Following Humpback Whales

The monitoring of humpback whales has provided new information on the ecology of these animals.

The PMBS was a pioneer in revealing the migratory routes and destinations of whales that reproduce in Brazil and determined that they migrate from the southern portion of the Abrolhos Archipelago and use ocean waters away from the coast during their journey to feeding grounds in the Antarctic Ocean. In addition, the project found that routes almost did not vary over the years; thus, these routes are used consistently by different animals. Another important finding of the project was that whales are capable of maintaining relatively constant courses for hundreds of kilometers during migration, suggesting that these animals have a sophisticated navigation system.

The feeding grounds of humpback whales that reproduce in Brazil were unknown before investigations using satellite telemetry. The first animals marked and monitored by the project showed that these whales travel to remote areas near the South Georgia and South Sandwich islands in the southern Atlantic Ocean. These areas have high productivity of Antarctic krill, a small planktonic crustacean that is the primary food of humpbacks in the Southern Hemisphere. The discovery of the feeding grounds of Brazilian whales also showed that this population was the first to be affected by industrial hunting in Antarctica. The first whaling stations were established in the early 20th century in the South Georgia, and over 25 thousand animals were killed in this region in less than 10 years. This resulted in a 95% population reduction and virtually decimated Brazilian humpback whales.

In 2012, the PMBS introduced the use of satellite transmitters that not only record the position of the whales but also sample environmental and diving behavior data. Using these transmitters, the project was able to provide novel descriptions of whale behavior during migration between Brazil and their feeding grounds. The results were fascinating. One of marked whales dove to depths of 350 m immediately after beginning migration. Such deep dives are unusual for plankton-feeding whales and the causes are not yet understood; however, it is possible that the animals are searching for food to meet metabolic needs during high-energy demand periods such as the migration.

PMBS data have also provided information for population assessments and habitat descriptions for the development of oil exploration and production in Brazil. A study conducted in two of the most important oil and gas exploration areas, the Espírito Santo and Campos basins, described critical habitats surrounding these areas and is expected to encourage relevant government agencies and industry to explore less environmentally sensitive areas.