Expedition Australia update – What about Ned?

Tagged off Cairns, Ned the tiger shark was tagged off
Cairns as part of Expedition Australia (Image: Rob Snow)

This February, we joined forces with OCEARCH and other researchers to tag tiger sharks along the Queensland coastline. Battling huge seas and shy sharks, we managed to tag 8 tiger sharks. Six of these sharks were tagged off Cairns, and they continue to ping in. See where they are now at OCEARCH.org.

Ned spent around 5 weeks within the Great Barrier Reef
before heading out to deeper waters - a pattern we have
seen before in other tiger sharks

At the moment, we are intrigued by the shark we named Ned. Ned is a 2.3 m (7½ ft) immature male that we tagged at Batt Reef. Since then, he has meandered along the Far North Queensland coastline before recently moving well offshore into depths of more than 2000 m (6 000 ft).

Ned’s big, open ocean move is very interesting to us, as it is similar to the movements of some of the sharks we have tagged at Raine Island. These Raine Island sharks spend time in shallow reef areas, before moving continuously across large distances over the deeper waters of the Coral Sea. They then return to Raine Island, where their movement is comparatively reduced. For example Zoe, an immature female moved out into the Coral Sea and across to Papua New Guinea 400 kms away, before returning directly to Raine Island. Over the course of a year, an immature male shark moved back and forth from the reefs edge into the deep waters of the Coral Sea, continually returning to Raine Island. Check out his track over bathymetry map in the video here.

Why they make these excursions is unknown, but we suspect they may be searching for a food source. We need to tag more tiger sharks to see if movement patterns vary between juveniles and adults, males and females and so forth. This information will help us to understand what is driving such movements.

Given the interesting tracks of these sharks that moved out into the Coral Sea, we follow Ned with great interest to see where his journey will go.