Where do you spend your lost years, little turtle?

In late October, a collaborative team of researchers from Two Oceans Aquarium Foundation and Upwell took a boat into the swift Agulhas Current, the southwest boundary current of the Indian Ocean that runs down the east coast of South Africa. There, they released 12 tiny loggerhead turtles with satellite tags attached to their carapace (top shells) in an effort to understand how these turtles are using this oceanic highway. Can they swim through it? Does their positioning influence which ocean basin they end up in? What a wonderful opportunity to learn of time that is otherwise lost to the ocean’s depths.

Hundreds of thousands of tiny loggerhead turtles have been observed scampering down the moonlit beach to the waiting ocean, where they hitch a ride in the swift and south-moving Agulhas Current. For many of these hatchlings, this marks the beginning of the “lost years” when very little is known about their movements. But for others, a few months and 1500km later, their journeys are disrupted by cold temperatures and rough seas. They end up stranded along the beaches of the Western Cape, where their chances of reaching maturity narrow down to almost nothing.

These little turtles lie stunned (and often covered with barnacles) on the beach until a gentle hand reaches down to offer them a sanctuary. This is the Turtle Rescue Network – heartfelt helpers who transport this precious cargo to the Turtle Conservation Centre (TCC), where a brighter future awaits. It’s a miraculous second chance.

When they’re ready, the turtles are released back into the ocean – bigger, stronger, and with a fighting chance. The TCC has released over 1 000 young loggerheads to date. But, again, the question arises: Where do you spend the first decade of your life, little turtle? That is why the TCC and Upwell teamed up to track these tiny turtles on their oceanic journey.

This collaborative effort requires partners in different spheres and with a multitude of skills - and so an extraordinary team is assembled! This includes the custodians of the turtles’ natal beaches (iSimangaliso Wetland Park and Ezemvelo KZN Wildlife), the local rehabilitation partners who assist with transportation and turtle care (SAAMBR), the coordinators of the Lost Years Initiative to tag juvenile turtles and better understand their lives at sea (Upwell), the advisors on weather modelling (BayWorld), and advisory oversight (Professor Ronel Nel). By combining their individual strengths and knowledge, this powerful team is helping us to understand how these little turtles use their ocean habitats.

Let’s start by seeing where these 12 tagged turtles have spent their first two weeks back in the ocean.

The turtles were released into the Agulhas Current and can be seen moving in its narrow and swift (one metre per second!) path - with a couple of exceptions. Kagiso made a quick exit into an eddy, an area where part of the current had peeled away in a circular motion. You can identify eddies in the map above by the dark blue curls of fast-moving water to the right of South Africa’s east coast. After swimming in a loop, Kagiso seems to be heading back to the main current, but time will tell! Meanwhile, Tao hung out with fellow hatchlings a bit longer before departing directly south, crossing through some smaller eddies and then changing direction again to head northeast.

The other turtles continued down the current towards the Cape, where the Agulhas retroflects, making a sharp turn towards the Indian Ocean. It seems that Parker has followed this path, and will likely be carried into the South Indian Ocean Current. Lesedi, Tolkien, Taylor, and Mpho have departed north of the current, seemingly avoiding the retroflection zone. If they continue west, they may end up in the colder Benguela Current that flows up Africa’s West Coast towards the Equator. Rory, Bailey, and Benji all appear to be within the grasp of the retroflection zone, and their paths could take a (literal) turn. Due to the dynamic nature of this oceanic zone, all our predictions remain hypotheses; we could see sharp heading changes at any moment for any of these turtles.

In the map above, the turtles' tracks are shown over the Sea Surface Temperature, exhibiting the difference between the waters off their natal beach and where they are now. The waters around the Cape are colder and rougher - this is where most of these turtles were stranded the first time they made this journey just a few months ago in April. Their tracks are showing us valuable insight into how rehabilitation efforts, like those of the TCC, can benefit juvenile turtles after being stranded. Only Remi has yet to reach the retroflection zone, and with various turtles making spectacular changes in direction, there really is no telling where most will end up yet. Follow us to find out if they venture into the Atlantic or Indian Ocean!