2019 Fish kills

Namoi River (late Nov)

Numerous reports of small fish kills throughout the Lower Namoi, Upper Namoi and Peel reaches.

Suspected cause is drying pools and low water quality due to lack of inflows.

Gwydir River, Roumalla Creek near Kingstown (late Nov)

Small event in an upper tributary of the Gwydir River. Approximately 20 fish including Murray Cod and Freshwater Catfish reported.

Cause was rainfall with approximately 50mm washing loads of organic matter into a pool, causing low dissolved oxygen conditions.

Macquarie River, upstream of Burrendong Dam (late Nov)

Limited information to date of a small fish kill of less than 10 fish.

The cause of the kill is unknown.

Blowering Dam, an isolated bay (late Nov)

Approximately 50 large Murray Cod affected.

NSW DPI Fisheries staff attended the scene and collected fish and water samples for further analysis. Results from the analysis indicate that any potential elements that may cause fish kills were all below detectable levels. Localised fish kills in impoundments after rainfall events are not uncommon. It is likely that rapid drops in temperature at the time of the fish kill may have caused the mixing of water, resulting in poor water quality in the dam that affected a number of fish.

Lower Darling River, downstream of Weir 32 near Moorara, Bald Hill, Tolarno and Karoola (Nov)

Ongoing reports of small numbers of fish dying in isolated pools at locations downstream of Weir 32. Affected fish reported are Murray Cod and European Carp.

Cause of death is due to drying pools and poor water quality from lack of inflows.

Mehi River, downstream of Moree (6 Nov)

Approximately 300-400 dead fish reported consisting of Bony Herring, as well as a small number of Murray Cod, Golden Perch and Carp.

The cause is a flow following extremely dry and warm conditions in the Gwydir valley, with some rivers and creeks near Moree having not flowed for more than 100 days.

A release of water was made on 15 October from Copeton Dam and the front of the flow included a portion of poor quality water, which moved through the system.

The delivery of flows to replenish refuge holes within the Mehi will provide long-term benefits to native fish populations during the current drought period.

Short-term, localised impacts on water quality are expected when flows resume within drying rivers, either through natural rainfall events or controlled releases from dams.

Limited information to date of a small fish kill of less than 10 fish.

The cause is unknown.

Lake Ainsworth, Lennox Head (4 Dec)

Up to 100 Eel-tailed Catfish reported. Water quality sampling did not identify any unusual results.

The cause of the kill is unknown.

Lake Cathie / Innes near Port Macquarie (early to late Nov)

Hundreds of dead and stressed fish reported on a number of occasions. Likely to be a continuous event with numerous during adverse weather conditions.Cause is due to low water levels that have led to high salinity and elevated water temperatures resulting in significant stress being placed on fish and other aquatic organisms. This ongoing stress has resulted in some small scale fish deaths which may continue to occur.

Macleay River, 8km stretch upstream of Kempsey, (Nov-Dec)

Thousands of fish including Australian Bass, Freshwater Mullet and Eel-tailed Catfish reported dead on social media. Investigation unable to occur as located in active fire grounds.

The cause is rainfall in bushfire affected areas creating run-off depositing large amounts of ash and sediment (due to the lack of remaining vegetation) into the river within short periods, resulting in rapid drops in dissolved oxygen.