Findings from a study conducted by Ekaterina Kalashnikova of the Tanzania Cetacean Program and BCSS, Davis Godfrey Orio of the Mnazi Bay Ruvuma Estuary Marine Park (MPRU), and Dr. Aylin Akkaya of the DMAD-Marine Mammals Research Association, present the first recorded instance of humpback whales feeding in their East African breeding grounds. The research has just been published in Ethology Ecology & Evolution.
Humpback whale (Ekaterina Kalashnikova/BCSS)
Humpback whales typically adhere to a well-documented migratory pattern, breeding in warm tropical waters and feeding in nutrient-rich high-latitude regions. However, emerging research suggests that these whales may engage in supplementary feeding outside their main foraging zones. While this behavior has been recorded in other breeding stocks across the Southern Hemisphere, the recent findings mark the first scientifically documented case within the waters of Tanzania.
During dedicated boat-based surveys in August 2023 and August 2024 in the Mnazi Bay Ruvuma Estuary Marine Park, researchers observed humpback whales exhibiting characteristic lunge-feeding behavior. At least two individuals were seen performing vertical and lateral lunge feeding, a highly energy-intensive strategy used by filter-feeding cetaceans to engulf large volumes of prey-laden water. The presence of other species sharing the same prey with humpback whales —including several species of toothed whales, schools of tuna, and aggregations of seabirds—further corroborates the likelihood of active feeding.
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Humbback whales (Ekaterina Kalashnikova/BCSS)
These findings underscore the oceanographic productivity of the Mnazi Bay seascape, and potentially other similar areas in the larger Western Indian Ocean. The presence of feeding whales highlights the role of these marine giants as ecosystem engineers, contributing to nutrient cycling and overall biodiversity. Additionally, this  behavioral flexibility may reflect an adaptive response to environmental changes and fluctuations in prey availability, both of which are crucial for recovering humpback whale populations in the WIO.
While these observations provide an important baseline, further research is necessary to fully understand the drivers and frequency of supplementary feeding in WIO waters. Expanding survey efforts, incorporating acoustic monitoring for feeding calls detections, and analyzing prey abundance will help clarify the extent of this phenomenon and its ecological implications.
Humpback whales (Ekaterina Kalashnikova/BCSS)
BCSS, located along the humpback whales’ migratory corridor in the Bazaruto Archipelago, remains a vital research hub for studying marine megafauna. Through its Scientific Training Program, BCSS offers hands-on experience in marine fieldwork, scientific diving, and ecological surveys, equipping students and researchers with the skills necessary to advance the study of cetaceans in the region.
We invite collaboration from researchers, conservationists, and institutions to further explore the role of East African waters in ecology of migrating humpback whales. Protecting and studying this dynamic marine ecosystem is essential—not just for the whales themselves, but for the health of the broader oceanic environment and the coastal communities that depend on it.
Reference: Kalashnikova, E., Orio, D. G., & Akkaya, A. (2025). First documented observation of feeding behaviour of humpback whales (Megaptera novaeangliae) in its breeding range off the southern coast of Tanzania. Ethology Ecology & Evolution, 1–7. https://doi.org/10.1080/03949370.2024.2437353
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Ekaterina Kalashnikova, Bazaruto Archipelago – Ocean Observatory Bazaruto Center for Scientific Studies ekaterina.kalashnikova@bcssmz.org Â
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