Tracking fish in the South Alligator river system

Radio-transmitters were surgically implanted

Movements have been tracked by boat and helicopter every two weeks since the fish were released

Wouldn’t it be amazing to follow a fish in a vast area like Kakadu National Park?

We’re working with researchers from the National Environmental Research Program (NERP) who are mapping Kakadu’s floodplains and the movements and behaviours of fish in their waters.

By learning more of the fishes’ movements we can develop our understanding of how the ecosystem functions. The results from this research will ensure that policy and management decisions regarding our fisheries and their habitats can be made using sound scientific evidence.

In October NERP tagged 40 barramundi and 30 catfish and then began tracking their movements throughout the wet season. The fish are being tracked every two weeks until June.

We know that the floodplains are a very important habitat for barramundi at certain stages in their life cycle -  for example when they are growing and reproducing. But we don’t know how long individual fish remain on the floodplain, how far they move, whether there are particular areas or types of habitat the fish prefer, and what they do once the floodplains begin to dry out. This is essential information to ensure Kakadu’s wetland biodiversity is protected, and to plan how water will be managed in the future.

The fish were caught in Yellow Water, a tributary of the South Alligator River, the largest river system in Kakadu, which contains extensive wetlands. The results so far are fascinating, painting detailed pictures of fish moving back and forth in Kakadu’s river, side-channels and wetlands. Following the first major rainfall in early December, there was a big spike in fish movement, with some moving several kilometres out onto the floodplains and even disappearing altogether from the 3,000 square km area being surveyed by helicopter. Barramundi moved up to 50 km and the catfish moved up to 20 km.

NERP are continuing to update their website with the fish movements. The scientists are particularly interested to see how the fish behave when the floodplains begin to dry up.

Anne, Kakadu National Park