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#WhereAre the Whales_2023 ? A regional synchronised whale-counting day

In September 2024, a synchronised Humpback Whale Counting day was organized among organisations at different locations in the south-western Indian Ocean, contributing to an existing initiative lead by Matt Richmond in East Africa. The general objective of the synchronized day is to generate a standardised indicator of humpback whale occurrence at different locations in order to assess regional variations, inter-annual fluctuations and long-term trends. 

The counts were conducted over a 4-day period, from the 14th to the 18th September at 9 locations in 5 countries: 
– In South-Africa: with MRI Whale Unit (Els Vermeulen), Nelson Mandela University (Gwen Penry) 
– In Mauritius- Marine Megafauna Conservation Organisation Mauritius with Lana Barteneva
– In Madagascar: by Cetamada (Erwan Bailby) and Megaptera (Michel Vely)
– In Mozambique with All Out Africa (Jennifer Keeping), MAR-Expedition (Nakia Cullain) and Dolphin Encountours Research Center (Angie Gullan). 
– In Reunion with Globice (Violaine Dulau, Jean-Marc Gancille)

Survey effort varied between sites, from 3 hours to the full day, with various sea conditions recorded. The highest numbers were reported in Reunion (Cap Homard), where over 30 ind. per hour were recorded for most of the day, and > 50 ind./hr in the morning,  when sea conditions were excellent. Lower numbers were recorded at other sites. On the eastern coast of Africa, low sighting rates were considered associated with difficult sighting conditions. 

At some locations (Reunion, Madagascar, Mauritius), this was a first experience of attempting surveys from shore, while regular shore-based surveys are organized by some other organisations in East Africa (Mozambique, South-Africa). Partners were motivated to continue this effort in future years. A meeting will be planned to refine a common survey protocol (duration, numbers of days in the season, etc…) for the 2024 humpback whale season. 

Contributors : Anais Charbonnel, Violaine Dulau