Djibouti’s baby giants
The Gulf of Tadjoura holds a very special secret: an aggregation of the smallest whale sharks found anywhere in the world to date. Each year, David heads to Djibouti to learn more about these exceptional animals using photo identification and satellite tags.
David Rowat
Hello, I am the chairman of the Marine Conservation Society Seychelles and a member of the IUCN Shark Specialist Group. I moved to Seychelles with my wife Glynis in 1985 and through our diving activities we started to see ways in which we could help conserve local marine life. We began implementing several marine conservation and awareness projects, and one of the first of these was teaching children from the National Youth Service camp how to snorkel in the marine national park where the camp was situated. For many of the youngsters this was the first time they had ever...
Monitoring of juvenile whale sharks Rhincodon typus in the Gulf of Tadjoura, Djibouti
High intensity monitoring of an aggregation of very small juvenile whale sharks Rhincodon typus found in the Gulf of Tadjoura off Djibouti.
Very little is known about the demographics and behaviour patterns of whale sharks in this area. To better protect this important species, more data is needed.
This project enables the continuation of high intensity monitoring of this aggregation of very small juvenile whale sharks found in the Gulf of Tadjoura off Djibouti. This is an aggregation of very small juvenile whale sharks, significantly smaller than those found in most other coastal aggregations. As there is no aggregation of the ‘normal’-sized juveniles in this region, it may well be that these sub-juveniles move away from this area into other Indian Ocean aggregations as they mature. The capture of large numbers of individual photo-identities now will enable the confirmation of such movements during the coming years. The project covers a three-week intensive study period in January (the peak season) to capture the maximum number of photo identities as well as environmental data for the surrounding area. Ground-breaking work on measurement of growth rates using laser photo-grammetry began in 2010 and needs several years of data to develop robust measurements for a free-swimming population. This is the first such study globally. Photo-identities are added to the on-going database to enable population estimations; 95 identities were verified on the 2010 expedition and a further 53 in 2011, bringing the total number of sharks identified from this aggregation to 350. The results from 2010 have been presented at international meetings and in peer-reviewed publications.
To characterise the identities of individual whale sharks in the Djibouti aggregation to enable estimation of local population demographics, growth rates and abundance, and to inform regional populations estimates.
This will be accomplished through the following specific objectives:
- Capturing photo-identities, tissue samples, accurate size and supporting identification data from as many whale sharks in the Djibouti aggregation as possible.
- Digital matching of these identities to find unique individuals to populate the database.
- Making these identities available to other research groups working in the region to allow for future matching and comparison.