Marine heatwave behind South Australia fish kills
Since mid-March, mass fish kills have been reported along the Fleurieu Peninsula and Limestone Coast, South Australia, with affected species including mulloway, rock cod, octopus, and iconic reef fish like leafy sea dragons and blue devils.
The recent Fleurieu fish kill has been linked to a microalgae bloom of Karenia mikimotoi — a species known to be toxic to marine life and can cause respiratory and skin irritation in humans. According to the Environment Protection Authority (EPA), the bloom can be attributed to a marine heatwave, combined with calm prevailing weather.
“The event has been driven by an ongoing marine heatwave, with water temperatures currently 2.5°C warmer than usual, as well as relatively calm marine conditions with little wind and small swell,” said the EPA in a recent media release.
While it’s a confronting sight, it doesn’t have to be for nothing. OzFish is calling on recreational fishers and community members to step up as “citizen scientists” and help document the event. By gathering and sharing data on the affected species, locals can help build a valuable record that will inform future research and responses.
Brad Martin, OzFish’s South Australia Program Manager, says public participation is crucial:
“While it’s great to see community awareness around the fish kills on social media and in the rec fisher Facebook groups, we really need to document when and where these events occur, and the impacted species. Unless, the photos are recorded on a publicly accessible database like iNaturalist or the Atlas of Living Australia, it can be challenging to look back to understand these fish kills. We need that fisher science information to be accessible to researchers and conservation groups long-term.”
Marine heatwave conditions could lead to similar events across different parts of South Australia’s coastal waters. To understand the scale and species impacted in South Australia, we encourage OzFishers to:
- Take photos – Capture images of affected marine life, especially different species.
- Record location, date, and time – GPS coordinates are ideal, but any location details help.
- Upload your observations – use platforms like iNaturalist or the Atlas of Living Australia. iNaturalist records are automatically uploaded to the national biodiversity database.
- Share your data – email your photos to OzFish via info@ozfish.org.au with details of the date, time, and location.
- Spread the word – let others know how they can help and encourage them to report newly impacted areas to PIRSA via FishWatch at 1800 065 522.
These recent fish kills differ from those on the Mid North Coast of NSW, where blackwater events caused by heavy rainfall from Cyclone Alfred are leading to widespread fish deaths.
Regardless of the cause, fishers can make a difference by working together as citizen scientists – turning a difficult situation into an opportunity to learn and protect fish populations for the future.
Join OzFish as a member and help protect the future of fishing.