Humpback whales are amongst the biggest known mammals on Earth, weighing in at around 36.000kg, but by the early 1960s, after 34 million years on this planet, these gentle, majestic giants had been hunted almost to extinction. With their populations now in partial recovery, it is once again possible to find humpback whales around Rurutu in Polynesian waters. They congregate here between July and November to give birth to a new generation, and to mate. The newborns are prepared for a life of migration, covering thousands of kilometres every single year.

Dr Michael Poole, Director of the Marine Mammal Research Program at Moorea in French Polynesia and Dr. Cecile Gaspar are trying to establish a comprehensive photographic cataloguing system of the whales that should enable close monitoring of this fragile population. Until now, the identification of individuals has been restricted to working from above water and identifying the whales according to the markings on their tail fins.

Identifying whales from the water surface is extremely limiting: not only is it reliant on the whales lifting their fins clearly visible out of the water, but it also only supplies partial information. Skin patterns on heads and undersides, as well as the whales’ sex, age and behaviour can only be recorded below the water surface. A ban on scuba-diving is partly responsible for the current researchers’ approach, as well as the fact that the whales can be highly intolerant of divers in the water.

Frederic’s fotos and recordings of individual whales’ behaviour and physical characteristics allow Dr Cecile Gaspar to form a more accurate assessment of the humpback whale population around Rurutu, their movements and interactions. How big is it, and do individuals return every season or is there a change in the population’s make-up from one year to the next?

The overriding question is if the whales in this area are particularly threatened as a result of being an isolated population, or if they are able to recover from the loss of individuals when new whales join their groups. Finding answers to these questions would have a ground-breaking impact on the way these whales are protected from over-exploitation by humans.

Dr Poole calls Fred to Moorea island to see if the whales behave differently around a freediver like Frederic, who dives without the aid of oxygen tanks or rebreathers and moves like a fish. These whales are so shy, that Dr Poole expects their behaviour not to change noticeably around a noiselss diver like Frederic – they won’t see him as an unwanted intruder.

To gain the whales’ trust and be able to approach them intimately, Frederic has to stay with them underwater for as long as possible in depths of up to 50 metres. This takes an incredible amount of skill and stamina even for an extremely experienced freediver like Frederic, not to mention the risk of staying underwater at such depth for long periods of time.

Christian has to follow him with added sensitivity, both to avoid spooking the whales, and to follow Frederic’s lead at all times. But before they can dive, the team has to find some humpback whales in the first place … which can be extremely difficult. Local fishermen are a very important help for the researchers: they keep a lookout for humpback whales during their outings and report their findings to Fred, Christian and the team. They also add to the palette of information gained by the scientists’ observations by adding their own accounts of whale encounters.

It is likely that the whales will tolerate Frederic in their midst, allowing him to succeed where a conventional diver would most likely have failed. Frederic’s aim is to approach the whales up to arm’s length, take extreme close-up images for the researchers’ whale catalogue, and take notes on their behaviours.

But the strains of the long, deep dives take their toll – they are extremely exhausting and therefore dangerous. Christian and Dr Poole have to be careful and ensure that Frederic isn’t pushing himself too hard. The freediver is not one for giving up, but as impressive as this determination to succeed is, it can also be deadly.

Equiped with a hydrophone Frederic records the whales’ communications. This adds a further facet to the whale catalogue the researchers are piecing together, and provide a further insight into individual whales behaviour and identity. Remarkably, the whales don’t have vocal cords and produce the songs by forcing air through their massive nasal cavities. Not only that - there is evidence that their communications reach phenomenal distances of several hundred miles.

Frederic’s involvement in Dr. Poole’s and Dr. Gaspar´s humpback whale research project, and Christian’s ability to record Frederic’s work underwater, finally allow a thorough assessment of the humpback whale population around Rurutu and give a vital indication of just how healthy and robust this population is.