The Humpback Whale
The humpback whale (M. novaeangliae) is a species of baleen whale (Mysticeti) found in all of the major oceans of the planet. Adult humpback whales can measure 15 m in length and weigh 40-50 tons. Calves are 4-5 m at birth and are born after a gestation period of nearly one year. The calves stay with the mother from birth to weaning, which generally occurs when the calves reach one year.
These whales are called “humpback” because their back is shaped like a hump, especially when they arch their bodies to dive. The long pectoral fins are one of their main characteristics and can measure 1/3 of the length of the animal. The body is dark gray,almost black. The ventral portion of the caudal and pectoral fins varies in color and may be black, white or a combinations of the two colors in shades of gray.
The humpback is a typical migratory species. In winter and spring, these whales prefer tropical regions to reproduce, give birth and nurse their calves. During this period, they rarely feed. At the end of the season, the whales begin a long migration to polar regions where they spend summer and autumn feeding on small planktonic crustaceans or fish that form large schools. There are populations of humpback whales in both hemispheres of the planet, but they rarely meet because their migratory patterns are synchronized. The Brazilian humpback whale population is usually found along the central and northeastern coast (between Rio de Janeiro and Rio Grande do Norte) from May to December. Certain animals may be seen on the north coast (Ceará and Maranhão) or oceanic islands, such as Fernando de Noronha, and the São Pedro e São Paulo and Trindade e Martim Vaz archipelagos. The Abrolhos Archipelago, a region with important coral reefs, is the main reproduction area for the species in the South Atlantic Ocean and holds approximately 80% of the Brazilian humpback population.
The humpback whale was one of the main targets of the whaling industry in the 19th and 20th centuries. The species was protected in 1960, but poaching occurred until at least the mid-1970s. An estimated minimum of 250 thousand whales were killed worldwide during commercial hunting activities that began in 1900. After over four decades of protection, humpback whales are recovering and returning to their former habitats. The Brazilian humpback population was virtually decimated by hunting. Nearly 30 thousand whales were killed between 1905 and 1915, reducing the population to less than 5% of its pre-exploitation size. Today, the Brazilian humpback population is estimated to be at least 15 thousand, and it is still growing.
The humpback whale was chosen to launch telemetry studies in Brazil for the following reasons:
- Research on this whale was considered a priority because the humpback was considered an endangered species;
- Migratory routes and destinations of the humpbacks that reproduce on the Brazilian coast were not known before the commencement of the PMBS;
- Important migratory routes and destinations were discovered, which improved the conservation of the species;
- Humpback whales usually inhabit coastal regions, which is beneficial for research access but increases the vulnerability of the whales to the impacts of human activities;
- Humpback whales are easy to approach for transmitter attachment, and these are important characteristics that facilitate technological development and human resource training.