Tasmania's salmon industry faces scrutiny over mass mortality event, revealing a series of critical failures.
Last summer's mass mortality event in Tasmania's salmon industry was a devastating occurrence, with an estimated 10 tonnes of salmon dying in pens in south-east Tasmanian waters from January to April. The bacterial disease, P.salmonis rickettsia, caused the deaths, leading to a significant environmental impact as dead fish washed up on beaches.
The Environment Protection Authority (EPA) has released a debrief, highlighting several issues that contributed to the crisis. One of the key findings was the lack of accurate and timely information from the industry, which delayed crucial decision-making. The debrief noted that the salmon industry's engagement with regulators was inadequate, and there was no 'mass mortality response plan' in place.
The absence of a response plan, coupled with a perceived lack of accurate advice from the industry, led to communication and coordination challenges. Government agencies reported difficulties in obtaining precise and timely information about the event's scale and duration, resulting in a gap in coordinated public messaging and a loss of community trust.
The debrief also addressed the industry's vulnerability to environmental volatility and emerging marine disease threats. It emphasized that 'business as usual' approaches would not suffice to mitigate these risks. P.salmonis has been present in Tasmania's waters since at least 2021, and salmon have been susceptible to similar bacterial organisms for over two decades.
The disease thrives in seawater temperatures between 12 and 18 degrees Celsius and cannot survive above 25 degrees Celsius. It is now considered endemic in Tasmania's southern and eastern waters.
The EPA's debrief outlined 10 key actions, including the establishment of a marine heatwave response plan, the consideration of an industry code of practice, and the review of information reporting regulations. These actions aim to enhance the industry's preparedness and response to future events.
However, disagreements between the government and the industry emerged in the aftermath. The industry deemed the government's initial response 'overly regulatory' and expressed concerns about potential further regulations. In contrast, government agencies believed that existing frameworks were insufficient.
The industry's sensitivity to right-to-information (RTI) requests also impacted its internal candour during the response. The debrief revealed a lack of a clear control hierarchy, with diverging assumptions about authority, trust, and purpose between the government and the industry during significant events.
An RTI document revealed a concerning trend in mortality rates. In 2025, a Huon Aquaculture pen in the D'Entrecasteaux Channel experienced a rolling seven-day average mortality rate of 0.2%, four times higher than in 2024, but still below the reporting threshold. P.salmonis was responsible for 60% of these mortalities, compared to the usual 20%.
Stocking densities in the most affected pens were at or below 9.3 kilograms per cubic meter, which is below the regulated threshold, according to data from one company. However, the debrief noted that salmon may crowd at preferred depths, increasing the risk of P.salmonis spread, but it did not consider stocking densities as a primary factor in disease spread.
The industry is awaiting federal approval to use the antibiotic florfenicol, which it expects in the coming days. This follows the use of oxytetracycline during last summer's event, described as 'largely ineffective' by Huon Aquaculture. Florfenicol is used in overseas farmed salmon industries, and officials from Chile, where P.salmonis is a known issue, provided valuable advice on vaccinations, selective breeding, antibiotic treatment, and epidemiological surveillance.
The debrief recommended a detailed examination of Chile's regulatory control program for P.salmonis and the ongoing development of vaccines in Tasmania, which offer 15-month protection. However, it also noted that fish immunity diminishes when subjected to repeated stressors in commercial aquaculture settings, such as sea lice infections and harmful algal blooms.
Despite the challenges, the salmon industry is preparing for the upcoming summer, with updates to breeding, feeding, and vaccination practices. However, there is a recognition that no single solution exists, and having a range of tools is essential for effective management.
Independent state MP Peter George, a former anti-salmon farm campaigner, criticized the industry's lack of preparedness, stating that there was no plan to address the event despite its predictability. He expressed concern about the warming waters off eastern Tasmania, which could make the industry increasingly susceptible to mass mortality events.
The government has pledged to conduct a study on the environmental, social, and economic impacts of the salmon industry and to pause its expansion during the study period, aiming to address the industry's vulnerabilities and ensure a more sustainable future.
