Prawn Population Rising in the Swan River

By Nicola Blacker Once an iconic pastime for many people in Perth, prawn fishing in our major rivers is now subject to strict regulations due to a decline in numbers. The Swan River Trust is trying to change this via Prawn Watch, an initiative developed by River Guardians, which aims to increase the population of the Western School prawn in the Swan and Canning Riverpark. Beginning in 2012, this multi-organisational effort has resulted in the successful cultivation and release of more than 105 000 prawns says Greg Jenkins, director of the Australian Centre of Applied Aquatic Research (ACAAR) at Challenger Institute. “This was a pilot project that set out to develop techniques to release and monitor species, looking at how governments might restock on a much larger scale,” said Mr. Jenkins. We had to work out how to grow this particular species of prawn and cultivate it. Normal methods don’t apply to this species as Western School prawns are so small.” James Tweedley, a postdoctoral research fellow said Murdoch was specifically focused on understanding the biology and ecology of the Western School prawn. “Murdoch’s role in the multi-organisational project is to monitor prawn populations in the Swan and try to elucidate why the prawns declined in the past,” said Dr Tweedley. “We are looking at spatial and temporal patterns in prawn abundance, the growth and reproductive biology of the prawn and which predatory species in the Swan-Canning Estuary eat it,” said Dr. Tweedley. With the project in its third and final phase, the ACAAR is aiming to release more than one million Western School prawns into the Swan and Canning rivers this season. Prawn Watch is open to the public and encourages citizens to get involved to monitor the prawn population by registering as a River Guardian. Free training is then provided by the Swan River Trust which will teach volunteers how to recognise western school prawns, record their sightings and fish sustainably. To find out more about the Prawn Watch project, head to the River Guardians website.