Just a few decades ago, before the international ban on whaling in 1985, the planet’s humpback whales were teetering on the edge of extinction. However, since the moratorium was put in place – and most countries, with a couple of exceptions, have stuck to it – population numbers have been climbing back up. Now, new research has found that a population of humpback whales in the western South Atlantic has rebounded from the brink of extinction in quite an extraordinary way.

Reporting in the journal Royal Society Open Science, a team from the University of Washington estimates that the population of South Atlantic humpbacks (Megaptera novaeangliae) has now soared to around 25,000 individuals, around 93 percent of their pre-whaling numbers.

Commercial whaling in the past couple of centuries slashed the western South Atlantic population of humpbacks dramatically, reaching a critical 450 individuals in the 1950s. In fact, it’s believed around 25,000 whales were killed in just over 12 years in the early 1900s.

Towards the end of the 20th century, researchers realized that the species was in grave trouble, eventually resulting in the International Whaling Commission’s (IWC) moratorium on the commercial hunting of all whale species in 1986. 

A previous survey by the IWC assessed the health of this population between 2006 and 2012, concluding that the population had only recovered 30 percent of pre-whaling numbers. This new study, however, has used a more extensive methodology – involving air and ship surveys along with advanced modeling techniques – and found their work massively underestimated the marine mammals' comeback.

"We were surprised to learn that the population was recovering more quickly than past studies had suggested," John Best from the University of Washington's School of Aquatic and Fishery Sciences explained in a statement.

"Accounting for pre-modern whaling and struck-and-lost rates where whales were shot or harpooned but escaped and later died, made us realize the population was more productive than we previously believed," added co-author Grant Adams.

Bear in mind, however, the western South Atlantic humpbacks are just one of seven Southern Hemisphere breeding groups in the world’s oceans. 

The resurgence of the species in the area is expected to have numerous ecosystem-wide impacts. For example, krill are also moving further to the poles as a result of climate change. This could result in the whales coming into more competition with other predators, like penguins and seals, for whom krill is also their primary food source. 

Nevertheless, this is very good news, providing clear evidence of how an endangered species can spring back from near extinction given the right policy changes, collective action, and management.