GOMBESSA II: an expedition to discover the secrets of a South Pacific atoll’s pass

Between June and July, we conducted a 40 days expedition at the South pass of Fakarava called Tetamanu, a remote location of the Tuamotus (French Polynesia) to study the hidden secret lives of sharks and groupers and live along the daily cycle of the ocean.

This expedition was funded by BlancPain and organised by Laurent Ballesta from Andromède Oceanologie. CRIOBE was in charge of scientific procedures. Parallel to this scientific expedition, a 90′ Documentary was produced for ARTE (will be lauched on TV in early 2015).

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SCIENCE:

First, we mapped the pass using a multi-beam sonar system that allowed to get a 3D view of the pass and geolocalised important aspects of the pass (shark and grouper aggregations and all equipments deployed in the pass).

Then we set VR2 acoustic receivers and tagged groupers and sharks in order to better understand their spatial use of the pass. We then deployed 15 underwater thermographs in order to track fine-scale variability of temperature due to currents.

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Camouflage groupers happen to form huge aggregations within the pass at this time of the year in order to spawn at full moon of June and July. We therefore studied every single behaviour of fish related to spawning or territorial activity.

loche mabree - merou - camouflage grouper - Epinephelus polyphekadion - vincent truchet - 4loche mabree - merou - camouflage grouper - Epinephelus polyphekadion - vincent truchet - 3

(Photo Credit: Vincent Truchet  http://www.vincent-truchet.com/)

We then studied the grey reef shark school that forms in the middle of the pass composed of a huge number of individuals (about 700). Night dives were also conducted to study shark activity and hunting patterns at night.

banc de requin gris - school of grey reef shark - mur de requin - wall of shark - vincent truchet(Photo Credit: Vincent Truchet  http://www.vincent-truchet.com/)

More information on the science arround this project will come soon.

DOCUMENTARY:

A documentary for ARTE was produced by Gil KEBAILI (Les films d’Ici). This documentary deals with the daily cycle of the life in the pass, following also the activity around the spawning aggregation.

It will be available on TV in early 2015 as a 90′ film in ARTE. arte

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10354231_10152313852172986_3822337056370847456_nJohann et Laurent_Fakarava 2014

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