Macquarie Harbour is one of Tasmania's most extraordinary marine environments — vast, remote, deep and dark. It is also the home of Tasmania's salmon farming industry, and for more than three decades the two have shared these waters. Unique harbour geography, with a natural layer boundary known as the halocline, limits the mixing of oxygen-rich surface water into the depths and also prevents oceanic waters flowing into the unique system.
The industry has responded by taking on the active role of supplementing dissolved oxygen in those deep waters — and that commitment is now entering a major new phase.
The Macquarie Harbour Oxygenation Project (MHOP) proved that mechanical injection of oxygen into the Harbour's deep waters measurably improves conditions for seafloor ecosystems, including the habitat of the Maugean skate — an ancient species found on the West Coast of Tasmania.
Following two successful trial phases (MHOP & MHOP1.5), Salmon Tasmania and its members — Tassal Group, Huon Aquaculture and Petuna Aquaculture — have now formalised the next step.
The Oxygenation Offset Program in Macquarie Harbour (OOPMH) is a fully funded, large-scale operation about to commence, backed by a project agreement with the Fisheries Research and Development Corporation (FRDC) and the Australian Government's Department of Climate Change, Energy, the Environment and Water. (DCCEEW). The work starts now.
The OOPMH has four goals. First, to fully offset the oxygen demand below the halocline attributable to salmon farming through mechanical oxygenation — a genuine, measurable contribution. Second, to develop a validated and scalable methodology for long-term oxygen delivery that can be sustained indefinitely. Third, to actively support the health of benthic ecosystems and the habitat of species like the Maugean skate, going beyond compliance to make a positive ecological contribution. Fourth — and most forward-looking — to transition full operational responsibility for oxygenation to the industry itself once the program has been validated.
By the time the OOPMH reaches full capacity, it will be capable of delivering up to 18 tonnes of dissolved oxygen per day into Macquarie Harbour. The current design is for three purpose-built modular barges deployed across the Harbour, each self-contained with its own power and oxygen generation equipment. Oxygen is extracted from ambient air using proven industrial technology then pumped to depths of 20–35 metres where fine-dispersion nozzles ensure efficient transfer into the water column. Harbour currents carry dissolved oxygen widely, making fixed-location systems more energy effective.
The operational base is the industry's THub facility near Strahan — providing fuel storage, vessel access, maintenance capability and remote monitoring infrastructure, well away from township and public wharf activity.
The combined workforce of the three partner companies exceeds 120 people with deep expertise in remote marine operations, engineering, and environmental management.
Salmon Tasmania's existing solar-powered sensor network continuously monitors dissolved oxygen, temperature, and salinity across the harbour in real time, with data shared with IMAS, CSIRO, and the EPA.
This feeds directly into an adaptive management framework - when natural ocean water brings oxygen-rich water into the harbour, systems can be throttled back; when deep water conditions require greater output, the response is immediate. A parallel FRDC science program (Project 2025-038) tracks ecological response and guides operational decisions.
The industry drives the operational aspects of the program and the IMAS and CSIRO science directs it with regulatory (State and Federal) oversite.
The program carries an explicit commitment to reducing its carbon footprint. Current diesel-powered barges represent the reliable foundation, but the project team is already developing pathways for shore-based electricity generation and subsea oxygen delivery pipelines that if feasible could cut diesel consumption significantly.
At-depth injection systems that further reduce pumping energy are also being evaluated. The goal is an oxygenation system that is not just effective, but efficient and sustainable for the long term.
Salmon Tasmania recognises that Macquarie Harbour belongs to the broader West Coast community. Community engagement continues through the Strahan Community Forum, NRM Cradle Coast, ongoing collaboration with various Aboriginal Corporations, regulators and The Maugean Skate National Recovery Team.
By mid-late 2027 it is forecasted the OOPMH will have generated a full year of large-scale operational data, documented measurable improvements in deep water oxygen conditions, and established the systems, knowledge base and confidence for the industry to operate oxygenation as required in the Harbour.
Detailed reporting will capture everything from barge and system performance to innovation trials and operational learnings — a resource for aquaculture management well beyond Macquarie Harbour.
For the Maugean skate and the wider benthic ecosystem, the measure of success is straightforward: consistently improved dissolved oxygen in the deep waters they call home, maintained by an industry that has chosen to be part of the solution.
It is expected that as the oxygen drawdown from the Salmon industry is offset that other industries will be able to modify how they operate and use the Harbour to maximise the oxygen supply and habitat to this unique system.
Science is already looking at this and there are also a range of other research avenues being planned to look at other aspects like the role of metals from legacy mining pollution play, invasive species, shifting dynamics of potential predators and prey of the skate and the role that climate change might be playing in oxygen dynamics in the Harbour.
The Oxygenation Offset Program in Macquarie Harbour (OOPMH) — FRDC Project 2025-041 — is supported by funding from the FRDC on behalf of the Australian Government.
In response to concerns about the Skate, in June, a triumvirate of Activist Non-Government Organisations, the Bob Brown Foundation, Australia Institute, and Environmental Defenders Office requested the federal government “reconsider” a 2012 decision to approve salmon farming in Macquarie Harbour as a ‘Non-Controlled Action’ under the Environment Protection and Biodiversity Conservation Act (EPBC).
Federal Environment Minister Tanya Plibersek has now initiated a formal, legal review of the industry’s approvals under Australian Government environmental law, and has opened consultation to all stakeholders and the public.
At the end of this review, the Minister could reverse the Australian Government’s 2012 decision and decide Aquaculture in Macquarie Harbour should now be a ‘Controlled Action’.
This means the industry will need to apply for new approvals from the Australian Government to operate as a Controlled Action.
The problem is it could take two years to gain these approvals and it would be technically illegal under Australian law for the industry to operate in the harbour in the meantime.
The industry would need to ‘down tools’ and exit the harbour as soon as practical with animal welfare considerations. This will see jobs lost and massive disruption for our workers in Strahan, and right across Tasmania. It is very difficult to see the industry ever resuming in the harbour.