Study of humpback whale populations in the southwest Indian Ocean from Very High Resolution satellite images

The appeal of using VHR satellite imagery to conduct biodiversity studies particularly in large, remote and inaccessible ocean surfaces where traditional survey methods are limited or impractical, had already been raised by various scientific communities, including the IWC.

The southwestern Indian Ocean basin is a true sanctuary for large whales. Considering the global context of climate change, past and new threats, this area reveals the urgency of addressing significant gaps in the integrated understanding of spatial ecology of protected cetaceans’ species (population abundance, spatial distribution and migration trajectories, inter-annual variability factors), and the characterization of human pressures (legal and illegal) at sea,  

The THETYS project consisted of an unprecedented proof of concept on the scale of the South-West Indian Ocean, aiming to assess the potential for detecting humpback whales and their environmental conditions using Very High Resolution satellite images.

The project aimed at real innovation in the reliability of the method, by combining remote sensing engineering and marine field ecology in a synchronized way (1) to ensure unequivocal identification of species, (2) to confirm the visual annotations that will be made from the images, and (3) to promote “indigenous knowledge” with local scientific teams and/or NGOs. In addition, satellite programming is a non-intrusive and flexible method for conservation and decision making.

In 2021, with the support of the NGO Abyss and the producers of spatial data the possibility of detecting humpback whales from VHR satellite images by negotiated programming has been confirmed.

The pilot sites selected for this study are : the south African coasts, Madagascar and La Reunion.

For this presentation, we will showcase a sample of the best resolutions on the global satellite imagery scene; and the first step of how to "label" these images by visual detection of the target species and human activities, and by organizing ground truth campaigns synchronized with satellite taskings.