The Director of the Environment Protection Authority (EPA) has written to salmon lease holders in Macquarie Harbour advising them of his intention to reduce the biomass limit following an assessment of the most recently available scientific data.
The decision by EPA Director Wes Ford follows consideration of the current dissolved oxygen levels in the deeper waters of Macquarie Harbour, and the extent of the presence of Beggiatoa species in the harbour over the past six months.
Mr Ford said the levels of dissolved oxygen in the deeper waters are likely to be contributing to the distribution of Beggiatoa and a change to the in-fauna ecology in the vicinity of the leases.
"In the last few weeks I have received the findings of scientific information from the Institute of Marine and Antarctic Studies (IMAS) and have reviewed this information on a lease-by-lease basis in my considerations of the proposed biomass limit," Mr Ford said.
"As a result, I have determined that the biomass needs to lowered and a new limit needs to be set."
"I have advised the companies of my intention to reduce the biomass in the harbour over the summer and that the biomass for the next two years will be set at a lower limit."
Mr Ford said his decision making and management system is made with regard to the objectives of the Marine Farming Planning Act 1995 and the Resources Management Planning System of Tasmania.
"My proposed decision takes into account the environmental, social and economic impacts associated with setting a sustainable management system for the harbour," Mr Ford said.
"It is important to remember that this is a limit - not a target. There are also mechanisms in place to further reduce the limit if conditions in the harbour deteriorate into the future."
Mr Ford said he has written to the companies explaining his proposed determination and they have been given four weeks to consider the direction and provide him with their forward planning intentions.