In the early 1970’s Canadian researcher Dr. Michael Bigg and his colleagues developed a technique that revolutionized the study of killer whales. They discovered that every individual killer whale had unique markings and could be readily distinguished in high quality photographs. They compiled catalogues of photo-identified killer whales, and used them to identify social clusters, populations and movement patterns. Over time, they were also able to use them to estimate birth and death rates and to determine social systems. Photo-identification remains the single most important tool for systematic research on killer whales.
Dorsal fin: the erect fin on the back of a whale
Saddle patch: the lighter pigmented area directly posterior to the dorsal fin on the back of a killer whale
Researchers Dr. John Ford, Graeme Ellis, and Jared Towers of Fisheries and Oceans Canada, Dr. Lance Barrett-Lennard and his team at the Vancouver Aquarium, and Ken Balcomb and his team at the Center for Whale Research use photo-identification every time they encounter killer whales in the wild. The method is key to the long-term monitoring of killer whale populations in BC, which is now one of the world’s longest and most comprehensive studies of any animal species. Photo-identification has made it possible for the researchers to accurately determine year-by-year trends in killer whale productivity and survivorship in the face of human-induced environmental changes.
Photo: Graeme Ellis
Dr. Michael Bigg looking at ID photos of killer whales.
- Researchers use a high-quality black and white photograph, typically of the left side of the whale.
- A killer whale's right and left saddle patches are often quite different.
- Researchers arbitrarily chose to photograph the left side of the whale to simplify and standardize the system.
Photo: Lance Barrett-Lennard