Dolphins can often be identified by the nicks and notches in their dorsal fins. These are caused by rough play, shark attacks and even damage from boat propellers.
GMR researchers have estimated approximately 250 dolphins frequent the Cape Naturaliste area. About 25% of these have identifying damage to their dorsal fins. They have been photographed over about 8 years so far and this provides a long term record that can be used in Mark-Recapture analysis and in the long-terms to assess the viability of the population. We already know that some of these dolphins (with easily identifiable damage) are residents, having stayed in the area over the entire 8 year period and still accompany the dolphins they were with when they were originally photographed!
These photographs are still to be processed. As computer based matching techniques evolve, GMR will increasingly look to using these to process such images. In the meantime, the photo-ID research continues.
The dolphins spend can spend significant time surfing. They catch a wave and ride it into the beach. At the last moment they can turn and leap out of the back of the wave, sometimes 3-4 meters into the air. When the conditions are right, they can continue this for hours.