Fish kills in NSW
Please report any fish death incidents or observations to the Fishers Watch Phoneline on 1800 043 536
What are fish kills?
Fish kills are defined as a sudden mass mortality of wild fish.
Fish kills can occur at any time although data indicates fish kills are more likely to occur in summer or following sudden changes in temperature.
Recent reports of fish kills are included in the table below and we will update the table as we receive reports.
Some of the key causes of fish kills are outlined in the information below.
Blackwater
Blackwater occurs naturally over time when leaf litter and woody debris build up on the floodplain and then get washed into the river system during a flood. It’s an important part of the aquatic food web as it provides food for insects which feed fish, frogs and other aquatic wildlife.
When there is a prolonged dry period, the leaf litter and organic matter on the floodplain builds up until the next flood event. This can result in a significant amount of organic matter returning to the river with any big flushes of water after prolonged drought, making blackwater events more likely.
Hypoxic blackwater
When there is a lot of organic material washed into the river, its rapid decay can consume dissolved oxygen from the water. If dissolved oxygen drops to very low levels, this can cause ‘hypoxic’ water which can be stressful for native fish and can lead to fish kills.
More information on blackwater can be found on the MDBA website , in this factsheet and on the department’s Water website under hypoxic water.
To notify the department of potential blackwater events email water.enquiries@dpie.nsw.gov.au or to report a fish kill, contact Fisheries on the Fishers Watch Phoneline on 1800 043 536.
Bushfire impacts on native fish
Find information on the impacts of bushfires on native fish.
Stratification?
Stratification is when the surface of the water heats up more than the deeper water. That warmer layer tends to be warm and well-oxygenated compared to the deeper water that is colder and oxygen-depleted.
Thermal stratification
Key
- Blue Green Algal Bloom
Algal flourish in warm and still conditions, particularly in the absence of high flow - Surface Water Layer
Warm, high nutrient load from run off.
Dissolved oxygen by day, depletion overnight
Limited fish habitat - Deep Water Layer
Cooler, low light penetration, low dissolved oxygen (hypoxia), Poor fish habitat - Decomposition of organic matter
Depletes dissolved oxygen
De-stratification ("Turn over")
Key
- Sudden weather events or small increases in flow
Can mix the warmer surface water and cooler deep water – essentially breaking down the temperature stratification - These changes can mix the warmer surface water with cooler deep water
Algal blooms may also be disrupted, potentially increasing decomposition (and further depleting oxygen). This means even at the surface dissolved oxygen levels can become critical, killing fish.
Simple things you can do
- Be on the lookout for any changes in water quality - i.e. changes to the colour or odour of your local waterway and report them to us via the Fishers Watch Phoneline on 1800 043 536.
- Contact us on the phoneline if you observe any dead fish or fish starting to gasp at the water surfaces.
Investigating and reporting
Vertessy Report Recommendations – Fish Deaths
2023 Fish deaths in the LDBR: summary of available Fisheries data
Lower Darling-Baaka Recovery Reach Fish Community Monitoring report (August 2023)
- The primary objective of the Lower Darling-Baaka Recovery Reach research was to evaluate the status of the fish community in the LDBR following the 2018 – 19 fish kills and track the trajectory of the fish community, including in Menindee Town Weir Pool and the LDBR downstream of Weir 32.
- Varied responses were observed in species abundances in the study reaches, attributed to the various life-history traits and reproductive strategies of native fish.
- The abundance of some native fish species in the LDBR has declined (in comparison to data collected since 2019) following the fish deaths events of early 2023.
- Murray Cod and Golden Perch abundance has declined in comparison to previous data collected since 2019.
- There were consecutive years of Murray Cod spawning in the LDBR between 2020-2021 on the back of water for the environment delivery.
- Carp were the most abundant species caught during the 2023 sampling.
- The results presented a fish community in continued stress. This is despite earlier demonstrated recovery of native fish from 2020-2022, driven by natural flows and deliveries of water for the environment to the LDBR.
- Sustained and holistic management actions are needed for native fish protection and recovery, with continued monitoring guiding and tracking the effectiveness of these actions in the region.
- With appropriate flow regimes, native fish communities will gradually recover, although catastrophic events such as fish kills related to lack of flow or hypoxic blackwater will hinder, and potentially undermine this recovery. Being long-lived, recovery of local populations of Murray Cod, Golden Perch and Silver Perch will take time.
Lower Darling-Baaka Recovery Reach Fish Community Monitoring report (August 2023)
Recent fish death events
Updated: 25 July 2024, 6.00pm
Below are the fish kills that were investigated and confirmed by NSW Fisheries.
There is a current risk of widespread fish kills across parts of NSW. There may be other fish death events that have not been reported directly to NSW Fisheries. To report fish deaths please contact 1800 043 536. This page will be updated as needed to maintain currency.
1 July 2023 - 30 June 2024
Location and date kill observed | Cause and extent |
|---|---|
Murray-Darling catchments in NSW | |
| Pindari Dam (24 July) | Report of approximately 100 dead fish with a range of species affected including small Murray Cod, Golden Perch and threatened Freshwater Catfish and Silver Perch. The cause has been attributed to increased stress over winter caused by cold-water temperatures, which can impact native fish and water quality. |
| Murrumbidgee River, near Hay (10 July) | Report of approximately 40-50 dead Bony Herring. The cause has been attributed to increased stress over winter caused by cold-water temperatures, which can impact native fish especially Bony Herring who are particularly susceptible. |
| Farmers Creek, Lithgow (3 March) | Report of 10s of dead fish, predominantly Trout. Cause remains unknown. Testing conducted by NSW EPA did not show any elevated results in water quality for factors that may have led to the fish kill. |
| Peel River near the junction of the Peel and Namoi rivers (17 February) | Report of 1000s of dead fish including Murray Cod, Golden Perch, Freshwater Catfish, Bony Herring and Carp. Cause attributed to poor water quality and low Dissolved Oxygen (DO) following high rainfall and fresh event through nearby creeks. |
| Bogan River, Nyngan (12 February) | Report of 1000s of dead Carp. Cause attributed to poor water quality and low Dissolved Oxygen (DO) following breakdown of organic matter. |
| Weir 32 Weir Pool and Lower Darling-Baaka, Menindee (10 February) | A fish death event has been impacting Golden Perch within the Menindee Weir 32 weir pool since 10 February 2024. It is estimated more than 1,000 fish have died during the event. Daily mortalities appear to have peaked during the current incident at around 26 February, with numbers of dead and distressed fish steadily declining since, with minimal observations reported over recent weeks. There have also been reports of fish deaths affecting other species in the Lower Darling-Baaka River including in the Menindee Weir 32 weir pool over this period. Species impacted include Murray Cod, Bony Herring and Carp; however, these have been relatively smaller numbers of fish. Recently DPIRD has completed extensive analysis of affected fish to investigate potential causes of death with the outcomes available in summary here. |
| Murray River, below Hume (31 January) | Report of 10s of dead fish, including Golden Perch and Carp. Cause attributed to impacts from dam infrastructure. |
| Nungar Creek and Tantangara Dam, Murrumbidgee Valley (22 January) | Report of 10s of dead Rainbow Trout and Brown Trout. Cause has been attributed to the combination of algal blooms and extended high temperatures causing a drop in Dissolved Oxygen (DO). |
| Nyngan Town weir pool, Bogan River (15 December) | Report of approximately 200 dead Bony Bream. Cause has been attributed to the combination of algal blooms and extended high temperatures causing a drop in Dissolved Oxygen (DO). |
| Barwon River, downstream of Walgett (13 December) | Reports of dead Carp in the lagoon. Cause has been attributed to the lagoon drying up. |
| Spring Creek Reservoir, Macquarie River near Orange (30 November) | Report of less than a 100 dead Redfin Perch. The Reservoir had just experienced heavy rainfall and the dam was full and overflowing. |
| Lower Darling-Baaka River near Menindee (12 November) | Reports of small numbers of dead Murray Cod and Golden Perch (less than 20). Cause has been attributed to low DO. |
| Wilandra Creek, Murray River (6 November) | Report of hundreds of dead Carp. Cause has been attributed to poor water quality and stranding as water receded. |
| Darling-Baaka River at Menindee Town (3 November) | Report of small numbers (less than 5) dead Murray Cod and Golden Perch in the Menindee Town weir pool. Cause has been attributed to stratification in the town weir pool causing a drop in DO. |
| Darling-Baaka River at Menindee (15-19 October) | Reports of small numbers of dead Murray Cod and Golden Perch. Cause has been attributed to stratification in the town weir pool causing a drop in DO. |
| Darling-Baaka River, downstream of Pamamaroo outlet (25 July) | Report of 10 dead Murray Cod and 1 Golden perch. Cause has been attributed to winter stress due to critically low Dissolved Oxygen (DO) with an associated algal bloom affecting this reach of the river. |
Coastal catchments in NSW | |
| North Creek, Ballina (10 April) | Report received of less than 100 dead fish including Mullet and Bream. Fisheries Officers attended the site and attributed the cause of the event to a drop in Dissolved Oxygen (DO) due to a hypoxic blackwater event due to a breakdown in organic material from localised rainfall. |
| Rocky Mouth Creek, Woodburn (3 April) | Report received of more than 100 dead fish including Mullet, Carp and Herring. Cause has been attributed to a drop in Dissolved Oxygen (DO) due to a hypoxic blackwater event from a breakdown in organic material washed into the creek. |
| Little Lake, Tilba (17 March) | Report of thousands of fish including Bream, Mullet and Eels. Cause has been attributed to a drop in Dissolved Oxygen (DO) due to an algal bloom. |
| Ettalong Creek, Umina Beach (19 February) | Report of 2 dead eels. Cause unknown . |
| Dalhousie Creek, Hungry Head (15 February) | Report of hundreds of dead fish including Mangrove Jacks, Silverbiddy, Flathead and Whiting. Cause has been attributed to low Dissolved Oxygen (DO). |
| Woolgoolga Creek Road (14 February) | Report of less than 50 dead Mullet. Cause unknown. |
| Everlasting Swamp Weir (22 January) | Report of less than 100 dead fish. Cause unknown. |
| North of Yelgun Creek, between Bilinudgel Nature Reserve and South Golden Beach (20 January) | Report of hundreds of dead fish, primarily Bream and Mullet. Cause has been attributed to a drop in Dissolved Oxygen (DO) due to hypoxic blackwater event. |
| Burns Point, Richmond River, Ballina (13 January) | Report of thousands of dead Mullet. Suspect cause has been attributed to a drop in Dissolved Oxygen (DO) due to hypoxic blackwater event. |
| Pearl Beach Lagoon North, Hawkesbury River (26 October) | Report of approximately 50 dead fish. Investigation by local council indicated Dissolved Oxygen (DO) was critically low. Cause has been attributed to low DO. |
| Bunyip Swamp, Clarence River at Trenayr (25 October) | Report of 50 dead Longfin Eels. Cause has been attributed to drying conditions in Bunyip Swamp. |
| Hayes Creek, Sapphire Beach near Coffs Harbour (20 October) | Report of less than a hundred dead Mullet, cause has been attributed to low DO due to an algal bloom and drying conditions. |
| Parrabel Creek, Macleay River – Moparrabah (15 September) | Report of small scale fish kill affecting Catfish and Bass. The cause has been attributed to exacerbating drought conditions mixed with low Dissolved Oxygen (DO). |
| Swan Lake, Cudmirrah (11 September) | Report of dead Eels at the entrance tunnel. Cause unknown. |
| Crookhaven River, Shoalhaven (15 August) | Report of less than 100 dead Carp. Cause unknown. |
| Horsefalls, Hazelbrook Creek(23 August) | Report of hundreds of dead Crayfish. Cause unknown. |
| South Arm Creek, Bowraville (12 August) | Report of approximately 70 Eel-tailed Catfish. Cause unknown. |
