A significant harmful algal bloom, dominated by the species Karenia mikimotoi, has been impacting large areas of South Australia’s coastline since March 2025. The naturally occurring algal bloom has caused widespread marine mortalities, disrupting current fishing activities and raising questions on the impact of the mortalities on the stocks.
Overview:
A marine heatwave (MHW) has been affecting southern Australia since September 2024. Like heatwaves on land, MHWs are periods of exceptionally warm ocean temperatures. These elevated temperatures are considered to be a contributing factor to the harmful algal bloom (HAB).
This is a dynamic situation as the bloom travels depending on weather and water conditions and the impacts in these areas can therefore be unpredictable.
The last time a large event of this type of algae was recorded in SA was in 2014 in Coffin Bay. Similar outbreaks around the world have generally lasted between a week to several months depending on wind, rain and ocean temperature fluctuations.
While there is no way to dilute or dissipate the current bloom, Government agencies are working together to monitor the situation, collect and analyse samples across various locations, and ensure the community has access to up-to-date information about environmental, primary production, and public health impacts. Importantly, the scientific monitoring and modelling currently undertaken by SARDI plays a critical role in understanding the drivers of such events. This research will support the development of predictive tools and management strategies that can help detect, prepare for, and respond to similar occurrences in the future.
Impact on fish stocks:
Fish stocks in South Australia are closely monitored and assessed regularly, and the vast majority of South Australian fish stocks are reported to be in a healthy state, with fishing levels managed sustainably. PIRSA will continue to monitor fish stocks to ensure management arrangements are adequately protecting our important aquatic resources and will consider any advice from SARDI about the impact of algal blooms on stocks in setting appropriate management arrangements into the future.
While marine mortalities have been observed in multiple locations, many affected species are highly mobile and may have moved out of the impacted area. Monitoring of fish stocks and environmental conditions will continue to help understand the full extent of the impact.
State Government support package:
The State Government’s Emergency Management Committee of Cabinet has approved a $28 million harmful algal bloom support package towards industry support, science and research, communications, community support and clean up.
The State Government will contribute $14 million, matching the Commonwealth’s contribution, with elements of the package to begin rolling out immediately.
The support package has been devised with key stakeholders, industry and communities to provide the most effective and immediate relief. Some of the key measures of the package include:
- a coastal monitoring network
- a new national testing laboratory for brevetoxin/biotoxin testing in SA
- public forums for impacted coastal communities
- public information campaigns aimed at rebuilding confidence and encourage visitors to coastal regions and marine based tourism businesses, promotion of the seafood industry and the benefits of recreational fishing
- community fund to support activities and small projects in affected communities
- beach clean-up funding for local government
- $10,000 Small Business Support Grants for eligible small businesses.
These measures are in addition to the fee relief previously announced and the $1,500 direct support payments to impacted primary producers.
What you can do:
You can still enjoy recreational fishing in South Australia!
Seafood such as fish, crabs, prawns, and lobsters caught live are safe to eat provided they are properly cleaned, and the viscera/digestive tracts are removed prior to cooking and eating. Seafood from retail outlets is safe to eat too as rigorous testing is undertaken. However, SA Health does not recommend people eat fish or cockles found dead because of likely spoilage and decomposition.
Report any marine mortalities to Fishwatch on 1800 065 522, so they can be added to the testing regime being carried out by PIRSA.
We encourage anyone who discovers dead or sick marine wildlife to contact their local National Parks and Wildlife Service office.
Keep updated by visiting Harmful algal bloom (HAB) situation update – Department of Primary Industries and Regions South Australia – PIRSA
To further support the public in getting relevant and timely information, a primary information hub is also available at www.sa.gov.au/algalbloom