Counting whales from space

Abstract

Using Very High Resolution satellite imagery, alongside image processing software, BAS scientists were able to automatically detect and count for the first time southern right whales breeding in part of the Golfo Nuevo, Peninsula Valdes in Argentina. Whale populations have always been difficult to assess because traditional methods are localized, expensive and lack accuracy. The ability to count whales automatically over large areas in a cost effective way will be of great benefit to conservation efforts for this and potentially other whale species and populations, some of which are endangered. Previously, satellites provided limited success, but their accuracy has improved in recent years. In this study whales were first manually identified and counted in a single WorldView2 satellite image, several automated methods were then compared with this manual method. The best results were obtained with a ‘thresholding’ of the Coastal Band of the WorldView2 image, which uses light from the far blue end of the spectrum to penetrate the water column deeper and allows us to see more whales. This technique found 89% of the probable whales identified in the manual count. Future satellite platforms will provide even high quality imagery and Worldview3 is planned to be launched this year. This will allow for greater confidence in identifying whales and differentiating mother and calf pairs. Such technological advances may also allow scientists to apply this method to other whale species.