Photo Identification

Photo-identification is a well-established tool in wildlife monitoring, both in terrestrial and marine ecosystems. It uses natural markings to identify and follow individuals of a wide variety of animal species, e.g. tigers, manatees, dolphins, whales and even octopuses.

A number of shark species have been studied worldwide applying this non-invasive technique, including spotted raggedtooth or sandtiger sharks (Carcharias taurus), whale sharks (Rhincodon typus), whitetip reef sharks (Triaenodon obesus) and great white sharks (Carcharodon carcharias).

The ability to follow individuals over time provides valuable insights into the sharks' movements, site fidelity, habitat use, behaviour, intra- and inter-specific associations, and reproductive parameters.

In the Red Sea, the number of divers present all year round and the affordability and resulting widespread use of digital underwater cameras make photo-identification a valuable tool for elasmobranch (shark & ray) research. The collection of shark and ray photographs from both dive guides and tourists is the main objective of this study (see sidebar for details).

A minimum of 5 Red Sea species have natural markings suitable for this method:

• oceanic whitetip shark (Carcharhinus longimanus, see http://www.longimanus.info)
• whale shark (Rhincodon typus, see http://www.whaleshark.org)
• whitetip reef shark (Triaenodon obesus, see http://www.whitetip.org)
• manta ray (Manta birostris, see http://marinemegafauna.org)
• grey reef shark (C. amblyrhynchos)

Examples of natural markings of different elasmobranch species (from left to right): spot pattern of whale shark (Rhincodon typus), dorsal fin of grey reef shark (Carcharhinus amblyrhynchos), tail of silky shark (C. falciformis), spot pattern of whitetip reef shark (Triaenodon obesus), dorsal fin of oceanic whitetip shark (C. longimanus), and spot pattern of manta ray (Manta birostris). © Elke Bojanowski, except: © Dray van Beeck for image 1].

For one of these species, the oceanic whitetip shark (Carcharhinus longimanus), an extensive catalogue comprised of more than 500 individuals from the Red Sea is already available. It was compiled over the last 6 years with the help of around 520 contributors and continues to grow with more images being submitted (read more...).

Exploratory attempts to create similar catalogues for grey reef sharks (C. amblyrhynchos, read more...) and silky sharks (C. falciformis, read more...) were promising, and even the spot pattern of individual Zebra Sharks (Stegostoma fasciatum), although known to change with age, might provide sufficiently reliable information to apply photo-identification methods.

While initial efforts will be focussing on the large pelagic elasmobranch species, this HEPCA research project will provide the platform to collect and store any kind of photographic material related to Red Sea elasmobranchs for scientific and conservation purposes.