A number of prawn suppliers and importers are under investigation for not meeting biosecurity measures in the time leading up to a disease outbreak.
The Department of Agriculture and Water Services had been investigating the suppliers and importers since August 2016, five months before it became public that white spot disease had been detected in Queensland.
Since December five prawn farms had tested positive for the virus, which causes a high death rate in the crustacean, and the import of green prawns had been banned indefinitely.
Federal Agricultural Minister Barnaby Joyce said at the time of the ban the $358 million a year industry would likely go through a shortage and see prices surge.
The maximum penalty if the suppliers and importers are found to have been illegally importing goods for a commercial advantage under the Biosecurity Act 2015 is 10 years in prison or $360,000 or both.
As the outbreak and companies are still under investigation, the department said it would not be appropriate to comment on whether the act would have been deliberate.
Minister Joyce told ABC's 7.30 the Department of Agriculture was pursuing criminal charges for one importer.
The five contaminated aquaculture farms were undergoing treatment to neutralise the virus and provided no further positive tests were found, the farms would be able to start operation in October 2017.
This was not the first time biosecurity had failed to stop the import of white-spot infected prawns.
In 2011, 20 tonnes of imported green prawns from Malaysia entered the country, 31 per cent of which were infected with the virus.
The explanation given to an estimates hearing was that the quarantine officer had "overlooked" the positive samples.
One of the senators questioning the failure was less polite, Senator Bill Heffernan questioned whether the officer had even read the report or if he had a hangover.
At the time only three of the 20 tonnes were recalled because it was deemed by the department as low risk that the virus would get out.
The low-risk judgment came from the thought that they were intended for consumption and not for bait.
"I caught the guys fishing in the prawn water with prawns they had bought at the supermarket, but you say that will not happen with this - which is a rubbish answer," Senator Heffernan said in reply to the judgment.
That had been the case in the 2016-17 outbreak, when local fishers on the Logan River had been found to be using as bait prawns intended for consumption.
Biosecurity Queensland on Friday started the next stage of its response to the disease, releasing the treated water and introducing a second chlorine treatment into the infected ponds.
Native crustaceans including 110 red-fingered marsh crabs near the premises have been tested, all of which have tested negative.
The Logan River remains under a movement control order, halting the movement of all crustaceans.
As of Friday no one had been found to breach the order.
