New research from the University of St Andrews has found that the social spread of group bubble-net feeding amongst humpback whales is crucial to the success of the population's ongoing recovery.
Bubble-net feeding is when a group of whales work together to blow clouds of bubbles that corral their small fish prey schools into higher densities that they can then engulf together. It is a cooperative and highly social behaviour that requires whales to learn how to work in a group.
The study published today (Wednesday 21 January) in Proceedings of the Royal Society B shows that the recovery of humpback whales in the northeastern Pacific depends not only on population size, but on the spread of a culturally learned feeding behaviour across the whales' social networks.
The bubble netting tactic has been seen for decades in the waters of Alaska, however, as the Canadian Pacific population of humpbacks has recovered from whaling, it is now spreading into that population too.
Researchers from the Sea Mammal Research Unit (SMRU) at St Andrews found this is likely because immigrant whales have brought the knowledge of the technique with them, thereby introducing it to whales in Canadian waters that either didn't know or had lost the knowledge of the technique.
The research was conducted in Gitga'at First Nation territory, within the Kitimat Fjord System of northern British Columbia, Canada. It's an area that has been stewarded by the Gitga'at First Nation for millennia and is known for its ecological and cultural importance. By analysing long-term social network data, the study shows that the spread of this behaviour is tightly linked to whale social structure, with knowledge passing through key individuals and groups.
Whilst the evolutionary importance of importing of new ideas is well known in human societies, this new study shows that it can also be important for whales.
Lead author from the University of St Andrews Dr Éadin O'Mahony, said: "Bubble-net feeding isn't just a foraging trick, it's a form of shared knowledge that strengthens the resilience of the entire population,"
She added: "Species recovery isn't just a numbers game, as the number of whales fluctuates, the distribution of cultural knowledge within the population may determine how well they adapt to change. Cultural loss can be just as damaging as population loss and potentially just as hard to restore. Protecting areas where distinct learned behaviours are concentrated could deliver conservation benefits that ripple far beyond local waters."
Co Author Dr Luke Rendell, Reader in the School of Biology from the University of St Andrews, said: "This study reinforces our growing understanding that the flow and spread of information in animal societies is a vital part of their ability to thrive"
The study underscores the growing need to integrate animal culture into marine management, particularly as human impacts on ocean ecosystems intensify.
