Tasmania's Salmon Waste Crisis: Regulators Scramble Amidst Fish Die-Off

It was a waste crisis that Tasmania hadn't planned for: too many dead fish.

In early 2025, farmed Atlantic salmon were dying from a bacterial disease at such a high rate that it had exceeded the state's capacity to deal with them.

WARNING: This story contains images of dead animals.

Regulators were having to approve emergency solutions — documents released under right-to-information provisions show — and there was a sense of frustration, including from chief veterinary officer Kevin de Witte:

"I look forward to the day when we can have a government [and] industry discussion exercise on the issue of emergency mortality disposal."

Before that discussion could happen, the waste contractors, local councils and the state's Environment Protection Authority (EPA) had a worsening backlog to deal with.

There was one major problem, however: the EPA was unsure of where all the dead fish — or 'morts' — were ending up.

A broad email was sent out, titled: "Salmon — chasing the trail of mortalities".

"Questions are coming … around exactly where these morts are going," the EPA's environmental regulation director wrote.

"We're starting to try to get a feel for where all these mortalities have gone, and where there are gaps."

Some of these "gaps" were identified over the course of the next few weeks, including pressure on processors, compliance issues, and how some fish were being "disposed of".

'Lumpy' landspreading a sign of pressure

More than 3,000 tonnes of salmon died at salmon producer Huon's sites in one month during the mass mortality event.

Almost three-quarters of this was processed through an ensiler — machinery that breaks fish down — to create material for landspreading at several properties near Oatlands in the state's midlands, a form of fertiliser intended to improve farm yields.

Keeping track of this largely fell to Southern Midlands Council environmental manager Grant Finn, who estimated that about three months' worth of fish was processed in just two weeks.

During his checks, he noticed the material was being spread on a new piece of land, writing:

"The odour is something else."

It was deemed to be unauthorised, and the operator — Spectran — was later fined $2,020.

"The … material was sourced from another facility, so, in short, it wasn't Spectran's own," Mr Finn said.

"The particle size was significantly larger than what had previously been received, which indicates a shortened process given their increased mortality rates."

Mr Finn visited the site with the EPA and Biosecurity Tasmania, finding multiple issues.

An EPA file note stated that the material was spread within metres of a temporary watercourse.

"The lumpiness of the landspreading material may reflect that the ensiler is not processing the fish waste sufficiently," it reads.

"It is preferable that the ensiler processes the fish in four hours. However, due to pressures of the fish kills, they had reduced this to two hours."

There were other concerns, including a fish pit with "spillage along the edge".

A Spectran spokesperson said improvements to processes have since been made, and the company was having to handle a significant amount of waste during the period.

Guidelines for salmon material lacking

The issue at the property pointed to a larger issue facing councils and regulators, according to Southern Midlands mayor Edwin Batt.

He said that, unlike other forms of waste, there are no set guidelines for landspreading fish material.

"You'd get a better outcome if there was an approved management monitoring of this, which mapped out precisely what the requirements were and applied some science around those requirements," Cr Batt said.

Landspreading has increasingly become the chosen method to respond to seasonal mortality peaks, as a method of replacing the use of synthetic fertiliser.

The council is satisfied with how third parties, such as Spectran, are responding to the demand, and that issues from the mass mortality have been dealt with.

But Cr Batt said there were concerns that salmon companies were shifting the risk.

An EPA spokesperson said they are working with councils to support them in regulating landspreading.

Spectran said it had developed its own guidelines in consultation with the EPA, councils and Biosecurity Tasmania, similar to guidelines for biosolids.

The company landspread 16,200 tonnes of material during the mortality event, up from its average of 7,200 tonnes.

Shallow burials to clear 'backlog'

By the end of February 2025, salmon producer Tassal's processes appeared to have reached capacity.

Its rendering site at Triabunna had been processing 90 tonnes of dead fish per day, attempting to generate reusable products.

The ensiler was no longer operating because there were not enough tanker trucks to transport it.

Landfill at Copping, east of Hobart, could take no more because the trench was "full", EPA documents show, and 315 tonnes of dead fish went to landfill.

Tassal contacted the EPA for approval for several shallow burials of the fish on fields near Sorell. It involved digging a shallow trench, laying down sawdust, then the fish and then woodchips.

"These shallow burial properties could cover their 250 tonne backlog," an EPA email reads.

That appeared to ease the immediate pressure, but in another part of the state, the use of a shallow burial for Huon's waste was heavily questioned.

Odour made neighbour's property 'unliveable'

The EPA visited a property near Ouse in the central highlands in late March, where 491 tonnes of Huon salmon had been placed in shallow burials.

They struggled to find approvals and described an earlier environmental protection notice as "very badly written".

There were other issues, as discussed in an EPA file note.

"At the first mount an odour was detected approximately five metres from the mound," it said.

Despite this, the EPA later said that "100 per cent of salmon mortality waste [was] beneficially reused" for March 2025.

That statement has since been removed from the EPA website.

The shallow burial had also resulted in a complaint from the neighbour.

"There were offensive odours for at least two weeks that made their house unliveable," an EPA note reads.

"Burial that has occurred on the northern slope has a high potential to cause runoff to waterways that feed his farm.

"No one contacted him prior to disposal, as required in the environment protection notice."

The use of shallow burial has almost entirely ceased in Tasmania.

More processing capacity, but more deaths likely

In assessing the mass mortality event, the EPA found that the scale of the deaths had exceeded Tasmania's mortality retrieval systems.

About 5 per cent of the mortality waste went to landfill.

The three major salmon producers — Huon, Tassal and Petuna — were required to write new waste management plans.

Huon's plan points out that the Tassal rendering site at Triabunna remains the first destination, but that it has "limited capacity".

After that, it must ensile its own dead fish material to then be spread at several properties in the midlands and highlands.

Expanding the composting facility at Copping was also identified as a solution.

Huon is spending $2.1 million to improve its ensilage capacity and to have additional tanker capacity.

It has the capacity to handle a scenario where 50 per cent of its fish in a lease die over an eight-week period.

But it has modelled worse potential disease outbreaks — such as infectious salmon anaemia virus — which would see a significantly larger amount of fish die compared with the recent bacterial disease, again overwhelming the waste system.

More mass mortalities could occur

The documents were obtained by the Bob Brown Foundation (BBF) under right-to-information legislation.

BBF marine campaigner Alistair Allan said the lack of planning for the mass mortality was concerning.

"You have senior members of the government saying, 'we wish we had a plan with how to deal with this properly',"

"All evidence suggests it will happen again.