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How far do whales swim for lunch?
Each winter more than 16,000 South Atlantic humpback whales gather off Brazil’s coast to mate and bear their young. In summer they migrate to feeding grounds. A unique research programme uses satellite tagging to discover the route whales travel – information that could help to better protect these giants of the deep.
Just off Brazil’s central coast, an inflatable speedboat follows a pod of humpback whales. In the bow, harnessed against the ocean chop, a marine scientist waits, eyes fixed on the water. A towering vapour cloud signals one of the 40-tonne beasts has surfaced. The great black arch of its back glides past and the scientist sees his chance. Using compressed air, he launches a transmitter dart, aiming just ahead of the small fin that gives the humpback its name. The tiny device buries, unnoticed, in the thick blubber with just a small antenna visible.
For the next eight months or so, whenever the whale surfaces, the transmitter will report its position and how deep it dived to an orbiting relay satellite.
The scientist is part of a team in the whale-monitoring programme run by Brazilian science non-profit Instituto Aqualie and supported by Shell Brasil to learn more about humpback whales.
Safety in numbers
Along with many other whale species, South Atlantic humpbacks were hunted to near extinction in the 19th and early 20th centuries. Their numbers have slowly recovered since gaining international treaty protection in the mid-1960s. Still, through the end of the last century, very little was known about the Brazil population – other than that they were seen off the coast every winter.
Over the last decade the team has tagged, tracked and studied more than 120 Brazilian humpbacks. This is the longest-running humpback whale tracking project anywhere, according to Dr. Alex Zerbini, Instituto Aqualie’s science director.
”The programme has not only revealed important information about their movement, migration, breeding and feeding behaviour,” says Alex. “It’s also developed satellite tagging methods now used by scientists throughout the world.”
The transmitters have shown, for example, that the whales are able to navigate more than 3,700 kilometres (2,000 nautical miles) of open ocean between Brazil and their summer feeding grounds in Antarctic waters of the south Atlantic. They do this in a nearly straight line with no visible reference points, apparently following the same route every year.
Secrets of the deep
Transmitter-tagged mother Humpback whale with her calf swims off Brazil’s coast
The studies also found the whales tend to hug the coast off Brazil, staying in shallower waters over the continental shelf.
“Tracking has defined previously unknown critical habitat for the whales,” says Alex. The information gathered allows regulators to expand and tailor protection zones to limit the impact from pollution caused by agricultural and industrial activities on land, as well as shipping, fishing and oil exploration during the whales’ stays in Brazilian waters. It also helps Shell and others plan their activities around the whales’ movements.
Shell has been the project’s exclusive sponsor from the beginning. It had just returned to Brazil exploration and production when the project was beginning in the early 2000s.
“The research team was attracted to Shell as a sponsor for its extensive offshore experience and long commitment to sustainability,” says Alex. ”And, in Brazil, Shell is identified with advanced technology through its fuels and lubricants products.”
Shell also helped Instituto Aqualie in developing high safety standards for the programme and its equipment.
“Our support reflects the importance to us of environmental preservation and scientific knowledge,” says Shell Licensing & Environment Manager Brazil, Anídio Corrêa. “We continuously look for ways to minimise potential impacts from our activities in the region."