Long-term membership of whale sharks (Rhincodon typus) in coastal aggregations in Seychelles and Djibouti
![paper](http://sharkyear.com/wp-content/uploads/2011/06/paper.jpg)
David Rowat, Katie Brooks, Abi March, Ciara McCarten, Daniel Jouannet, Luke Riley, Gareth Jeffreys, Morgan Perri, Michel Vely and Bruno Pardigon.
ABSTRACT:
In coastal waters of several locations globally, whale sharks (Rhincodon typus) form seasonal aggregations, most of which largely comprise juvenile males of 4–8 m length. Evaluation of the period that individuals stay within these size- and age-specific groupings will clarify our understanding of the transition between life-stages in this species and how this might affect their long-term conservation. Long-term photo-identification studies in Seychelles and Djibouti provided data to evaluate this. The Seychelles aggregation had 443 individuals averaging 5.8 m identified between 2001 and 2009; however, the Djibouti aggregation comprised smaller individuals of 3.7 m mean length with 297 individuals identified between 2003 and 2010. In Seychelles, 27% of individuals identified in 2001 were seen again in 2009, while in Djibouti none of the whale sharks identified in 2003 were seen in 2010, although 13% from 2004 were. This suggests that membership periods in the Djibouti aggregation are shorter than in the other juvenile aggregations, such as in Seychelles. Continued photo-identification monitoring of other Indian Ocean aggregations might in time show the next location of these young sharks’ life-cycle and thereby allow development of informed national and regional management plans.
Marine and Freshwater Research 62(6) 621-627 http://dx.doi.org/10.1071/MF10135