Osa Conservation Supports Research in Golfo Dulce: Photo-identification of Bottlenose dolphins

Dolphin B43 shown alongside a rendered outline of its dorsal fin. We saw this individual five times.

An unexpected but delightful result of our survey work in Golfo Dulce was the identification of about 80 individual Bottlenose dolphins (Turciops truncatus), some of which can be seen in the Appendix of my 2010 report.

How does one go about identifying dolphins? Well, pioneering biologists studying various species discovered ingenious ways to distinguish individuals. Jaguars have unique spots. Gorillas have unique nose prints. Dolphins have unique dorsal fins. By examining the shape, natural markings, scars and trailing edge, a dorsal may appear as distinct as a fingerprint. Of course dolphins don’t sit quietly at the surface while you study the intricacies of their dorsal patterns, so ID work is best done through photos. Luckily, we managed to get photographs for almost 90 percent of our dolphin sightings.

A good close-up photo allows us to visualize, even trace, the dorsal outline. Once we “know” a dolphin, we can often recognize it from a distance. Then we can go back and look for it in other sighting photos and thus begin tracking its movements, as well as associations with fellow dolphins. It’s a tedious task, yet also exciting. Suddenly a sea of dorsal fins becomes an intriguing puzzle of “who’s who”.

Photo-ID catalogs and databases are created to expand scientific understanding of dolphin populations and their habitats. But good science is only part of it. I also hope our photo-ID images will serve as outreach material. Familiarity breeds a sense of responsibility — we are more likely to help those we know — so by introducing the Osa community to their dolphin neighbors, people may be even more inspired to protect them.

Brooke Bessesen conducted Marine research at the Osa in 2010 and 2011 as a recipient of the Greg Gund Memorial Fellowship. Check out her Golfo Dulce report on our website.

Golfo Dulce report

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