Introduction

The marine turtles have a surprising and still relatively unknown way of life. Spending all their life in the sea, except for the grown-up females which appear briefly to come to lay, the turtles are capable of crossing oceans and can wait 50 years before reproducing.
In French Polynesia, the turtles ( honu ) is crowned (tabu ) since the origin of time.
Although protected by the agreement of Washington and the territorial rule, the turtle is threatened with extinction if we are not careful there.

The species

We can observe two sorts of turtles in French Polynesia: the green turtle and the imbricated turtle.

The most frequently met turtle in the lagoon of Bora Bora as well as in the Le Méridien interior lagoon, is the green turtle or Chelonia mydas.
Its name is due to the green color of its fat. The green turtle measures between 80 and 150 cms for approximately 230 kg.

During its first year of life, the green turtle lives near the surface of the ocean where it feeds on numerous plankton: jellyfishe, mollusks … This zoophage diet corresponds to the needs of fast growth of a young animal.
However in Bora Bora the young turtles remain difficult to observe.
At the end of some years, the green tortoises are capable of going to ocean depths and they adapt themselves then to a new way of life.

After several years the green turtles are capable of going to depth and they adapt themselves then to a new way of life. This specie thus becomes bit by bit phytophage with an exclusively vegetarian diet; it feed off seaweed, in very particular sites.
This food is responsible for its slow development compared with that of the other sorts of turtles which feed mainly on maritime animals.

In Bora Bora we never observe any already grown turtle of less than 30 cms of length which implies that the baby turtles return. The period between their birth and their adult size is thus a rather mysterious period for the observers of Le Méridien.
The second present specie in Le Méridien Protection’s Centre is the imbricated turtle (Eretmochelys imbricita) which measures less than 90 cms and weighs on average 50 kg.

We recognize it by the crichu beak and the beauty of the scales. It swims near coasts to feed on crabs, fishes, sponges, shells, etc. No layings observed untill this day in Bora Bora, in spite of their rather important presence.

Reproduction and layings of eggs

According to the scientific studies of other continents, during coupling in sea, the male hangs on to the female’s carapace. However, the coupling does not seem to be made in the Bora Bora’s waters as nobody was until then able to observe it.

The turtles lay on beaches all year round but we notice that in Bora Bora the most convenient periods remain from November till January.

In Le Méridien Bora Bora we can observe the layings of the turtles just behind the hotel. The turtles cross the cliff, the lagoon, exceed the beach and the height of the platier and go to the bottom of the plants of Miki Miki. Females begin their trip at about 6:00 pm to finish their layings one hour and a half later.

Before laying, the female turtles look for the place must appropriate to lay their eggs. Their choice being made, females fit out a wide physical cavity by means of both fins.
In thirty minutes, the layings are finished. However, they can lease at any time because of an abnormal noise, an excessive luminosity …

The turtle fills the nest of wet sand which she compresses slowly with its hind legs. It buries then eggs in 70 cms under the surface.

Then the hind fins dig a hole in the form of bottle where the eggs will be layed. In Bora Bora nests observed on the motu contain about 60 in 120 eggs.

In a season, a female comes to put down its eggs on average three times in more or less ten days of interval according to the observations made in Le Méridien Bora Bora. What was noticed is that the places of laying are separated from each other only by approximately 100 metres.

Exit from the nest

In the sand, the eggs will hatch after approximately 60 days
The temperature of the nest seems to play a very important role.
It conditions not only the duration of incubation but also the distribution of the sexes through the small turtles.

The newborn stay some days in the nest; by movements they displace under them the sand which surmounts the nest and approach the surface.
The place of exit will be determined by the temperature because the newly born turtles require a cool environment.

We can then admire the turtles swimming towards the lagoon, passing above the cliff and going away where they are carried by the sea. They will feed with zooplancton (fishe larvas, shellfishe, cephalopods) to begin their growth.

The threats

The turtles, much more than other animals, by the robust osseous box which protects them and by their longevity, seem endowed with an exceptional robustness.
They appeared more than 200 million years ago; they already existed during the extinction of Dinosaurs in the Cretaceous and survived until our time. Nevertheless following the intervention of man, the populations of marine turtles have not stopped decreasing.
Numerous threats weigh on this specie.

A/ Threats on eggs and babies
Before even its birth, the small turtle risks not to be born. At the most intense moment of the period of laying, eggs are crushed by the other females digging their nests. They can also be attacked by rats, dogs …
Eggs also can be killed by cycloniques tides, torrential rains or drought.
The exit of the nest is also eagerly awaited by the natural predators.
Crabs, Bernard Hermits and especially the predatory fishes feed during the night, on large number of small turtles.
In the daytime, they are systematically the prey of all the more redoubtable and more effective water birds as they have their offspring to be fed.

B) Threats on the adult
The mortality is weaker at the adult stage. Indeed, adult turtles have very few predators but they can be affected by carnivorous species such as sharks.
But the most important threat still remains the human one. Indeed, the turtles are hunted for their flesh as well as for their shell which is used for the realization of objects of decoration.
Furthermore, the increase of the human activities on the coast and their flood on beaches hamper enormously the laying (noise...) Many turtles die also imprisoned in trawl nets and the ledger lines which were not intended for them.
Finally and especially, the waste in the water (polythene bags) can be taken for jellyfishes and eaten by the turtles, which causes their death.