2017 Season: Results

February 27, 2018

Since 2015, the Madagascar Whale Shark Project has been collecting data on whale sharks in Nosy Be. The aim being to understand the ecology, behaviour and conservation issues that whale sharks face in the Nosy Be area.

Here are our key numbers for the 2017 season:

-93 survey days

-1113 bait balls of mackerel tuna/bonito recorded with 40.7% whale shark presence

-342 photo-identified encounters with whale sharks

-105 individuals, 20 females and 85 males.

-33 of these sharks were already present in our database like Michel, Ernest, Théodore, Ignace…

-72 newly-identified sharks like Sirius, Elina, Brigitte, Tristan, Willy…

-5.2m TL is the mean size

– 20 encounters with Michel

-240 sharks identified since 2015!

Stella swimming alongside Franck (MD-224) (c) Simon Pierce

An epic season! In conclusion, whale sharks seem to use the same area of the bay through the local whale shark season (September to December) across years, building on the results of our 2016/17 satellite-tagging study (Diamant et al. In review). Still none of the 240 immature Nosy Be sharks have been identified from surrounding countries (based on the global database at www.whaleshark.org), suggesting a lack of regular connectivity between the sharks at Nosy Be and other known coastal aggregations in the WIO, such as in the Seychelles, Mozambique and Tanzania. This also indicates that the sharks may be transient to the Nosy Be area, and are only visiting at certain times of their lives, possibly to stock up on nutritious food before heading out into the open ocean once they reach bigger sizes.

A big thank you to everyone who contributed to this year’s data collection:

Arthur et Tanguy Guillemain d’Echon, Elina Sourisseau, Juliet Cussaguet, Mathieu Le Peru, Thomas Quehen, Vincent Quiquempois, Joshua Rambahiniarison, Kelly Morvan, Carole Perrin, Stéphanie Floirat, Arnault de Peretti, Mylène Richard, Guillaume Bonnaud, Michaël Coconi, Salvatore Cerchio, Fanja Andrianarisoa, David Robinson, Simone Caprodossi, Olivier Collinet, Barbara Bini, Jacques Vieira, David Goy, Benoît Raoul, Juliet Cussaguet, Mathieu Le Peru, Cédric Penti, JB Galvès, Corinne Robert, Maxime Brogniart, Norman Guichard, Simon Miller.

All data, photos and figures are the exclusive property of the Madagascar Whale Shark Project, unless stated otherwise, and are not to be copied or reproduced in any manner without authorization from the authors.