Photo-identification

Much of what we have learned about the lives of North Atlantic killer whales is based on a technique called photo-identification. The initial discovery by Dr Michael Bigg (in 1972) that individual killer whales can be recognised from photographs made it possible to start following the lives and behaviour of individually known killer whales, which revolutionised the research conducted on killer whales.

Photographs taken of the dorsal fin and the grey saddle patch behind the fin can be used in identifying individuals. The pigmentation, shape and scar pattern on these areas are unique for each whale. Scars in the saddle patch behind the dorsal fin show as clear permanent white or black marks. Some of the whales also have saddle patches with a unique, easily recognizable shape. Equally, nicks, cuts or tears that a killer whale gets in its dorsal fin, leave a permanent mark on the fin.

Some of the whales are easily recognisable, even at sea, due to the large tears and nicks on their dorsal fin. Others bear markings that can only be recognised from a close look at the photographs taken of them.

By photographing killer whales we are able to e.g. estimate the size of the population, determine seasonal distribution patterns, social organisation and even individual and group specific traits.

Photo-identification catalogues of identifiable individuals exist for Norwegian, Icelandic and Scottish killer whales. Today we have approximately 600 identified individuals in the Norwegian ID-catalogue, 400 in the Icelandic ID-catalogue and 100 in the Scottish ID-catalogue.

9140 Icelandic killer whale 9140 photographed in 1991 on the east coast of Iceland. (Click on image to make larger).	9140 9140 in 2001 on the southwest coast of Iceland. She is still recognisable as the same individual from the scars on her saddle and very small nick at the tip of her fin. (Click on image to make larger)