The whales that return

A year in two climates

A humpback whale’s year is split between places that do very different things. In the austral summer, many Southern Hemisphere humpbacks feed in productive Antarctic or subantarctic waters. As the season turns, they travel to warmer waters to mate or give birth. Tonga is one of the breeding areas used by humpbacks in Oceania. For an animal that can spend part of the year near Antarctic ice, a sheltered channel in Vavaʻu is one end of a journey measured in thousands of kilometres.

Tonga’s tourism authority gives July to October as the usual watching season. That range is a guide to when encounters are more likely. The whales move on their own schedules. A mother and calf using calm water, a travelling group and a lone singing male can all be at different stages of the same season.

The marks on a tail

When a humpback dives, it sometimes lifts its tail clear of the water. A photograph of the underside can show a distinctive pattern of dark and light patches, the shape of the trailing edge and marks acquired over the animal’s life. Researchers use combinations of these features to match an individual across photographs. The method can record movement without putting a tag on the animal.

Claire Garrigue and colleagues compared catalogues from several Pacific regions, with hundreds of identified humpbacks. Some matches linked Tonga with New Caledonia. Others linked Tonga and the Cook Islands. Each match documented an individual using more than one region. The matches did not amount to a route map for every whale. They revealed connections that were easy to miss if each island group kept only its own catalogue.

Calves, songs and the need for quiet

A calf is already several metres long at birth, yet still depends on its mother for milk and protection. Mothers and young calves often stay close to each other. A surfacing pair may be taking breaths, resting or moving on. A quiet encounter gives the animals room to do whichever of those things they were already doing.

Male humpbacks produce elaborate songs. A sequence has repeated units, and the shared patterns in a population can change over time. Singing is one reason the breeding grounds are also an acoustic place. Above water, a person sees a patch of ocean and a boat. Below it, sound travels well beyond the small area visible from the deck. Vessel traffic is part of what whales experience in waters they use for breeding.

What a good sighting can be

The study of whale watching in Vavaʻu treats boats, guides and whales as part of the same encounter. The aim of responsible observation is to avoid changing the animal’s course or taking away the quiet space a mother and calf need. A blow in the distance or an unhurried dive can be a complete sighting. It does not have to end with people in the water.

Tonga regulates commercial encounters with whales. If you are planning to go, check the latest rules with Tonga’s tourism authority and use an appropriately licensed operator. Ask how the crew decides when to back away or leave an animal undisturbed. The old Royal Sunset pages also advertised whale trips. Those offers belong to the resort’s past. Today’s observations take place through arrangements on other islands and depend on the whales and the sea that day.

There is a historical change behind that way of meeting a whale. Nearshore whaling continued in Tonga into the 1970s. A royal decree in 1978 was followed by the Whaling Act in 1979. The International Whaling Commission records commercial watching in Vavaʻu as a later development. For local boats, the same animals that once represented a catch became the focus of a different kind of work.