Scientists from the National Oceanic and Atmospheric Association, in conjunction with researchers from the Vancouver Aquarium, have begun filming wild orca populations in order to better study the elusive killer whales.

Using a robotic aerial drone that flies a mere 100 feet above the animals, the team has started to monitor a specific breed of orca- the Northern Resident killer whales, which are an endangered species under Canada’s Species at Risk Act. The whales are filmed as they swim through the Johnstone Strait in British Columbia.

Northern Resident killer whales primarily eat Chinook salmon, which are also considered an endangered species. To study the effect of a decreased salmon population on orcas, a specially built hexacopter was designed and launched by the team.

While wild orcas have been filmed many times from helicopters, the choppers need to fly far above the water’s surface in order not to disturb the whales. However, the team’s hexacopter flies quietly above the ocean at a distance of 100 feet, close enough to get highly detailed pictures without spooking the animals.

The hexacopter has currently taken pictures of 82 whales, which allows scientists to determine specific population demographics. Researchers can analyze how fat or skinny whales are to detect whether the declining Chinook salmon has an effect on their eating habits. They can also tell how many whales are pregnant and how many of these pregnancies bear live offspring.

A healthy Northern Resident orca female usually weighs around 16,500 pounds, while males can reach an astonishing 22,000 pounds. Using the hexacopter’s high-resolution photos, scientists are able to determine the weight of the whales in order to monitor whether the population is healthy.

The pictures also help scientists monitor the overall whale population and mortality rate. According to biologist John Durban of NOAA’s Southwest Fisheries Science Center, hexacopter monitoring “can give us a more sensitive measure that we might be able to respond to before whales die. Mortality is a pretty coarse measure of how well the population is doing because the problem, if there is one, has already occurred.”