Spectacular Humpback Whale Behaviour Prior to Returning to their Feeding Grounds

Bazaruto Seascape is part of the ocean basin that is home to a considerable diversity of marine mammals. It is for a reason that in 1979 the Indian Ocean was designated as a whale sanctuary by the International Whaling Commission, and it’s been evident ever since that the decision was right and timely, as by then most of the populations of great whales were hunted to near extinction, and s a result some of the sub populations had plummeted to less than 5% of the pre-exploitation population size.

Since then, due to considerable conservation efforts of different stakeholders and governments, a gradual recovery took place. The IUCN Red List Species Data (2019) estimates the current global humpback whale population size to be 135,000 individuals, with a mature population size of approximately 84,000.

Inverted fluke slap in a sequence of actions. Photos by Ekaterina Kalashnikova. 

We are privileged to witness East African sub population of humpback whales (Megaptera novaeangliae) slowly bouncing back. Every time our team is heading out, either for a dive or an exploratory boat trip, the big wings of New England (novaeangliae is old Latin for New England, and humpbacks received that scientific name for their extraordinary long pectoral fins) keep flying around. The horizon is constantly broken by breaching, fluking, pectoral fin slapping whales. With the migratory peak in September, and given the population nearly doubled in size within the last decade, our interns and volunteers are lucky to enjoy this spectacular abundance with sometimes over 100 seen in a single day.

“The horizon is constantly broken by breaching, fluking, pectoral fin slapping whales. We sometimes see more than 100 humpback whales in one day.” – Ekaterina Kalashnikova, Marine Scientist and Operations & Commercial Manager at BCSS

Predominant behaviour events observed most recently (after breaching) included an inverted tail slapping, when the whale is belly up in the water, the fluke is lifted clear of the water and slapped, dorsal surface down, against the ocean’s surface; and a peduncle throw – the throwing of the entire fluke and peduncle out of the water in a lateral motion with no initial lifting from the water as in a tail slap, but just a single high scything motion, which is high energy behaviour and quite a spectacle to watch.

A peduncle throw is considered high energy behaviour. Photo by Ekaterina Kalashnikova. 

Photo identification to assess movement patterns, sub population structures and more

BCSS has received various international requests to provide logistic and scientific support regarding photo identification programs. We are currently working on ensuring the projects can proceed in 2023. Photo identification is a non-invasive method based on natural marks through photography when peculiar features are used for individual recognition without impact on the animal. Individual photo-identification of whales allows researchers to link sightings split by years and thousands of kilometers, providing opportunity for assessment of movement patterns and migration routes, sub population structure, site fidelity and residency time. For capturing the markings of the tail fluke’s photographs are taken from behind when the animal deep dives. Individual animals are identified by examining trailing edge, pigmentation patterns and other natural notches on the ventral side of flukes.

Two examples of identification photos. Photo identification is a non-invasive method which allows researchers to link sightings of individual humpback whales.  Photos by Ekaterina Kalashnikova. 

Join our Photo ID Program next season

Learn from researchers surveying humpback whales, who will be visiting BCSS next season. If you want to contribute to a better understanding of the migration patterns and regional connectivity, you can join these collaborative expeditions and be part of the Photo ID Program, assisting on-site specialists staying at BCSS. There is always a need for extra hands taking, sorting and uploading whale pictures – something that never gets boring.  For more information about participation in the program please contact us via info@bcssmz.org

About the researcher who wrote this article

Ekaterina Kalasnikova is a cetacean researcher who has been conducting annual observations in Tanzania for the last few years. She collects scientific data on dedicated boat surveys, employing visual and acoustic techniques with inclusion of photo-identification effort. While there is relatively more understanding in some areas of the West Indian Ocean, Tanzanian waters stand out with its significant knowledge gap on species distribution, movement range, population structure and their spatial-temporal preferences. The project aims to address this data paucity by building a national ID catalogue, which after comparison with existing regional datasets for connectivity evidence detection, may shed light on humpback whales’ ecology and habitat use while enhancing local research capacities. The research activities are possible due to collaboration and support of the Tanzania Marine Parks and Reserves Unit (MPRU), Mnazi Bay Ruvuma Estuary Marine Park (MBREMP), Zanzibar Institute of Marine Science and the Zanzibar Research Committee. Technical advice and support have been provided by the Marine Mammals Research Association (DMAD). 

Working at the Bazaruto Center for Scientific Studies, Ekaterina, together with the regional leading specialists, aims to build local capacity in Mozambique regarding photo ID methodology and other marine mammals research techniques.

Regionalisation of this study by embracing its Tanzanian and Mozambican components presents an opportunity for both countries to engage in broader regional cetacean research and monitoring projects, which will aid in better management and protection of the species.

For scientific questions please contact:
Ekaterina Kalashnikova, Bazaruto Center for Scientific Studies

Bazaruto Center for Scientific Studies
Host of the first permanent Ocean Observatory focused on multi-ecosystem time series research in Africa, the Bazaruto Center for Scientific Studies (BCSS) was established in 2017 as in independent, non-profit organisation with a mission to protect and support the fragile ecosystems of the Bazaruto Archipelago, Mozambique. The research station is located on Benguerra Island, off the coast of Mozambique.

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