Text written by Livia Gavard and Fanny Dessard, who followed Dr Pierre Gallego to Mozambique to study humpback whales in collaboration with Underwater Africa.
Pierre, Manon, Fanny, Livia, and a volunteer, Diane, are currently in Tofo, Mozambique, where humpback whales aggregate every year to reproduce. Within the context of Pierre Gallego’s PhD project on humpback whales, the field work focuses on:
- Taking photo-identification (photo-ID) pictures of the unique pigmentation patterns on the ventral side of the fluke to identify as many individual whales as possible and follow the individuals over time.
Over 2 weeks, 14 individuals have been identified.
- Taking biopsies, which are small samples of skin and blubber which are used for studies on genetics, pollutants and stable isotopes. For instance, it is possible to determine the sex and age of the animals by analysing the DNA of the skin sample, which is not possible to determine from visual observations from the boat. Stable isotopes can be used to study the diet of the animals and the location of the feeding grounds off Antarctica.
Over 2 weeks, 27 biopsy samples have been collected, which as the total number of samples taken last season! So we are off to a good start to reach our goal of 60 biopsy by the end of September.
A typical day at sea starts by locating a group of humpback whales, we note their position using a GPS, observe their behaviour from the distance, and take photo-ID pictures. If they are resting, we record their songs using an underwater microphone, or hydrophone. Only male humpback whales are known to sing and their song can evolve during the season. Then we attempt to get biopsy samples.
Among all the days spent at sea so far, 2 days stand out when humpback whales were breaching all around our boat. It is thought that they jump to communicate with each other, to compete against other males for a female, or to get rid of parasites. We have also seen several humpback whale calves, which are considerably smaller than their adult counterpart, and had the chance to swim with whale sharks and bottlenose dolphins!
Locally, we collaborate with the team of Underwater Africa, which is composed of 4 team members and volunteers.
- Emily works on microplastics and plankton.
- Raph help local people to develop aquaculture.
- Calum works on his PhD on hammerhead sharks.
- Gabriel is in charge of the collaboration with the government and local communities.
In our spare time, we help them with their projects. They have for example established a protected area in the mangroves. We have placed signs and buoys to mark the area and work along with the local community to organise patrols to stop illegal fishing. Sometimes, we just observe the whales from the tip of Tofinho with binoculars and a telescope. Livia and Fanny have had the opportunity to take their PADI Open Water course and more dives are planned in the near future.