The nesting season has most definitely come to an end and we are in the midst of hatching season. Thus far we’ve calculated the average amount of eggs deposited by a nesting female at 97 eggs. After a nest is laid it is left to incubate for around 55 days, although our average incubation period this year is 53.8 days. Once the nest is ready to hatch a few hatchlings begin to break their through their shells. These vibrations alert the rest of the hatchlings to also begin to come out of their shells. Hatchlings dig out of nests collectively, with the hatchlings on the bottom of the nest pushing the ones at the top out. Sometimes a nest can hatch in one night, while other times it takes up to six days. For this reason we do not excavate a nest until the 7th day of hatching.
Excavations are necessary to allow us to collect important data and to free trapped hatchlings within the nest. Thus far we’ve excavated 58% of our nests (44 out of 76). When we conduct an excavation we take out and count all the hatched and unhatched eggs. We then open up all unhatched eggs to categorize what stage their development were terminated. Over 70% of all unhatched eggs had no visible embryo meaning that it was most likely not fertilized to begin with.
We can also calculate each nests hatching and emergence success rates. Hatching success of a nest means how many eggs hatched out of all the total eggs within the nest. Our average hatching success rate for this season is 63%. Emergence success rate is how many hatchlings successfully emerged out of the nest, as not all hatchlings make it out of the nest after they have broken through their eggshell. The average emergence success rate for all hatched nests is 54%. This value is low and is due to the severe amount of inundations we’ve had the past two weeks. These inundations compact the sand above the nest and can ultimately suffocate the embryos.
There have been six strandings/rescues since the last roundup article; four of them were due to entanglement in fishing lines and hooks. Of those four, two were found dead due to the fishing gear. This stresses the importance of our daily harbour shift as all injured/entangled harbour turtles are found alive and our team is able to help them immediately, whereas outside the harbour they have already died due to entanglement or anthropogenic activity. Circe and Chronos are still at the Athens Rescue Centre readily awaiting surgery to remove the hooks they’ve ingested.
Artemis was re-captured to confirm her identification and return to the Argostoli Harbour after her surgery last year. We are very pleased about this and can’t say that we are surprised as sea turtles are able to migrate over thousands of kilometers and are skilled at locating specific coordinates stored in their memory. Bulbious was also captured earlier this week for Dr.Vavasi to take a fine needle aspirate in order to further investigate the ever-growing lump on his neck. We’ll hopefully have the results in a few days as they have been sent off to an external lab.