Sat Tagging Green Turtles on Ascension

Satellite Tagging Green Turtles 

On the 18th February three shark scientists Sam, Dave and Nigel, arrived on island to assist with the shark tagging programme here on Ascension. Sam was a lecturer at Exeter Uni during my masters and is a former director of AIG Conservation. 

 Some exciting news was that whilst he was here we were also going to get the chance to satellite tag some turtles to track their migration back to Brazil! I was very excited when I heard about this as I’ve wanted to sat tag a turtle for forever! 

The tags arrived at the end of February with the application kits arriving a little while later. We have 2 splash tags and 20 Spot tags – half of which will be deployed this year and half they will use next year. 

The Splash tags being slightly more expensive/record slightly more information. 

Wildlife Computers Inc. - SPOT Transmitting Tags : https://wildlifecomputers.com/our-tags/spot-argos-satellite-tags/spot/ 

Wildlife Computers Inc. - SPLASH10-F-385 Product Information  

https://wildlifecomputers.com/splash10-f-fastloc-gps-tags-product-sheet-splash10-f-385/

The application kits include:

• sand paper 

• nitrile gloves 

• two part quick setting marine epoxy 

• 10 minute repair epoxy 

• Disposable brushes 

• Fibreglass cloth 

 • Devcon adhesive dispenser 

 • Disposable mixing cups and sticks for mixing epoxy 

Tagging

On the 12th March Abi, Anna and I headed over to Hayes House to help Toby prep the tags for the nightwork and tag deployment. The tags each had to be sanded down (protecting the wet and dry sensors), wiped down with acetone (to clean and dry them) before being painted with anti-fouling paint to reduce the amount of growth of benthic settlers on the tags which could affect their ability to function over a long period of time. Before painting them we also had to create a small window on the side of the tag so that we could still see the small flashing light used to communicate with the tag before deployment (using a magnet to provide the tag with instructions). Toby had set the tags to standby mode (Auto start) earlier that day. We also made sure to write the serial numbers of the tags on the label on the bottom so each tags ID could be recorded in the field before deployment. Our anti fouling paint was a brownish burgundy colour and we made sure to paint the entire tag, including the antennae without painting the sensors or window. 

On the 14th March Anna, Marcos, Lorna, Toby, Sam and I met at the office at 20:30 ready for an evening of turtle tagging. Toby checked we had all the tags and kit we needed for the tagging process whilst Anna and I got some head torches ready. For the purpose of tagging, a turtle box had also been made up a few months earlier by Jaco based on average turtle measurements from previous years data – the box is made of 4 planks of plywood which slot together in three places to be suitable to contain smaller, medium sized and larger turtles that we could come across. This was packed into the car alongside the tag application kits and the tags themselves. 

We reached the beach just after 9pm and split up along the beach to look for a turtle who was digging an egg chamber or laying eggs. We found a turtle digging an egg chamber with quite early on and I waited with her whilst the others continued on to see If they could find one at the egg laying stage (this is because when they are egg laying the Oxytocin hormone puts the turtles into a trance like state which means we can carry out data collection etc. without disturbing the turtle). 

Anna also ended up waiting with a turtle who was digging an egg chamber, but her turtle abandoned. My turtle started to lay eggs so I notified Toby and Sam but they were also with a turtle who was laying, and Sam was trying to take blood samples so we all headed over to Sam and Toby. When the turtle began covering her egg chamber Anna and I took the CCL and CCW measurements and Sam then also took two small scute samples from the right side of the turtle. These were taken from the 2nd scute down, one core from the top left corner and one from the bottom right, which are the oldest growth and newest growth points. 

These samples will then be used for stable isotope analysis. He then also took a small epithelial sample (biopsy) from the front flippers from between the 3rd and 4th Scales at the bottom of the flippers also for stable isotope analysis. 

We then had to wait for the turtle to continue covering her egg chamber and complete the camouflaging process which can sometimes be very quick and other times can take a very long time (with some turtles being recorded to take up to 4 hours to complete a cover up!). Our turtle took just over an hour to finish her camouflage before she began to return to the sea. As she exited her turtle pit/turning circle we put together the front three panels of the turtle box for her to head into and Anna and I oversaw following up behind with the back piece to slot in once the turtle was in place. 

She was a little stubborn, so we had to move the box slightly more towards her but eventually got her into position and closed the box around her. Sam tagged the first turtle, talking through each stage whilst Toby mixed the glues and passed everything over as it was needed. 

The first step was to sand her shell in the place where the tag would be attached, then the area was wiped with acetone to make it clean, remove any oils and dry. Then Anna, Marcos and I helped hold down the turtles’ front flippers to stop her from flicking sand onto the area where the glue was going to be applied. At this stage we used white light as we needed to be able to see properly what was happening for attaching the tag, but normally we only use red light on the beach. Next the first layer of Epoxy glue was applied to her carapace using a small paint brush in a rectangular shape. Then a rectangle of fibreglass sheet (+50% the size of the tag) was placed onto the glued area and secured down, and then glue was applied over the top of this as well. 

Once that became tacky and drier the epoxy putty was prepped by being warmed up in Toby’s hand and worked to make it more malleable. This took around two minutes and then the slip on the bottom of the tag was removed – the numbers being written down and two sausage shaped pieces of the putty were stuck to the bottom of the tag. The tag was then positioned on the carapace and pressed down so the putty was exposed around the edges, it was then pressed and worked around the edge to form a more aerodynamic shape and seal the edges of the tag onto the carapace. 

Once this became slightly harder and drier more epoxy glue was applied around the edge of the tag, first along the back edge, then covered in a strip of carbon fibre, then glued over the top again making sure to cover the edge and side of the tag as well to seal it all in. Then this was repeated for the two sides and top edge of the tag until all edges were sealed in with glue. We then had to wait until the glue had dried slightly again and was less tacky before painting anti fouling paint around the whole base we had created and around the edges of the tag. 

The glue overall then needed another 45 minutes to dry fully so Marcos and Lorna waited with the Turtle still in the box whilst Toby, Sam, Anna and I went and looked for another turtle who was laying to repeat the process again. 

Anna found a turtle laying not too far from where the first turtle was, so we began the process and Sam tried to take some blood samples but wasn’t having much luck. Once she started covering up Anna helped take the biopsy samples and I measured the CCL and CCW. The first turtle was released from the box and made its way to the sea and the box was brought over to our new turtle. This turtle’s camouflage took an hour and the Sam and Toby swapped roles when it came to tagging her. I made sure to pay extra attention as Sam had mentioned I might be able to tag the third turtle of the evening. This second turtle moved a lot when we had her in the box, so it took a lot of our strength to keep her flippers down to stop sand getting into the glue. 

Once the 2nd turtle was tagged, we then looked for a third, I found one laying and we gathered by her, and Sam said I could do the tagging if I was happy to. Samples and data was collected again and then we waited for what felt like an eternity for her to finish her camouflage! By the time she finished it was 3:30am! She had created a very large cover up though. We got her into position in the box and then I was handed the sanding block to sand her carapace. 

I then followed all the steps Sam had down us with Toby dealing with the glue and handing me what I needed. To help stop her moving around too much I also had to apply pressure to her carapace with my body weight a little – which felt very weird because it was a bit like sitting on her but also was a bit of a leg work out trying not to apply all my weight on her. It was an amazing experience to get to tag her though. And I decided she’s unofficially named Lulu 😊 after the turtle at Brighton Sealife we used to visit when I was younger. Whilst I was applying the glue for the tag a couple of hatchlings also were making their way to the sea and it was incredible to see how tiny they look next to the adults. By the time I finished painting the antifouling paint it was past 4am and so Toby and Lorna stayed with the turtle to release her later whilst Anna and I headed off back to the house ready to be up in two hours for work at 7:30am raking! 

A naming system hasn’t been put in place yet for the tagged turtles but we might use it as an outreach activity or get the MPA youth Committee involved in naming them so mine might not be called Lulu. We successfully tagged three turtles that evening, and a second night of tagging took place the night after, where two were tagged but I was not involved. And I think the plan moving forward is for Toby to lead tagging in April where 7 more tags are planned to be deployed. 

UPDATE: You can actually track the turtles here: https://my.wildlifecomputers.com/data/map/?id=6414515531af59226019f633 

My turtle is the one that ends in 217 – I will update this if she is renamed once the school kids vote on the names. 

Dr Sam Weber also gave us three accelerometers (movement loggers) to deploy into nests on Long Beach, these are for a study looking at whether the small peak and then sharp drop in temperature seen when recording nest temperatures (usually assumed to indicate a hatching event when looking at temperature curves plotted from temperature logger data), is an accurate way of determining hatching dates and incubation length, by recording movement to see if that correlates with the time of the temperature change. Abi deployed the first logger in the 10th nest on Long Beach (23rd February) the temperature logger is deployed around halfway through the laying with the movement logger deployed right on the top of the eggs just as the turtle is about to cover up the eggs. The 2nd and 3rd were also deployed on Long Beach during Sat tagging on the 15th March in nest 11 and 12.