How do you accurately weigh a living whale? It's probably not a question that's troubled you at all, but it has left scientists scratching their heads in puzzlement over the years.
Well now, they are mystified no more because researchers from Denmark have solved the conundrum thanks to aerial photographs taken by drones.
Through their model researchers were able to accurately calculate the body volume and mass of wild southern right whales. They flew drones over the large mammals as they were swimming in clear water in their winter breeding grounds off the coast of Argentina.
Taking Clear Images
Images were taken when adults and calves came to the surface to breathe. From these snaps, scientists obtained the length, width and height measurement of 86 individuals. These were combined with historical catch records to estimate body mass.
Body mass is a key factor in the success of whales as a group, determining such factors as growth rates, food requirements and energy uses. Until now, there was no way to estimate the body mass of free‐living whales.
The work was carried out by the Aarhus Institute of Advanced Studies in Denmark in collaboration with the Southern Right Whale Health Monitoring Program in Argentina and the Woods Hole Oceanographic Institution in the United States.
Research Details Available Online
An outline of the project (Estimating body mass of free‐living whales using aerial photogrammetry and 3D volumetric) appears in the British Ecological Society journal Methods in Ecology and Evolution (MEE).
It is expected that this approach could be modified to estimate the mass of other free-living marine mammals.