What are yo-yo movements?

 

Yo-yo movements are continuous dives used by tiger sharks. The above depth plot shows just one hour of depth data from a 3.5 m female tiger shark. As you can see, she is constantly moving up and down. Video from this individual showed that she always reached the sea floor on the bottom of each dive. 

Our advanced tags with cameras will help us work out why tiger sharks do this. So far we have managed to record some interesting behaviours such as encounters with sea turtles (a preferred meal item) during our tag deployments. The screenshots below show one such encounter where a turtle is spotted at the surface (top) and manages to escape one minute later at the seafloor (bottom).