UP until a couple of years ago, James Tweedley marvelled at how well a project to breathe new life in an age-old practice on the Swan River had been going.
Through a partnership between Murdoch University and the Swan River Trust, Dr Tweedley had been spearheading groundbreaking work to restock Perth’s major waterway with western school prawns.
Between 2013 and 2016, researchers released more than 4.6 million juvenile prawns into the river system, and watched with delight as the crustaceans’ population multiplied.
Visions of reviving Perth’s summer tradition of prawning on the Swan were well and truly on track.
But then, as Dr Tweedley noted, the Swan was hit by two unusual weather events — a cold winter that sent water temperatures two degrees lower than normal and an extreme downpour in early 2017.
The upshot is the “schoolies” prawn population is more or less back to where it started, prompting Dr Tweedley and Murdoch to call for a shake-up of the species’ management to ensure it is better protected.
The episode serves as a reminder of the problems that have long bedevilled the Swan and Canning River system.
For all the good work to improve its condition, the Swan remains chronically exposed to environmental events and the effects of urbanisation.
Pat Hart, a former director of the trust who is currently the chair of the South East Regional Centre for Urban Landcare, said she was worried about the state of the Swan.
Ms Hart said the decision by the previous government to axe the Swan River Trust as a stand-alone entity and roll it into the broader public sector was a big mistake that would come back to haunt politicians.
She said the dismantling of the trust robbed the river of its guardian and biggest advocate.
“It’s just disappeared and so all the fabulous staff have all melded into the (Department of Biodiversity, Conservation and Attractions),” she said.
“It’s been abandoned and it is disappointing, particularly with all the knowledge that’s gone.”
Of particular concern to Ms Hart was the absence of information about the health of the Swan — she said it was now harder than ever to know whether it was in good condition.
To that end, the DBCA defended a decision to stop providing monitoring results for nutrients such as nitrogen and phosphorous and indicators for the river’s ill-health such as chlorophyll-a in the trust’s annual report.
The department said the data would be included in a biennial report to be released in the coming weeks that was deemed a “more appropriate mechanism”.
Chris Ferreira, director of the Forever Project and a landcare expert who has delivered programs to reduce nutrient inflow into the Swan for the trust over more than two decades, echoed Ms Hart’s misgivings.
Mr Ferreira said progress had been made addressing some of the causes of the Swan’s problems but for every step forward there seemed to be a step back, with the chief among those the move to disband the SRT.
He said the decision was short-sighted and would eventually be overturned when the inevitable next environmental disaster to affect the river, such as a mass fish kill, happened.
“To be fair, governments have run fantastic programs in the past and we have been a beneficiary of being able to teach that,” he said.
“But the foot has come off the pedal and it’s a major problem.
“So at a time when we desperately need to keep ramping this up, we’re going in the wrong direction.”
Key to fixing the Swan’s underlying problems, according to Mr Ferreira, was educating land users such as farmers but also householders in the city to be smarter about their way used nutrients.
Too often, he said, the default practice was to spread fertiliser such as nitrogen and phosphorous over paddocks or gardens despite the fact local soils were notoriously water “repellent” and most of the nutrients were simply washed away.
Mr Ferreira said this was not only inefficient but also environmentally harmful, because those nutrients invariably ended up in the Swan and Canning Rivers through the drainage network.