Restocking and Monitoring the Fishery
The Department of Parks and Wildlife, the Department of Fisheries, the WA Fish Foundation, Recfishwest, ACAAR at Challenger IOT, Murdoch University and the Fisheries Research and Development Corporation continue to work together on various aspects of the Western School Prawn restocking projects.
The western school prawn culture work by the Australian Centre for Applied Aquaculture Research (ACAAR) at Challenger Institute of Technology (IOT) achieved a world first in 2012 when they successfully cultured the school prawns. Since then juvenile school prawn release rates have been bolstered as staff have gradually refined their techniques and knowledge across the breeding projects.
Challenger released 635,000 school prawns in 2014, almost 2 million school prawns in 2015 and a further 1.8 million school prawns during 2016. This makes a combined figure of 4.5 million prawns released!
The citizen science project and western school prawn restocking are also linked to a university based research and monitoring effort. The more we can learn about the western school prawns and the effectiveness of the restocking projects the more chance we will have of enjoying the recreational fishing benefits the Swan Canning Riverpark can provide.
Data from researchers, brood stock collectors and Prawn Watch volunteers has already led to some fascinating insights into western school prawn predation, movements and culturing.
History of Prawning in the Riverpark
A commercial prawn fishery operated historically on the Swan and Canning rivers. It harvested 14 tonnes of prawns at its peak in 1959 before falling to three tonnes in the late 1970s when the fishery was abandoned.
The recreational fishery has continued but the decline in catch and as a result enthusiasm for it has dwindled since the 1980s.
In 2006, the Department of Fisheries surveyed the abundance of Western School Prawns. Their report showed a much lower abundance than the comparable 1977-85 population estimates, highlighting a long-term recruitment failure.
The factors behind decline of the Western School Prawn are not well understood. The Department of Fisheries has suggested that environmental factors such as water quality change, and not fishing pressures, is the most likely cause of the decline of Western School Prawns. However, this is not proven.
There are a range of factors that may be contributing to the decline including fishing during the breeding period, an isolated population that was reliant on self-replenishment, changes in river flows, reduction in point source nutrients and predation.