A groundbreaking new study documenting the first multiple visual and acoustic records of melon-headed whales (Peponocephala electra) in southern Tanzania has been published in the May 15 issue of Aquatic Mammals Journal. The research, conducted by Ekaterina Kalashnikova of BCSS, and colleagues, supervised by Dr Aylin Akkaya of DMAD, provides significant new insights into the distribution and interspecific associations of this rarely documented species in the region.
Melon-headed whales. (E.Kalashnikova/A.Akkaya/P.Lyne)
During dedicated humpback whale (Megaptera novaeangliae) research in Tanzania’s Mtwara region between 2021 and 2024, five separate sightings of melon-headed whales were recorded, alongside the first documented acoustic recordings of the species in Tanzanian waters. Notably, this study marks only the third reported sighting of the species within the country’s territorial waters and the first confirmed interactions with Risso’s dolphins (Grampus griseus).
Sine showing two inflexions frequently displayed in whistles of melon-headed whale recordings (E.Kalashnikova/A.Akkaya/P.Lyne)
“Understanding the presence and habitat use of melon-headed whales in East Africa is crucial, as dedicated cetacean research in continental coastal waters has been limited,” said lead author Kalashnikova, who heads the Tanzania Cetacean Program and is a part of the Bazaruto Center for Scientific Studies team in Mozambique. Dr Akkaya, who has been instrumental in setting the study off the ground, adds: “Our findings contribute to baseline knowledge that can inform conservation strategies in a region increasingly affected by offshore industrial activity.”
Humbpack whale and Melon-headed whale. (E.Kalashnikova/A.Akkaya/P.Lyne)
The study highlights that melon-headed whales, typically found in offshore pelagic waters, were observed in depths ranging from 500 to 700 meters near the Mnazi Bay Ruvuma Estuary Marine Park (MBREMP). The species demonstrated close associations with humpback whales and Fraser’s dolphins (Lagenodelphis hosei), as well as not documented to date interaction with Risso’s dolphins.
Melon-headed whales. (E.Kalashnikova/A.Akkaya/P.Lyne)
Additionally, acoustic recordings from the study reveal a diverse vocal repertoire, including echolocation clicks, burst-pulsed sounds, and whistles, with variations similar to populations studied in the Pacific and Caribbean. The findings underline the need for continued bioacoustic research in the region to further understand melon-headed whale ecology and their vulnerability to increasing anthropogenic pressures, such as offshore oil and gas exploration.
The records of melon-headed whale sightings and strandings (both dead and alive) as well as known occurrences in the Southwest Indian Ocean. (E.Kalashnikova/A.Akkaya/P.Lyne)
“The documentation of this species in Tanzania underscores the importance of systematic marine mammal surveys in data-deficient regions,” added Patrick Lyne who co-authored the paper and lead acoustic analysis. Authors agree that “the presence of melon-headed whales may be more common than previously thought, and further research is necessary to determine whether they form coastal units similar to populations observed in other parts of the world.”
Variation on the contour shape by the type of the tonal sounds. (E.Kalashnikova/A.Akkaya/P.Lyne)
Melon-headed whales and humpback whale. (E.Kalashnikova/A.Akkaya/P.Lyne)
The study, Recent Visual and Acoustic Records of Melon-Headed Whales (Peponocephala electra) and Interspecific Associations in Tanzania and a Review of Regional Records in the Southwest Indian Ocean, is co-authored by Dr Aylin Akkaya (DMAD-Marine Mammals Research Association, Turkey), Davis G. Orio (Mnazi Bay Ruvuma Estuary Marine Park, Tanzania), and Patrick Lyne (DMAD-Marine Mammals Research Association, Turkey), has been published in Aquatic Mammals Journal, Volume 51, Issue 3, on the 15th of May 2025.
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Ekaterina Kalashnikova, Bazaruto Archipelago – Ocean Observatory Bazaruto Center for Scientific Studies ekaterina.kalashnikova@bcssmz.org
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