Humpback whales often make seasonal migrations across thousands of miles of ocean. There are many distinct humpback populations around the world and they can be found in all the world’s oceans and in both Northern and Southern Hemispheres.
The population we were studying were the Eastern Australian humpback sub-stock, part of the wider southwest Pacific population. The huge mammals travel from the cold waters off Antarctica where they feed on food such as krill, to the warm and calm waters within the Great Barrier Reef to breed and give birth.
The history of this population is one of tragedy as well as resilience. After traditional whaling in the 18th and 19th centuries, followed by the highly efficient “scientific” whaling by Russia in the 20th century, there were only an estimated 200 whales left from an original number of around 30,000. However since whaling pressure was reduced in the 1970s their numbers have grown exponentially to an estimated 30,000 (similar to their historic numbers), and their numbers are still increasing. Other populations in the southwest Pacific have not been able to rebound so quickly and in some areas their continued existence into the future is uncertain.
Working with the Blue Planet Marine team (BPM) aboard the vessel Flying Fish V I was able to learn first-hand how to collect scientific data from humpbacks. This included:
• How to spot humpback whales and identify their behaviour from a distance (exhalation, breaching, pectoral fin and fluke slapping etc.)
• How to take high quality identification photos of dorsal fins and tail flukes which are used to identify individuals
• Learning how to determine the social structure of a pod (ie mother and calf, male “escorts”, a competitive pod of males chasing a female, and so on).
• Learning how to take biopsy (DNA) data, which includes retrieving sloughed skin (dead skin which whales leave on the surface of the water), and taking live tissue samples, which requires firing a small dart which collects a small amount of tissue from the whale
• Recording underwater whale song and other social sounds through use of a hydrophone.
The biopsy data is useful for building our understanding of humpback whales for a number of reasons, but one of special interest for us in the Cooks is trying to identify whether the whales in the EAH sub-stock have genetic overlap with the sub-stocks which visit the South Pacific.
Some whale researchers believe the whales which visit the GBR may also be a part of the sub-stocks which visit the South Pacific islands including Tonga, Niue, and the Cook Islands.
Thanks to the BPM team for having me on board during the six days, and for teaching me so many crucial skills for marine mammal research. Thanks also to the International Fund for Animal Welfare (IFAW) for covering the costs of my participation on this research project. I have learned a lot about humpbacks and marine mammals in general and look forward to being able to use these skills I have learnt again in the future here in the Cook Islands, as well as better advocate for the wellbeing and conservation policy for marine mammals here in the Cook Islands as well as the wider Oceania region.