Southern right whales are closely related to the majestic North Atlantic right whales that lucky whale watchers sometimes spot off the United States’ East Coast. But like any relatives who live far apart, the two species’ lives are very different.
Ten percent of Southern right whales are expected to live past 130 years old, based on the findings in a recent study published in the journal Science Advance. That would make these gentle giants, who thrive throughout the Southern Hemisphere, the second-longest living mammals in the world, behind only bowhead whales.
On the other hand, only 10% of the 370 or so remaining North Atlantic right whales are expected to survive past 47 and their median life span is only about 22 years, largely because human activity leads to often-injurious or fatal encounters with fishing gear and fast boats. Absent these threats, we could see North Atlantic right whales living for a century or more.
Their shortened lifespans weren’t the only sobering conclusion in the study.
The study also found that Southern right whale females give birth every three years. This means that the typical Southern right whale mom who lives for more than 75 years can deliver more than 20 calves over the course of her life. Typical North Atlantic right whale females, who die at much younger ages, would average around five calves per lifetime if they gave birth every three years after achieving sexual maturity.
But shorter lifespans aren’t the only thing affecting North Atlantic right whale reproductive success. Stressful environments also affect the fertility of North Atlantic right whales, leading to births every 6-10 years, instead of the normal interval of every three years. According to the Science Advance study, if North Atlantic right whale moms only birth calves every seven years, we can expect each mom to produce two children during her lifetime. That is substantially fewer calves than their Southern cousins.
As grim as these statistics are, they also provide some hope: If we can extend the lives of North Atlantic right whale moms and limit their stressors, they could produce enough calves to dramatically increase their species’ viability.
So why are North Atlantic right whales so stressed out?
Both the Southern and North Atlantic right whales were hunted to near-extinction during the height of whaling in the 1900s. Throughout the 20th century, 2.9 million whales of all species were killed, so it’s no surprise that both right whale species suffered. But by the 1960s, when the hunting of all right whales had been banned for decades, Southern right whales began to replenish their numbers – North Atlantic right whales did not.
Since 2017, North Atlantic right whales have been experiencing what experts call an “unusual mortality event” that has further prevented their population from recovering. Their two leading causes of that mortality are fishing gear entanglements and boat strikes. Five right whales died from these types of accidents just in 2024. Looking at the numbers since 2017, it’s even worse – 25 right whales have died due to boat strikes or entanglements, and 99 victims of these encounters with humanity remain seriously injured or in poor health. These numbers are devastating for a population already so depleted.
Another grim fact is that mothers and calves, whose lives are critical if we want to revive this population, are the most vulnerable to these accidents. Calves must stay close to the surface since they are not strong enough to dive for long periods of time, so they’re more exposed to boat strikes. Their mothers, who stick close by their babies, face the same risk. In addition, right whales move slowly, are dark in color, and lack a dorsal fin, making it difficult for boat captains to spot them.
We can only imagine the life a 100-year-old right whale would lead if it could survive so long.
To ensure the perpetuation of North Atlantic right whales, we need to reduce vessel strikes and end entanglements. If we can reverse the current, deadly trends, we can only imagine what right whales born this year would see. A 130-year-old today would have been born in the 19th Century, lived through the Great Depression, both world wars, the height of whaling, and subsequently, the banning of whaling.
How different will our world be in the mid-22nd Century – and how wonderful would it be if the right whale calves today could one day celebrate their 100th birthdays surrounded by pods of whales stretching along the whole Atlantic Coast.
