“A population-specific instinct to migrate to Ascension Island is thus proposed to have evolved gradually over tens of millions of years of genetic isolation.” ~ Bowen, Meylan and Advise in “An odyssey of the green sea turtle: Ascension Island revisited”*

Silent Depths
by Stephanie Pui-Mun Law (used with permission)

                   

Reprinted from Mysterra Magazine on the Giant Sea Turtles of the Island of Ascension:

The green turtles (Chelonia mydas) have been the emblem of Ascension for more than 200 years. The island would not have been the same today without their presence in this region. Once, they were the main motives for which ships were anchored the island’s coast for a few days. Indeed, the turtle was an important source of fresh meat for the ships passing through Ascension. They were kept in ponds at Georgetown and later on, were transferred alive on the ships. Today still, they are often the main goal of visits in the island, but fortunately for entirely different reasons: observation and scientific research on this nearly extinct species.

Every year, the green turtles, both male and female, migrate from Brazil to Ascension and thus swimming a total distance of more than 2’000 km across South Atlantic. We are unaware of the reason for which these turtles lay their eggs on this small island, nor how they succeed in finding such a tiny plot of land in the ocean. Turtles marked previously with distinguishing signs have proved that Ascension is not a random choice; the same turtles can be seen on the island year after year.

A certain theory leads to say that this migrating itinerary dates back to million of years ago and has been developed when South America was detached from the African continent. Nevertheless, it is said to have remained deeply anchored in the memory of the turtles. Other scientists are of the opinion that they follow oceanic currents. However, their instinct must have been acutely developed to distance them from their native grounds for a 4’000 km round trip without any food.

Every year, the basic estimate is that 3’000 to 5’000 female green turtles lay their eggs on the beaches of Ascension. This is surely a representative of the biggest colonies in the Atlantic Ocean.

                   

*An odyssey of the green sea turtle: Ascension Island revisited

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2 comments on ““A population-specific instinct to migrate to Ascension Island is thus proposed to have evolved gradually over tens of millions of years of genetic isolation.” ~ Bowen, Meylan and Advise in “An odyssey of the green sea turtle: Ascension Island revisited”*

  1. Leah in NC says:

    This is pretty cool. I’m glad that people are trying to turn things around for sea turtles…

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