The use of drones in wildlife observation has been a touchy subject for many researchers, but scientists with the Vancouver Aquarium believe they've found a way to use the technology to gather valuable data, without disturbing the fauna they're studying.

The aquarium's marine mammal research research program spent a second summer this year using a custom-made drone to take high-resolution photos of northern resident killer whales. The program's lead scientist says the images are invaluable, as they give a full picture of a whale's health, unlike photos taken from shore, or a boat.

"They can look pretty good from the side and still be quite thin," said Lance Barrett-Lennard, "We need that top view to really be able to tell what's going on."

A group of mammal-eating Bigg’s killer whales swim very close to shore off the coast of Northern Vancouver Island. Members of the T90s. T59s, T124A1 groups all came together during this encounter. (Vancouver Aquarium & NOAA)

The high-resolution images can detect changes in the whales' widths within a few centimetres, giving researchers a good idea of how much food they're getting. The images also allow researchers to detect pregnancies early on in the whales' 17-month gestation to help track miscarriages and young calves that don't survive.

For all that success, the use of drones to observe animal populations has seen its share of criticism. A study published this summer showed a 400% spike in the heart rates of bears when the unmanned aerial vehicles were nearby.

A custom-made, quiet drone

But the drone Barrett-Lennar and his team have been using was specifically designed to be quiet, and takes pictures from no lower than 30 metres above the surface of the water. He says it doesn't seem to be a disturbance.

In fact, the pilot project has been so successful, the team — which includes researchers with the U.S.'s Southwest Fisheries Science Centre — has expanded its study to look at the critically endangered southern resident killer whale population in the Strait of Juan de Fuca and the southern Georgia Strait.

"I'm not an advocate for the wholesale use of drones to fly over wildlife," says Barrett-Lennar. "But if you do it carefully with a very quiet drone it can be very, very useful."