By Vanessa Mignon

Every year, between July and October, Humpback whales (Megaptera novaeangliae) migrate to Tonga, in the South Pacific, to mate, give birth and nurse their young in the warm waters. During that time it’s possible to swim with these gentle giants under specific regulations.

I have been very fortunate to guide tours with the whales for years, and still to this day I am continuously amazed by the charisma and level of consciousness of those animals. When we get in the water with them, they clearly look back at us and acknowledge our presence, before deciding to swim away or stay. 

One of the most humbling experiences, in my opinion, is when a mother allows us in the water with her calf. The bond between them is strong, intimate and very tender. I have seen mothers support their newborn at the surface to help it breath, and calves cuddling under their mum’s chin as if looking for shelter and reassurance. I have witnessed the touching moment when a mother holds her calf in her pectoral fins and slowly caresses it. And I have met protective mums positioning themselves between us and their calves making it clear that they are not comfortable with swimmers around them.

Each calf is unique in appearance and in personality. Some are shy, and stay close to their mother, staring at us from a distance. Others are curious and would often come and have a close look at us. And then there are always the brave, overly confident, crazy kids who decide to chase us around, clearly unaware of their size and strength.

Every day with the whales is different. If you are lucky, you might hear the beautifully haunting song of the males, or witness the fast and often violent courtship battle, known as a “heat run”, where several males compete for a female’s attention.

It is important to understand and appreciate that swimming with whales in Tonga is a privilege. The whales travel a very long way to mate, give birth and care for their newborns. During that time, there is little to no food available and therefore the adults survive by metabolizing the food energy in their blubber. They lose a lot of their body weight during the migration and their stay in Tonga, sometimes up to one third of their total body weight. It’s even more demanding for the mothers that have to protect, nurture and feed their babies in preparation for the long trip back to Antarctica.

Humpbacks were nearly fully exterminated by whaling. It has been estimated that from 1904 to 1980 more than 200,000 humpbacks were killed in the Southern Hemisphere. Thankfully the populations have been increasing, but they are still nowhere near their pre-whaling numbers. Furthermore the Tongan population is not recovering as well as other humpback groups around the world. While the species is listed as “Least Concern” overall by the International Union for the Conservation of Nature (IUCN), “concern remains about apparently discrete and small subpopulations of humpback whales, such as the South Pacific subpopulation, for which information about their status is lacking”. Therefore it is important to ensure that any interaction with whales is respectful and done on the whales’ terms so that it doesn’t disturb their behaviour.