grounds, and studies have shown that individuals return to the same feeding ground consistently year after year (8). Possibly one of the best-known aspects of humpback whale behaviour is their acrobatic aerial display; the most spectacular of which is breaching, when the body of the whale may completely leave the water, returning with an enormous splash (7).

Humpback whales became one of the major targets of the whaling industry due to their coastal migration routes; it is estimated that over 100,000 humpbacks were slaughtered in the southern hemisphere alone, between 1900 and 1940 (6). Protected from whaling today, these whales are vulnerable to changes in the marine environment and are threatened by pollution and the possible alteration of fish stocks as a result of climate change (8).

Humpback whales received full protection in 1966 and have since captured the public's imagination (6). Whale watching tours to see these magnificent animals are popular throughout the world from Alaska to Hawaii and Japan to Australia (2). In the northwest Atlantic particularly, these have worked closely with scientists providing valuable photo identification of individuals that has helped to uncover some of the mysteries surrounding their impressive migration (2). Humpback whales are the most studied of the large whales but little is still known about some aspects of their behaviour and about population dynamics (9), further research and monitoring is therefore needed to safeguard these awe-inspiring acrobats of the sea.

The UK Biodiversity Action Plan for this species is available at UK BAP.

View information on this species at the UNEP World Conservation Monitoring Centre.

To help conserve this species by working in the field with Earthwatch, click here.

For more information on the conservation of whales:

• WDCS, The Whale and Dolphin Conservation Society:
  www.wdcs.org.uk
• Ocean Alliance:
  www.oceanalliance.org
• Whale Trust:
  www.whaletrust.org

For more information on the humpback whale:

• BBC Wildlife Finder:
  http://www.bbc.co.uk/nature/species/Humpback_whale