Fish kills

Darling River, Menindee (28 Jan)
Affecting approximately 30km of the Darling River from Weir 32 to Menindee main weir and upstream.

Darling River, Menindee (6 Jan)

Affecting approximately 45 km of the Darling River below the Menindee Main Weir including Menindee township

• Both are suspected to be caused by very low dissolved oxygen levels triggered by sudden drops in temperature that disrupted existing algal blooms with mixing of  low dissolved oxygen water through the water column
• Hundreds of thousands of fish affected of a range of species on both occasions. Fish affected include significant numbers of Bony Herring (Bream), Golden and Silver Perch, Murray Cod and Carp.

• One Murray Cod confirmed dead on 18 Jan, and further reports of fish deaths along a 500m section of the lake on the morning of Jan 21.
• Thousands of small fish observed on 21 Jan including Gudgeon spp, Murray Cod, Golden Perch, Freshwater Catfish, Carp and shrimp.
• Further fish kills occurred in the Lake and upstream and downstream on Jan 22.
• Up to 100 dead fish were reported from an isolated pool immediately downstream of Lake Inverell on 30 Jan. Species included Golden Perch, Murray Cod, Eel-tailed Catfish and Carp
• Suspected cause is low dissolved oxygen and deteriorating water quality

Lake Keepit (Namoi River) (9, 22, 24 and 30 Jan)

• Low dissolved oxygen as lake level dropped and hot weather
• Hundreds of Murray Cod and Golden Perch affected

Lake Burrendong (Macquarie River) foreshore (12 Jan)

• Recent localised storm activity that produced a flow event that contributed organic debris into the lake resulting in a sudden reduction in dissolved oxygen levels when the organic debris started to decompose
• Over one thousand fish observed namely Carp and Redfin Perch with small numbers of native fish

• Water quality in all weir pools is deteriorating with low dissolved oxygen levels
• Small numbers of dead fish (<10) observed in Redbank Weir before Christmas 2018 and in the Balranald Weir Pool on 9 Jan
• Thousands of fish observed on 31 Jan including Murray Cod, Golden Perch, Silver Perch, Bony Herring (Bream) and Carp.
• Suspected cause is very low dissolved oxygen levels triggered by a sudden drop in temperature that mixed low dissolved oxygen water through the water column.

• Approximately 20 Trout (Rainbow and Brown Trout) reported dead. Cause is suspected to be high water temperatures as dissolved ovygen levels were within normal ranges (6.9mg/L) and no other factors were observed/reported.

• Less than 50 fish observed dead including  Golden Perch and Murray Cod.
• Suspected cause is low dissolved oxygen and water stratification

• Approximately 70 fish (mostly Mullet). The cause is suspected to be low dissolved oxygen levels due to minimal river flows at the site and high temperatures.

• Hundreds of Bully Mullet and small numbers of Mangrove Jack observed dead at these locations.
• Cause is suspected to be very low levels of dissolved oxygen, shallow water levels and high temperatures

Lake Cathie / Innes near Port Macquarie (8 Jan)

• Deaths suspected to be caused by low levels of dissolved oxygen from high water temperatures and low lake water levels with no flushing
• Hundreds of fish reported including Bream, Tarwhine and Whiting

• Approximately 25 fish were recorded dead, including Herring and Moses Perch. All fish were less than 15cm in length. Small numbers of deceased marine worms were also observed.
• The cause was marine algae that washed into the harbour and subsequent low dissolved oxygen caused by the decomposing algae. The kill is likely to be a result of changing currents and tides causing significant amounts of the algae to be washed into Crowdy Head Harbour and trapping fish before they could escape.
• The major species was Ceramium along with a diatom species. Ceramium can bloom in summer due to elevated nutrients associated with cold upwellings that naturally occur due to do the activities of the East Australian Current and North East winds.

• 17 mullet and 1 shortfin eel were observed dead on 21 Jan with the deaths estimated to have occurred between 5-7 days prior.
• Bellambi Lagoon is an intermittently opening coastal lagoon.  The cause is estimated to be rainfall during 9-12 January resulting in a natural opening of the entrance of the lagoon.  Local residents report a significant lowering of the lagoon water level following the opening which may have stranded some fish.