Barotrauma - 'the bends' in fish to be studied by NSW Scientists

by NSW Government on 30 Nov 2010 Industry & Investment NSW scientists are going high-tech in their quest to understand a potentially lethal problem in fish - barotrauma.

Barotrauma, sometimes referred to as ‘the bends’, is the physical damage caused by the change in atmospheric pressure when fish are brought to the surface.

The gases trapped in the fish’s blood, tissues and swim bladder expand faster than they can be expelled and can cause injury.

I&I NSW Senior Research Scientist, Dr John Stewart said for the first time in Australia, staff at the Cronulla Fisheries Research Centre have built a specialised hyperbaric chamber that will allow them to recreate the environment at water depths of up to 70 metres.

'These experiments will simulate the pressure change experienced by fish when captured in the wild and will enable scientists to assess the effect on the fish’s physiology,' Dr Stewart said.

'This study is investigating the severity of these injuries in key offshore species in NSW, including the iconic snapper and mulloway,' he said.

Dr Stewart said catch and release fishing is a practice designed to enhance the sustainability of fish stocks, but fish that are captured from even quiet shallow waters can suffer from barotrauma injuries.

'We are researching ways of minimising harm to fish and ensuring that these key species survive when they are released back into the water,' said Dr Stewart.

Dr Stewart said the research will involve both field and laboratory components and will examine the popular methods of reducing barotrauma, venting and release weights.

Some anglers vent or release air from the swim bladder by using a hollow needle and others use heavy release weights to lower the fish back to depth.

'The field component will involve observing the behaviour and survival of fish following their capture from various water depths and subsequent release. The observations will be made using state-of-the-art acoustic tagging technology,' Dr Stewart said.

'This technology will enable observations to be made of the fish in their natural environment,' he said.

Dr Stewart said some snapper will be tagged with long-term acoustic tags to monitor their behaviour and movement throughout the year.

The research is being funded by the NSW Saltwater Recreational Fishing Trust and I&I NSW.

For more information, please go to: www.dpi.nsw.gov.au