To effectively manage the impacts humans have on marine mammals, we need to know how many animals are in the management area (abundance), and how this number varies over time (trends), i.e. is the population going up, down, stable? One way to obtain this information is through sightings surveys, which estimate whale or seal abundance in specific areas. Different methodologies allow carrying out surveys for seals and whales from planes, boats or land.
The video below is an animation created by the Greenland Institute for Natural Resources to illustrate the method the scientists use to estimate the population size of cetaceans off Greenland.