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A research project that involved tracking black bream on the South Coast has found some fish will swim up to 10 kilometres up and down the estuary and river.

Researchers, Paul Close and Dave Tunbridge, from The University of Western Australia's Centre of Excellence in Natural Resource Management based in Albany, have been studying the effects of increased salinity on black bream in the Wellstead Estuary and Bremer River on the South Coast.

In early 2008, they caught 25 adult black bream and surgically implanted acoustic transmitters.  Ten loggers distributed along the river and estuary automatically recorded the positions of these fish every two minutes.

The data collected has now been analysed and indicates that black bream are highly mobile.  Some fish made movements of up to 10 kilometres up or downstream over a period of two to three days, sometimes every two weeks.

Other individual fish tended to live in a particular area and make much smaller movements within their home range.  Most fish moved downstream as the water in the estuary became fresher.

"This research is important in understanding increasing salinity levels in rivers and estuaries, one of the consequences of climate change, on local fish populations," Research Assistant Professor Paul Close said.

"We now have an understanding of the importance of the lower salinity habitats in the upper reaches of the estuary in sustaining fish populations under a drying climate," he said.

The Jack Family Charitable Trust, the Department of Water, Great Southern Development Commission and The University of Western Australia supported this project.

Richard Grist, a trustee of the Trust, said the Jack Family Charitable Trust was pleased to be able to contribute to a local project that would benefit the management of an important environmental, social and economic regional resource in the longer term.

Media references

Assistant Professor Paul Close (+61 8)  9842 0833  /  (+61 4) 24 004 449
Janine MacDonald (UWA Public Affairs)  (+61 8)  6488 5563  /  (+61 4) 32 637 716