It had been nearly two centuries since the Brazilian coast had seen so many humpback whales. A study released by the Instituto Baleia Jubarte estimates that the species is recovering and that around 25,000 of them passed through the country in the second half of 2022. The number is close to the approximately 27,000 to 30,000 specimens counted 200 years ago.
The advantages of recovering this whale population go beyond the complete removal of the risk of extinction, with the end of hunting. These mammals contribute to the fight against climate change.
The reason for the growth, for specialists, is basically a reflection of the end of hunting, prohibited in 1966, a period in which the population was reduced to less than 5%, something between 600 and 800 individuals.
“It was no longer economically viable for ships to go out to hunt humpbacks, because the chance of finding them was very small”, says veterinarian Milton Marcondes, research coordinator at the Baleia Jubarte Project.
The killing continued for a few more years, even if banned, until it ceased to actually occur in the late 1970s.
The end of hunting, associated with measures such as the reduction of being run over by boats and accidental entanglement in fishing equipment, created conditions for an increase in the number of whales of this species.
The growth of the humpback population in Brazil is close to stability, according to the researcher. The challenge now, he says, is to find a way for whales to coexist with human activities, such as those in the oil sector, so that they do not disturb these animals.
One focus is adapting the timing of oil drilling operations that are harmful to whales. “We made a recommendation that was accepted by Conama to restrict in Bahia, Espírito Santo and Sergipe from July to November, when the humpbacks are there, up to 500 meters deep”, he says.
Humpback whales pass through Brazil between winter and spring to mate. They arrive, therefore, in June and remain until October and November, when they make their way back to the sub-Antarctic waters, in the south of the planet.
During the period they are here, they are counted every three years by the institute through aerial sightings. The professionals fly over an area that goes from the border of Rio Grande do Norte and Ceará to the north coast of São Paulo, advancing inland to where the depth reaches 500 meters. Through sophisticated calculations, they estimate the total, including those submerged, based on what they can see.
The first estimates are from the end of the 1980s, according to Enrico Marcovaldi, one of the founders of the institute. At the time, without the same current research conditions, they calculated around 500 humpbacks in the region.
In 2003, via aerial sighting, an estimated 3,660 individuals were estimated, and in 2019, the number already reached 16,000. It was based on the results of this monitoring that, in 2014, the humpback whale was removed from the list of endangered species.
CO₂ and fertilizer retention
As whales are animals that grow a lot, they retain a lot of CO₂, one of the biggest villains of global warming and, consequently, climate change.
“Whales are of fundamental importance for the planet in the same way that forests are important, because they retain a lot of carbon dioxide and help to control the climate”, says Marcondes.
According to a study carried out by economists from the IMF (International Monetary Fund) and the universities of Duke and Notre Dame, a whale can retain up to 33 tons of carbon dioxide during its lifetime and, when it dies, it sinks into the oceans taking with it all this CO₂.
A tree stores approximately 50 pounds a year. “A healthy and large population of whales retains a lot of CO₂”, says Marcondes, adding that a humpback whale reaches 35 tons and can live around 60 years.
Another way that humpbacks help the ecosystem is by fertilizing the tens of thousands of kilometers of ocean they travel through.
Feces, explains the researcher, are rich in iron and nitrogen, in addition to urine, which is also rich in nitrogen. “This causes the plankton, the algae, to proliferate. And the algae release oxygen into the atmosphere and remove CO₂.”
The entire cycle is favored, as krill, the crustacean that is the whales’ main food, eats these algae. In this way, the whale helps in the proliferation of the food of its food.
The Planeta em Transe project is supported by the Open Society Foundations.
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