The Environment Protection Authority (EPA) has responded openly to questions about salmon farming impacts in Macquarie Harbour and adjacent World Heritage Area (WHA), with statements to the media about how these impacts are monitored and assessed.
In his statements, EPA Director, Mr Wes Ford said that that the EPA uses the visible presence of the bacteria species Beggiatoa, from underwater video footage provided by the salmon companies, as a management control measure in Macquarie Harbour.
"Although this video footage has shown that beggiatoa is present in the WHA, it is in low density and sparsely distributed. This is not evidence that there is a significant environmental impact in the WHA," said Mr Ford.
"I previously commented publicly in February this year that beggiatoa was present in the WHA, and that the continuous mats of beggiatoa observed at the lease boundary closest to the WHA extended for one kilometre in a direction towards the WHA. I also stated that no evidence of direct impact from salmon farming (that is, no fish feed or waste) had been found within the boundary of the WHA," he said.
"The status report for Macquarie Harbour in April 2016, which was released publicly last year, identified that beggiatoa was detected at four sites within the WHA but what wasn’t clear from those detections was whether marine farming had contributed to its presence there.
"On 16 November 2016, I reported on my review of the Spring 2016 compliance monitoring data, which showed a significant visible impact (eg, continuous mats of beggiatoa) at 35 m compliance points at four of the leases in the Harbour (refer: EPA reviews latest monitoring data for salmon farming in Macquarie Harbour).
"As a consequence of this non-compliance, defined by the marine farming licence conditions, I wrote to the companies informing them of the need to take management action to reduce pollution at the lease sites.
"On 30 November 2016, I reported that I had written again to the companies, advising them of my intention to reduce the biomass limit for Macquarie Harbour following my assessment of the latest scientific research provided to me by the Institute of Marine and Antarctic Studies (IMAS), which I promised to publish as soon as this became available as a report (refer: EPA to reduce biomass limit in Macquarie Harbour).
"On 8 February 2016, I published a copy of the Technical Report prepared by IMAS, Environmental Research in Macquarie Harbour - Interim Synopsis of Benthic and Water Column Conditions, January 2017 (refer: Public Release of the Technical Report prepared by IMAS).
"On 24 February 2017, I reported that I had directed Tassal to fully de-stock lease 266, which is the salmon lease situated closest to the WHA boundary showing the most significant impact.
"I published copies of the relevant correspondence between myself and the CEO of Tassal, Mr Mark Ryan, regarding my decision and the timeframe set for de-stocking the lease (refer: EPA directs de-stocking of Macquarie Harbour salmon lease).
"I am now in the process of reviewing the January-February compliance monitoring data provided by the companies along with the benthic surveys conducted by IMAS over the summer season.
"Once I have analysed this information, I will make a further determination regarding the biomass limit for the Harbour, and then inform the companies and the Government regarding my decision.
"On 15 March 2017, Minister Groom advised Parliament that he had sought advice from the EPA regarding impacts on the WHA from salmon farming in Macquarie Harbour, stating that serious environmental impacts inside the WHA were unacceptable.
"I will be providing Minister Groom with a report on what we know about the salmon farming impacts on the WHA as part of the process of determining the biomass limit.
"Beggiatoa is a naturally occurring organism, present in circumstances of low dissolved oxygen where it breaks down decaying plant and animal material. There may be a number of environmental factors which have led to its presence within the WHA boundary. It doesn’t indicate the source of nutrients nor does it provide a complete picture of potential impacts.
"As dissolved oxygen levels recover, the beggiatoa should naturally die off and the marine ecosystem will continue to readjust in response to various environmental factors over time," said Mr Ford.