Aerial surveying

How many whales are there?

Counting whales is no easy task! To do so, scientists conduct aerial surveys. From high in the air, whales are clearly visible when they surface to breath. They only remain there for a very brief moment, however, as they spend between 40 and 80% of their lives below the surface.

  • Observing St. Lawrence belugas from the air
  • © GREMM

Whale-counting method:

  • A portion of a whale-inhabited sector is flown over while following a specific itinerary (systematic or random, depending on the method selected), preferably on a calm day with excellent visibility.
  • Such surveys may consist of visual surveys, photo surveys, or a combination of the two. During visual surveys, the presence of whales is noted by observers. In photo surveys a camera takes pictures at regular intervals. Back at the lab, the whales visible in the photos are counted.
  • To reach an estimate, the number of whales counted in the photos must first be adjusted to account for sectors not covered.
  • Subsequently, a correction must be made to take into consideration animals that were below the surface and thus invisible to the camera and to observers when the plane was passing overhead.

Last update: May 2017