Maximum Permissible Biomass
The Director, EPA has replaced the standing biomass determinations that were made by the Secretary, Department of Natural Resources and Environment Tasmania and the Director, EPA, for Macquarie Harbour. Commencing 1 September 2022, the Director, EPA has introduced a more accountable system for limiting the production of finfish in Macquarie Harbour. This determination specifies the harbour wide Total Permissible Dissolved Nitrogen Output (TPDNO), providing each company growing finfish in Macquarie Harbour with a share (apportionment) of the total TPDNO. The aim of this TPDNO determination is to build upon improvements in ecosystem function and dissolved oxygen levels that have been observed in Macquarie Harbour since 2017.
The rationale for changing from biomass limits to a TPDNO can be found here Rationale for changing management determination.
A statement of reasons supporting the Director, EPA’s decision for moving towards a TPDNO can be found here Statement of Reasons for TPDNO.
|Date of Determination||Tassal||Huon||Petuna|
|1 June 2018 - 31 May 2020||10.26||10.26||10.26|
|1 June 2020 to 31 May 2022||10.26||10.26||10.26|
|1 June 2017 - 31 May 2018||13.0 (28.0 with implementation of a waste capture system approved by the Director, EPA)||13.0 (without approved waste capture system)||13.0 (without approved waste capture system)|
|14 February - 30 April 2017||25.35||12.56||9.65|
Total Permissible Dissolved Nitrogen Output (TPDNO)
Aquaculture, like most farming practices, may impact the environment through the introduction of nutrients into the environment. Nitrogen can have a big impact on coastal marine systems. Excess nitrogen enters the environment from excess fish feed, fish faeces and urine.
One way to regulate the nitrogen from salmon farming, is for the EPA to impose a Total Permissible Dissolved Nitrogen Output (TPDNO). This restricts how much dissolved nitrogen companies are allowed to release into the environment in any 12 month period. Companies must not exceed the TPDNO.
Salmon companies operating in the D’Entrecasteaux Channel and Huon River MFDP area, the Macquarie Harbour MFDP area and the Tamar Estuary MFDP area, must comply with a TPDNO (tonnes of nitrogen emitted per rolling 12 month period).
|Date effective from||Tassal||Huon||Petuna|
|1 Sept 2022 - 31 Aug 2027||151.2||124.2||224.7|
Environmental licences require companies to undertake regular visual monitoring of the seabed to detect environmental changes associated with farming salmon. This occurs at all salmon farming sites across Tasmania.
One requirement is that there must be no significant visual impacts at, or past, 35 metres from the lease area. Visual impacts are monitored by remotely operated vehicles fitted with high definition cameras. Visual monitoring occurs at compliance points located around the lease area. Where significant impacts are detected, additional monitoring surveys are conducted at points further away to assess impact.
If a significant impact is detected within or outside the lease areas, the EPA may require management responses as well as further investigation.
Data is required to be collected annually, however the timing of environmental surveys is lease dependant and can take place within any month throughout the year.
Data from the current monitoring period
Quarter 2, 2023
|Company||Lease number||Number of 35m compliance points surveyed||Number of compliant 35m compliance points surveyed|