Blue whales, the world’s largest mammals, are getting back to Spain’s Atlantic coast after a shortfall of over 40 years.

The first was spotted off the coast of Galicia in north-west Spain in 2017 by Bruno Díaz, a sea life researcher who is top of the Bottlenose Dolphin Research Institute in O Grove, Galicia.

Another was seen in 2018, another the next year, and afterward in 2020 the two of them returned. A little more than seven days prior an alternate specimen was sited off the Islas Cíes, close to O Grove.

Díaz said it was not yet evident whether the environment emergency was leading the animals to change their habits and return to a space where they were pursued nearly to extinction.

“I believe the moratorium on whaling has been a key factor,” he said. “In the 1970s, just before the ban was introduced, an entire generation of blue whales disappeared. Now, more than 40 years later, we’re seeing the return of the descendants of the few that survived.”

There was a centuries-old whaling industry and twelve whaling ports in Galicia. Spain didn’t boycott whaling until 1986, by which time the blue whale was everything except wiped out in the district.

Be that as it may, not every person considers the whales’ return as good news.

“I’m pessimistic because there’s a high possibility that climate change is having a major impact on the blue whale’s habitat,” Alfredo López, a marine biologist at a Galician NGO that studies marine mammals, told the newspaper La Voz de Galicia.

“Firstly, because they never venture south of the equator, and if global warming pushes this line north, their habitat will be reduced. And secondly, if it means the food they normally eat is disappearing, then what we’re seeing is dramatic and not something to celebrate.”

Díaz theorizes that the animals may likewise have gotten back to Galicia out of a type of homesickness, or ancestral memory.

“In recent years it’s been discovered that the blue whale’s migration is driven by memory, not by environmental conditions,” he said. “This year there hasn’t been a notable increase in plankton, but here they are. Experiences are retained in the collective memory and drive the species to return.”

Analysts accept this kind of people memory, or cultural knowledge, exists in numerous species and is key to their survival.

A typical blue whale is 20-24 meters in length and weighs 120 tons – comparable to 16 elephants – however specimens of up to 30 meters and 170 tons have been found.