Scientists Discover How to Measure Weight of Live Whales Using Drones

A southern right whale female rolling on her side, and exposing her lateral side to the surface while gently touching her calf. (Photo: Fredrik Christiansen)

(CN) – While drones are used for a number of civilian and military applications, biologists on Wednesday announced they found another use: measuring the weight of live whales.

The new method could signal a breakthrough in data research for scientists as they previously could only measure body mass and volume of dead whales due to their immense size and aquatic life, according to the study published in the journal Methods in Ecology and Evolution.

“Knowing the body mass of free-living whales opens up new avenues of research. We will now be able to look at the growth of known aged individuals to calculate their body mass increase over time and the energy requirements for growth. We will also be able to look at the daily energy requirements of whales and calculate how much prey they need to consume.” said Fredrik Christiansen, assistant professor at the Aarhus Institute of Advanced Studies in Denmark and lead author of the study.

The scientists said the process is already being used in monitoring the impacts that kelp gull harassment may have on the health of southern right whale calves.

“The use of drones to estimate whale weight and condition, as well as to individually track calves while they grow beside their mothers, has been a real breakthrough in our investigation,” the study scientists said in a statement. “In the past we’ve had to rely entirely upon stranded carcasses which added all sorts of uncertainties to our studies.”

Using high-quality photos of 86 whales off the coast of Península Valdés, Argentina, the scientists were able to calculate length, width and height measurements which were then used to calculate body mass.

“We used this model to estimate the body volume of whales caught in scientific whaling operations, for which body girth and mass was known. From these estimates of body volume, we could then calculate the density of the whales, which we in turn could use to estimate the mass of free-living whales photographed by our drones.” Christiansen said.

The researchers have collaborated with the Digital Life Project at the University of Massachusetts to create full-color 3D models of the whales for use in both research and education. The use of such models could extend to even larger species, such as baleen whales. Research on “their size has historically been limited to dead specimens, with most samples coming from whaling operations, accidental fisheries bycatch or beach strandings,” the study authors said.

“The difficulty in measuring body mass reliably in free-living whales, has prevented the inclusion of body mass in many studies in ecology, physiology and bioenergetics. This novel approach will now make it possible to finally include this central variable into future studies of free-living whales,” Christiansen said.

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