Fish kill between Newcastle and Redhead in November 2022 investigation findings
The NSW EPA, Department of Primary Industries (Fisheries) and Department of Planning and Environment have completed a multi-agency investigation into the unusual oceanic fish kill that occurred between Newcastle and Redhead beaches in November last year.
Fish were impacted at Newcastle, Merewether, Dudley and Redhead beaches.
Investigations included possible pollution sources, fish and water samples with assessments of physicochemical parameters, nutrients, algae and algal toxins. We also looked for evidence of an upwelling event.
The investigation found:
- The impacted fish species were non-commercial plankton eating fish normally found in inshore reefs at depth.
- No land-based pollution incidents or activities could be attributed to the cause of the fish kill.
- Water testing found elevated levels of nutrients significantly exceeding Australian and New Zealand Environment and Conservation Council (ANZECC) guidelines for the protection of marine waters.
- Chlorophyll-a in waters at depth was elevated, indicating the likely presence of high algal numbers.
- Dissolved oxygen was found to be low for the waters at depth.
- There was evidence of a natural “upwelling event” at the time of the fish kill, which can cause high nutrient loads in the water and lead to algal blooms.
The investigation found the likely cause of the fish kill was a natural event due to a nutrient induced algal bloom and low dissolved oxygen conditions.