ACCORDING to scientific research, cod numbers are rising in the River Murray, more than a decade after the species was listed as threatened.
Scientist Qifeng Ye works with the inland waters program at South Australia’s Research and Development Institute (SARDI) and has been working to revive cod numbers for almost 15 years.
“During the drought period we didn’t catch these one-year-old fish, so that’s showing that there’s improvement in catch rate,” she told the ABC.
Dr Ye said the flooding back in 2010 had boosted the numbers of juvenile fish since, but recreational or commercial fishing remained a long way off.
Size restrictions, bag and catch limits vary between South Australia, Victoria and New South Wales.
Dr Ye said collaboration between the states had improved, but there were still cross-border anomalies to address.
“Fish don’t recognise state borders and operate on large scales, so it’s good if we have some consistency regarding the management of fish populations,” she said.
“Ideally you should try to recognise the ecological unit and it should match with the management unit.”
The researchers worry reduced environmental flows were a factor in the Murray cod decline and Dr Ye said a three-year trial of control stocking was planned for the river.
“The biggest threat has been highlighted is the river regulation,” she said.
“The fundamental thing is you really need to address the threat regarding the river ecosystem health and environmental flows.”
Changes in habitat, exploitation of the river, invasive species and disease were thought to be other factors behind the previous decline in cod numbers.
Dr Ye said work was being done to restore fish passages, improve habitat and enhance the river flow.
About 25 anglers turned up at Lyrup Flats last weekend to help gather data on the Murray cod population.
More at: http://www.abc.net.au/news/2015-06-16/murray-cod-fish-rise-murray-river/6549322
