Whale Sharks, Djibouti
Gulf of Tadjoura, Djibouti
Key Objective:
The continuation of high intensity monitoring of this aggregation of very small juvenile whale sharks (Rhincodon typus) found in the Gulf of Tadjoura off Djibouti.
Why this is important:
Very little is known about the about the demographics and behaviour patterns of whale sharks in this area. In order to better protect this important species more data is needed about them.
Background
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, partly funded by SOSF in 2010-2011. Globally this is an aggregation of very small juvenile whale shark, 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 over 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 on the surrounding area. Ground breaking work on measurement of growth rates using laser photo-grammetry was started in 2010 and needs several years of data to develop robust measurements of growth rates on a free swimming population, the first such study globally.
Photo-identities are added to the on-going database to enable population estimations; 95 identities were verified in the 2010 expedition and a further 53 in 2011, bringing the total number of sharks identified from this aggregation to 350. SOSF still and H.D. video photography was captured in 2009 and the results from 2010 have been presented at international meetings and in peer reviewed publications.
Aims and Objectives
To characterise the identities of the individuals in the Djibouti whale shark 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:
- Capture photo identities, tissue samples, accurate size and supporting identification data from as many whale sharks in the Djibouti aggregation as possible
- Digitally match these to identify unique individuals to populate the database
- Make these identities available to other research groups working in the region to allow for future matching and comparison
Project leader:
David Rowat
Partners:
MEGAPTERA, DECAN
Related threat:
Years funded:
2010-2011
Two weeks with lots of sharks!
— .(JavaScript must be enabled to view this email address), 22 January, 2012
Once again a similar pattern of shark occurrence was found in week two of the expedition to that in the first; shark numbers started off okay with over twenty encounters for each boat on the first session, but then numbers…
Welcome to Djibouti!
— .(JavaScript must be enabled to view this email address), 06 January, 2012
Well Djibouti 2012 is officially underway with the first of the three week expeditions arriving back in port as we post this report. The first week was one of great contrasts with the week starting off really well with four…
Djibouti a fascinating area
— .(JavaScript must be enabled to view this email address), 14 July, 2011
Djibouti is a tiny country at the top right-hand corner of Africa… it is an incredibly interesting country as it straddles the intersection of two of the great continental plates that progress down Africa through Djibouti, Ethopia and Kenya as…