Why do turtles return to their birthplace to lay ? episode 2

Les tortues aux Glorieuses

Place: The Glorious and the Geyser's Bench

Conducted in 2009

Expedition Leader : Simon BENHAMOU CNRS Montpellier

And yes, here we go for a new mission. One would think that at the end of the fourth one is blasé, one is bored. But a mission in Les Eparses is an eternal adventure, a new human experience, a new challenge. We leave the eyes full of dreams, we come back the skin full of salt, burnished with a merciless sun, and eyes full of hope for the future of the planet, a healthy planet, pure, simple and beautiful where we men could live in harmony and in respect of a welcoming and abundant nature.

A mission on Antsiva, it is also and above all a new human adventure, a place of exchange, of listening, without prejudices, a place of sympathy, of jokes, of emotions, of admiration ... like this tiger shark of 4 meters evolving peacefully between the two appendices, or this dance of the turtles in reproduction in the turquoise water, at the foot of the schooner, hard reality of a reproduction where the battle of the males for the female is done with rage, but probably passion too ...
Then a mission in scattered Antsiva, it is simply an enchantment, an excessive dream that is transformed into reality, communion of nature and man who reveals without deviation our nature. How to be jaded faced with this existing reality? So stay humble in the face of these experiences, and enjoy every moment as if it were the last.

... and the scientist

Before embarking, a sentence was trotting in my head, especially as a head of mission: "Extremely dense mission Glorious 2009, will have to manage ...". And that's what we've done.
First on the green turtles in reproduction, the species Chelonia mydas. The aim of this first part is to understand how marine turtles manage to find their birthplace - a bit like salmon - to deposit eggs, the only ones guaranteeing the survival of the species. Magnetic fields, smell? No answer for the moment. To unravel the mystery, we captured 12 turtles on the beach during the laying phase and on which we put Argos tags to follow their journeys on the high seas; some with magnets, others not, the aim being to see if the magnetic fields blur their sense of orientation when moved at sea. The first results seem to indicate that no ... it will be necessary to inject the data in powerful software to confirm these first results.

Then, on the immature tortoises, which find in Glorious waters, a perfect habitat of development. The goal of this mission was to capture 50 immature green turtles, tag them, weigh them, and photograph them.
The advantage of such an approach is to be able to study their rate of attendance, their residence and growth time. Do they stay 1 year, 5 years on these sites? Do they grow to 1 cm per year? From 10? These are all questions that are fundamental for putting in place effective management plans to protect these species in danger. We were able to capture 42 green turtles, and highlighted that the growth rate was of the order of 1.5cm per year and that some had been there since 2005 ... 4 years.

Finally, the last part was about the fish: are there links between some species found Glorious and these same species in Mayotte? In the meeting ?
To do this, the goal was to capture 50 fish from 3 different species for genetic samples. The genetic tool is a powerful tool for understanding the links that can exist between populations. In this context, it will enable us to understand to what extent the marine protected areas of the South West Indian Ocean are linked - or not, to each other.
This type of response will allow us to highlight whether the current structure of the network of marine areas of the South West Indian Ocean is well constituted or whether it is necessary to create new ones to refine the mesh and optimize protection. marine resources.

Nouvelle mission à bord d’Antsiva. Certains commencent à connaitre le bateau par cœur. D’autres sont pour la première fois les bienvenus à bord. Comme d’habitude, l’équipe des turttle-men se précipitent sur la cabine avant mais une mauvaise surprise les attend : les caisses à tortues sont déjà installées sur le pont, obstruant ainsi tous les capots et ouvertures de la cabine et transformant leur vaste chambre aérée en un four infernal. Il va faire chaud là dedans !!!!

Nous levons l’ancre immédiatement pour les Glorieuses. Arrivée en fin de matinée le lendemain. Les scientifiques se mettent aussitôt au travail. Deux équipes se mettent en place ayant chacune des objectifs bien différents.
On the program, collection of small fish, capture and luggage of young turtles for a first team. Diving and hyper spectral manipulation for the second team.
And of course, at night the two teams are mobilizing to survey the Glorious beaches in search of large female turtles that will be captured, boarded, parked in crates and released with an Argos tag on the back at a hundred miles of their nesting place.

The first sleepless night is fruitful: 6 turtles are already caught. Immediately embarked and swaddled in their big rice bag, they find themselves wisely stuck in their crate. The time to stick the last beacons and put the last magnets, we leave the Glorious at sunset for the first rotation. Due to the risks of piracy that currently exist on the Seychelles islands, we opt for a south-west route. The wind is favorable and we sail a good part of the night. At noon, the next day, the 6 turtles are released and find with happiness their natural element. Argos tags have been activated, tracking can begin ...

Après une nouvelle nuit de nav’, nous retrouvons le mouillage des Glorieuses. Et le travail des scientifiques reprend. Le « jumping turttle » fait toujours autant d’émules et tout le monde à l’occasion de s’essayer avec plus ou moins de succès à ce sport désormais bien connu d’Antsiva : activité qui consiste à courser en annexe des tortues juvéniles, puis à leur sauter dessus et à les capturer en attrapant leurs pattes avant.

After 6 days at Les Glorieuses where each team works intensively, it is time to schedule the second night of turtles. This time, two nights will be needed to catch the 6 turtles. And this year, the handling of these large animals are not facilitated by the military tractor.
Mais l’équipe commence à être bien rodée et la deuxième rotation s’effectue sans soucis. Est ce sous l’effet de la chaleur et de leur journée supplémentaire passées dans les caisses, mais les tortues sont particulièrement sages et tranquilles et noue ne les entendons pas de toute la traversée. Après les avoir relâchées au petit matin, Antsiva met le cap sur le banc du Geyser où de nouvelles manipulations hyper spectrales sont programmées. Pendant ce temps, l’équipe d’Ifremer chasse les petits poissons. Pas facile de flécher des poissons dont la taille n’excède pas 2cm !!!

Et c’est le retour vers Madagascar. Pour la dernière soirée, nous mouillons à la Baie des Russes où Mayeul et Jean-Pascal vont fêter dignement leurs anniversaires : ¼ de siècle pour le premier, le double pour le second. Soirée arrosée avec un cadeau spécial pour Mayeul et tous les jeunes fous du bord : Jérôme, Hugues, Mayeul et Rafaël se lancent dans une partie de surf et wake tirés par l’annexe sous le clair de lune de la baie des Russes. La nuit retentit de leurs cris de joie et nous distinguons leurs silhouettes évoluer dans des gerbes de planctons fluorescents. Magique !