Ascension : Ascension Island Conservation Department
Submitted by The Islander (Conservation Office) 03.05.2012 (Article Archived on 17.05.2012)
As many of you will remember, we have been tracking a number of green turtles this year using radio- and satellite-telemetry tags to try and find out how many times they nest on Ascension’s beaches.
Ascension Island Conservation Department
Tagged turtles head back to Brazil!
Contributed by Nicola and Sam Weber
As many of you will remember, we have been tracking a number of green turtles this year using radio- and satellite-telemetry tags to try and find out how many times they nest on Ascension’s beaches. And the final results are now in! Of the 40 turtles we tagged, the majority laid between 5 and 8 clutches (8 being a new record for the island!) with an average of 6 clutches per female. This is double the previous estimate of 3 clutches per turtle obtained in 1987 using flipper tags alone, and has important consequences for our population size calculations. Each year we estimate the number of female turtles visiting Ascension by dividing the number of nests counted on the beaches by the number of times each female lays. Since each turtle lays twice as many clutches as we previously thought, there are probably only half as many turtles nesting on Ascension each year. This is not a cause for concern, as the annual number of nests is still rising at an encouraging rate, but it does show how important each individual turtle is to the overall numbers of nests.
After their record-breaking season, it appears that our tagged turtles have now left Ascension to begin their mammoth migration back to Brazil. Our night time surveys of Long Beach finished this weekend after we failed to detect a radio-tagged turtle for 2 weeks, suggesting that all of our study turtles have now departed. Indeed, we had some exciting news last week when we discovered that one of our satellite-tagged turtles (named ‘Destiny’ by Two Boats School) has arrived safely back in Brazil following a swim of almost 3000 km (see her satellite map below)! At last transmission she was just offshore near to a town called Pablo do Peba. Hopefully her tag will continue to transmit for another few weeks so that we can see how much she moves around and where she selects as her home for the next few years. Now she is back in Brazil, Destiny will fatten herself up on seaweeds and other algae for about 3 to 4 years, before heading back out into the Atlantic to Ascension Island to lay another 6 clutches of eggs.
Satellite map showing Destiny’s route across the Atlantic from Ascension to Brazil (from www.seaturtle.org)
For the next couple of months we will continue with our daily beach counts to get a population size estimate for the number of green turtles nesting at Ascension Island this year. We will also be turning our attention to the critically endangered hawksbill turtles that are found in the waters off Ascension, but do not nest on the Island. We are currently compiling all of the sightings data submitted by the public and Conservation staff for the past 10 years to produce a map of where hawksbills are found around Ascension. We have had lots of sightings at the Pierhead in Georgetown, English Bay, Comfortless Cove, Boatswainbird Island and Pillar/ Cocoanut Bay, but would really like to hear from you if you have seen a hawksbill in any other location recently - either from the surface or when out diving. Green and hawksbill turtles look similar to each other in many respects, but there are some distinct differences in appearance that can be used to identify them (see photos below). The most obvious difference is the size: hawksbills are noticeably smaller than the adult green turtles that nest on Ascension. Hawksbills can also be distinguished from green turtles by their sharp, curving beaks and the saw-like appearance of their shell margins. We are keen to flipper tag and collect DNA samples from more of the hawksbill turtles to try and determine how many there are, how long they stay here for, and which nesting population(s) the juveniles around Ascension originate from. We will get in touch with divers soon about this project, but feel free to contact us if you would like to be involved.
We would like to say thank you to D Company 2 Royal Anglian for volunteering their time clearing paths on the Green Mountain National Park as well help the clear large stones from the new SE Bay Track.
Thank you to Colin Winwood and his family for reporting a stranded Brown Booby bringing it in, we are please to advise that this bird was care for and released by Stedson Stroud last week.
Thank you to Mario Williams , Chris Henry and their families for helping with the turtle stranding Deadman’s Beach.
It is now the land crab breeding season, please take care when driving on roads due to land crabs migrating down to the beaches. Please try to avoid crushing our Ascension indigenous land crab.
Thank you for your co-operation.
Turtle tours can now be booked either at the Conservation Office on telephone number 6359, or via the Obsidian Hotel on 6246. You may also email us on the below email addresses:
Please be advised that due to on-going field work the Conservation Office will open from 7.30am -10am during week days. We open as normal on Saturdays, 10am-12noon, signs will be posted on the door when the office is closed.
Sorry for any inconvenience this may cause.
Volunteers welcome. Please contact Natasha Williams or Jolene Sim. Ascension Island Conservation Department. Georgetown. Tel: 6359. Email: email@example.com or firstname.lastname@example.org