In 1958, you could have counted every humpback whale in the western South Atlantic and stopped at about 440. A species that once numbered in the tens of thousands had been hunted down to a rounding error.
Today, in the same waters, there are an estimated 25,000.
How you erase a giant
Before industrial whaling, roughly 27,000 humpbacks fed and bred along the western South Atlantic. Then the harpoon fleets came. Whale by whale, decade by decade, the population was rendered for oil and meat until, by the late 1950s, it sat on the edge of vanishing entirely — down to around 1–2% of its original size.
The rule that changed the story
In 1986, the International Whaling Commission enacted a global moratorium on commercial whaling. This year marks 40 years since that line was drawn. Given room to breathe, the humpbacks did something conservation rarely gets to show so cleanly: they came back.
A 2019 study led by Alexandre Zerbini (Royal Society Open Science) combined ship and aerial surveys with historical catch records and genetics, and revised the recovery sharply upward: the western South Atlantic population now stands at roughly 93% of its pre-whaling numbers.
Nearly wiped out in one human lifetime — and nearly all the way back in another. Recovery at the scale of an ocean, because we agreed to stop.
Hope, not a victory lap
It would be dishonest to end there. Not every population rebounded like this one — some are still endangered — and the harpoon has been replaced by quieter threats: ship strikes, entanglement in fishing gear, and a warming ocean shifting the krill humpbacks depend on. The work isn't finished; it has changed shape.
But the lesson is rare and real, and worth holding onto: when we decide to stop harming the ocean, the ocean can heal — quickly, and at enormous scale. That is the entire bet behind marine conservation, and the humpback is the receipt.
At Marvi Ocean, $1 from every order goes to Sea Shepherd, who work on exactly these modern threats — illegal fishing, entanglement, and defending the feeding grounds these whales fought their way back to.
Sources: Zerbini et al., Royal Society Open Science (2019), doi:10.1098/rsos.190368; Smithsonian Magazine; Science News; International Whaling Commission.