Tracking Bob: Loopy ocean rollercoasters!

Update #11: 14 April 2023, by Talitha Noble

Bob, the green turtle, was released in KwaZulu-Natal 77 days ago! That's 77 days of wildness and exploration in the big blue ocean!

During this time, he averaged 58 km per day, covering a distance of 4 400 km! Bob has reached these impressive daily distances because of his smart swimming and willingness to go with the flow. This is a quality that the turtle team noticed from the start of his rehabilitation journey - Bob is a very chilled, savvy swimmer!

As you can see in the swirling patterns of his tracking progress, Bob is letting himself be carried by the circular currents. The water is quite calm at the centre of these currents, with little movement or wind. But as you move out of the central space, the current speed increases quite quickly and can reach speeds of 1.5 m/s. This is the same speed as the fast-moving Agulhas Current.

Now, Bob is exhibiting similar behaviour to when he was cruising down the Agulhas Current after his release. Bob, while not in the fastest part of the current, is swimming in a spot that substantially aids his speed and decreases the effort required. He has made three big loops in the last three weeks. Classic Bob...

However, these surface currents change direction and speed quite quickly, so it will be interesting to see if Bob continues to loop in the Atlantic Ocean or decides to move in a clearer direction.

Bob's current "looping" behaviours are very similar to Caddy, a young loggerhead turtle released in July 2022. Caddy also zoomed down the current and made some ocean loops!

Bob is currently 420 km offshore and in water that is 4600 m deep. This depth doesn't refer to his diving depth but rather the depth of the water that he is swimming through. Adult green turtles can dive hundreds of metres deep, but they spend over 80% of their time in the top two meters of the water column.

We are super excited to see what Bob gets up to next. The battery life on his satellite tag won't last forever, so we may not be able to track his movements for longer than a few years. Luckily, Bob is also equipped with an acoustic tag, thanks to the support of the Acoustic Tracking Array Platform (ATAP). Acoustic tags have an incredible battery life of 10 years! This means that we will be able to track Bob's movements around southern Africa for another decade.

Turtles doing rollercoaster current loops in the ocean are just the best! Well done, Bob, for having a good time! Stay in the loop to see what Bob gets up to next...

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During his eight years at the Two Oceans Aquarium, Bob inspired hundreds of thousands of people to love the ocean and its abundant life just that little bit more. Now that Bob has returned to the ocean, he'll continue to be an incredible turtle storyteller as he sends back data about his adventures. Meanwhile, we'll do what we can to protect his ocean home.

If you missed out on any part of Bob's story, you can catch up here:

• View all previous Bob updates here
• What did it take to release Bob safely?
• How do tracker tags work?
• Why was Bob at the Two Oceans Aquarium?