'Critical habitat' decision could affect Macquarie Harbour salmon farms

Tasmania's environment department is considering declaring Macquarie Harbour a "critical habitat" for the endangered Maugean skate, which could have significant ramifications for the salmon industry on the state's west coast.

If approved, it would be the first time a critical habitat has been designated since the Threatened Species Protection Act came into force three decades ago.

It would require a management plan to be developed for the purpose of protecting the prehistoric ray species, which is found only in Macquarie Harbour.

The same waterway is used by three major aquaculture companies to produce thousands of tonnes of farmed salmon each year.

Details of the critical habitat consideration were revealed in Right to Information (RTI) documents released by the Department of Natural Resources and Environment.

The documents show the Scientific Advisory Committee (SAC) wrote to the department in April to say it had received advice from four independent experts who agreed:

• Macquarie Harbour is "critical" to the Maugean skate's survival and recovery.
• There are multiple interacting threats, "including declining dissolved oxygen, aquaculture impacts and climate influences that pose a high risk".
• The threats "at least in part, [are] manageable through targeted human intervention at the scale of the harbour".

On that basis, the SAC concluded:

"Macquarie Harbour meets the criteria for designation as a critical habitat for the Maugean skate."

Under the act, the decision on whether to declare the harbour as a critical habitat now rests with the department's secretary, Jason Jacobi.

In August, Mr Jacobi agreed to a $12,800 funding request for the SAC to get additional independent advice to develop the geographical boundaries for a potential declaration.

"I agree that further scientific advice on spatial delineation is the next important step … to assist SAC in evaluating a range of scientifically defensible boundary options for habitat(s), including consideration of the smallest ecologically meaningful area through to broader, practical boundary configurations where supported by evidence."

Declaration would require management plan

If a critical habitat declaration is made, a management plan would then need to be developed in consultation with affected landowners and leaseholders within 90 days.

Jan McDonald, an environmental law expert at the University of Tasmania, said this could include "additional controls" on salmon farms.

"The land management plan could potentially require significant destocking and potentially the cessation of salmon aquaculture in Macquarie Harbour," Dr McDonald said.

"That really remains to be seen.

"We don't know yet what the scope of the spatial designation will be and what is ultimately indicated as necessary for the purposes of conservation and management."

Dr McDonald said a critical habitat declaration could also trigger a requirement for the government to pay compensation to affected parties.

Environment group says entire harbour should be declared critical habitat

Environment Tasmania, which has been campaigning with the Environmental Defenders Office on the issue, said all of Macquarie Harbour, not just a section of it, should be declared a critical habitat.

"[The Maugean skate is] not going to respect delineation that is set by bureaucrats," Environment Tasmania's Jess Coughlan said.

"The entire harbour, including the area of the Tasmanian Wilderness World Heritage Area and the areas occupied by salmon farms, are the only habitat on earth where this species exists.

"Therefore, this environment, the entirety of the harbour, is critical to its survival and the entire harbour should be listed as critical habitat."

Independent MP Peter George, who submitted the RTI request, said a designation would help protect the species.

"And if this means reducing or eliminating salmon farming, which is by far the biggest problem in that harbour, then so be it, because it is certainly of national and international importance that we look after the Maugean skate," Mr George said.

Tasmanian Greens deputy leader Vica Bayley said the declaration needed to be made urgently.

"We're getting into an El Niño summer where we know there's going to be marine heat wave situations and terrestrial heat wave situations," Mr Bayley said.

"And it's a significant problem, and we can't afford for the skate to suffer another long hot summer subject to the impacts of aquaculture."

Industry says it can coexist with Maugean skate

Salmon Tasmania did not respond directly to questions about whether it supported or opposed a potential critical habitat declaration.

But in a statement, a spokesperson said: "The salmon industry actively supports efforts to ensure the Maugean skate's long-term survival in Macquarie Harbour, contributing to both ongoing research and the oxygenation program to inform our management practices.

"The evidence shows that aquaculture coexists with the Maugean skate in the Harbour and production levels have significantly reduced as part of responsible adaptive management."

In a statement, the department said it was committed to supporting science-based conservation of the Maugean skate.

"NRE Tas is not in a position to comment on the timing of any decision, the potential extent of any area that may be considered, or any implications for particular industries, activities, approvals or licences.

"Any consideration of a declaration would be subject to a consultation process that takes on board the views of all affected stakeholders."

It also said recent monitoring results had shown "encouraging signs" for the Maugean skate population and environmental conditions in Macquarie Harbour.

Maugean skate numbers fell by almost 50 per cent between 2014 and 2021 due to reduced oxygen levels, which coincided with a substantial increase in salmon farming.

The dramatic decline prompted environmental groups to seek a review of the federal government's 2012 approval of the expansion of salmon farming in Macquarie Harbour.

But before the federal election last year, parliament passed an amendment barring reconsideration of approvals for industries that have operated for more than five years.

Earlier this year, the federal environment minister decided not to "uplist" the Maugean skate from endangered to critically endangered, based on advice from the independent Threatened Species Scientific Committee.

Several skates were released into the harbour in June as part of a captive breeding program designed to protect the species.