Fish kills in NSW

Recent fish kills reported in NSW due to environmental conditions

Fish kills are defined as a sudden mass mortality of wild fish. In NSW we are likely to see further severe fish kills across coastal and inland catchments during the summer of 2019/20. Recent reports are included in the table below, and will continue to be updated over the summer.

Fish kills can occur at any time although data indicates fish kills are more likely to occur in summer or following sudden changes in daily temperature.The prolonged dry conditions being experienced across NSW, coupled with long range forecasts from the Bureau of Meteorology indicate these conditions will continue throughout the summer.

This is impacting both inland and coastal waterways with significant concerns held for the catchments in the northern Basin, including the Border Rivers, Gwydir, Namoi, Macquarie and Barwon-Darling, as well as the Lower Darling and Lachlan catchments.

The extensive bushfires across NSW present an additional risk for native fish populations in both coastal and inland catchments. Fish can be directly impacted during fires through extreme high temperatures, loss of habitat, or be threatened from rapid declines in water quality if rainfall occurs in recently burnt areas. Run-off from rainfall events can wash large amounts of ash and sediment into rivers following fires, causing rapid drops in oxygen levels and threatening the survival of fish populations.

Inland waterways and coastal lakes and lagoons are also likely to experience fish kills this summer with increasing water temperatures, stratification and no or low flow.

Response actions

Native fish drought response actions undertaken from August – December 2019 to minimise fish deaths include the use of water for the environment, fish rescues and relocations, and aeration or mixing of refuge pools. These actions have been undertaken in a number of at risk catchments.

NSW Native Fish Drought Response 2019/2020

Read more about the NSW Native Fish Drought Response 2019/2020.

Bushfire impacts on native fish

Find information on the impacts of bushfires on native fish.

What is 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

  1. Blue Green Algal Bloom
    Algal flourish in warm and still conditions, particularly in the absence of high flow
  2. Surface Water Layer
    Warm, high nutrient load from run off.
    Dissolved oxygen by day, depletion overnight
    Limited fish habitat
  3. Deep Water Layer
    Cooler, low light penetration, low dissolved oxygen (hypoxia), Poor fish habitat
  4. Decomposition of organic matter
    Depletes dissolved oxygen
For an accessible explanation of this graphic contact the author Sarah.Fairfull@dpi.nsw.gov.au

De-stratification ("Turn over")

Key

  1. Sudden weather events or small increases in flow
    Can mix the warmer surface water and cooler deep water – essentially breaking down the temperature stratification
  2. 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.
For an accessible explanation of this graphic contact the author Sarah.Fairfull@dpi.nsw.gov.au

Investigating and reporting

Recent fish death events

Updated: 16 Jan 2020 (10.00am)

Location and date kill observed

Cause and extent

Murray Darling catchments in NSW

Lower Macquarie River, Oxley Break (Late Oct)

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

The cause is unknown.

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.

Border Rivers, Reedy Creek and Dumaresq River, downstream of Reedy Creek; Tenterfield Creek and Millers Creek in the vicinity of Tenterfield (~24 Nov) Bushfire affected area, with recent heavy rainfall washing ash and soil into these waterway, causing low dissolved oxygen conditions.Species and numbers of fish affected is still under investigation.

Blowering Dam, an isolated bay (late Nov)

Approximately 50 large Murray Cod.

The cause of the kills is under investigation

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.

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.

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.

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.

Peel River, Fishers Lane near Tamworth (12 Dec)Approximately 50 fish including Murray Cod, Golden Perch, and Eel-tailed Catfish reported.

Flow ceased in the Peel River downstream of Dungowan Weir. Suspected cause is no inflows and drying refuge pools during drought conditions.
Bindara Station, Lower Darling (near Menindee), (14 Dec)Approximately 15-20 Murray Cod affected.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows.
Darling River, Upstream of Pooncarie (31 Dec)Less than 10 dead fish reported including Murray Cod and one Carp.

Suspected cause is no inflows and drying refuge pools during drought conditions.
2020
McDonald River, (Alberbaldie Road), (2 Jan)Reports of dead Trout int he upper headwaters of the McDonald River towards Niangla.

The cause of the kill is under investigation. 
Peel River, Tamworth (5 Jan)Approximately 50 dead fish including Murray Cod, Eel-tailed Catfish and Golden Perch.

Flow ceased in the Peel River downstream of Dungowan Weir. There was a large rain event in early January that has since washed debris and organic matter into the river, affecting water quality and dissolved oxygen levels for native fish resulting in this fish kill.
Macintyre River, Dintonvale Road Crossing, Bukkulla (9 Jan)Up to one hundred dead fish reported including Murray Cod, Golden Perch, Freshwater Catfish, Bony Herring as well as Carp (introduced species).

Suspected cause is poor water quality resulting from recent rain increasing flow in the river and washing organic matter and sediment into the system, affecting dissolved oxygen.
Macintyre River, Elsmore Commons (9 Jan)Report of 10-20 dead Murray Cod downstream of Stannifer Road.

Suspected cause is poor quality resulting from recent rain increasing flow in the river and washing organic matter and sediment into the system, affecting dissolved oxygen.
Junction of Severn River and Tenterfield Creek, near Tenterfield (9 Jan)Reports of dead fish following an isolated storm event. Species affected include Eel-tailed Catfish, Carp and Murray Cod.

Likely cause is a drop in dissolved oxygen following the isolated storm event washing organic matter into the river system.
Wallangra Creek, near Glen Innes (10 Jan)Reports of dead Murray Cod and Eel-tailed Catfish.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows.
Upper Gwydir River, near Bundarra (12 Dec)Thousands of fish reported dead including: Redfin Perch (introduced species, 1,000s); Freshwater Catfish (100-150), Freshwater Catfish (100-150); Golden Perch (20-25); Goldfish (introduced; 10-12).

Poor quality resulting from recent rain increasing flow in the river and washing organic matter and sediment into the system affecting dissolved oxygen.

Coastal catchments in NSW

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.

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.

Brunswick River, Main Arm (late Nov)Small event with approximately 25 fish affected (mainly Mullet with small numbers of Australian Bass).

Likely cause is low dissolved oxygen within an isolated pool and minimal inflows.

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.

Killalea Lagoon, (Western End), Shellcove (11 Dec)Reports of approximately 200 dead fish, mainly Mullet.

Suspected cause is no inflows and drying lagoon from extremely warm temperatures.
Summer Island Drain (Macleay), (13 Dec)Reports of approximately 200 dead fish with only Mullet being affected.

Likely cause being low dissolved oxygen within an isolated poo receiving minimal inflows.
Burgess Creek, Bonville Creek (13 Dec)Reports of approximately 15-20 dead fish including Mullet. Fish reported as gasping for breath.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows.
Warrel Creek, Upper Reaches, Nambucca (15 Dec)Reports of approximately 100 dead fish including Australian Bass, Mullet, Bream, eels and Eel-tailed Catfish.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows.
Palestine Creek, Curalo Lake, (15 Dec)Reports of hundreds of dead fish including Mullet and Luderick.

Likely Cause being low dissolved oxygen within an isolated pool receiving minimal inflows.
Broughton Creek, Foxground (26 Dec)Hundreds of fish affected including Australian Bass, Eels, and Gudgeons.

Suspected cause is no inflows and drying refuge pools during drought conditions.
Natural Lagoon, Bega (27 Dec)Reports of approximately 100 dead fish made up largely of Carp.

Suspected cause is no inflows and drying refuge pools during drought conditions.
Mann River, Clarence (27 Dec)Reports of 10-100 dead fish including Eels and Eel-tailed Catfish. Reports of high amounts of ash in the water.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows.
Lake in Dalmeny (exact location unconfirmed), (27 Dec)Reports of 10-100 dead fish in lakes system. Affected species included Mullet and Eels. Exact numbers unconfirmed due to local wildlife consuming fish.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
Bellambi Lagoon (Western Side), Corrimal (29 Dec)Reports of a small fish kill event, predominantly made up of Mullet. Exact numbers of fish affected unknown.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
Clarence River, Baryulgil (30 Dec)Report of approximately 1,000 dead fish specifically Mullet, Australian Bass and Catfish.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
Nambucca River, Taylors Arm (30 Dec)Report of approximately 20-30 dead Australian Bass upstream of Boat Harbour Road.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
2020
Tilba Lake, Batemans Marine Park (1 Jan)Reports of hundred of dead fish specifically Bream, Flathead, Mullet, Eels and Blue swimmer crabs.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions. Soot was also observed at the water's edge from recent bushfire activity in the area.
Limeburners Creek, Hastings River at Port Macquarie, (2 Jan)Reports of thousands of dead fish. Exact numbers are unknown with species affected including Mullet, Bream, Herring and Whiting.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
Minnamurra River, Jamberoo, (3 Jan)Reports of 10-100 dead fish at the Factory Lane Bridge over Minnamurra River. Also reports of fish in distress upstream in the system.

Species affected were largely Australian Bass. Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
Poverty Creek, Clarence River (9 Jan)Approximately 10 Mullet affected along with other small fish observed gasping at the surface.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
Manning and Barnard Rivers, Between Burrell Creek to Bretti (9 Jan)Reports of 100s of dead fish including Bull Trout, Australian Bass, Herring, Mullet and Catfish.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.
Macleay River, upstream and downstream of Bellbrook Bridge (10 Jan - ongoing)Reports of hundreds of thousands of dead fish including Mullet, Catfish, Herring, Bull Trout, Australian Bass and Eels.

Likely cause is isolated large rain events moving mud and ash from bushfires through the river system, resulting in a drop in dissolved oxygen levels for native fish.
Pine Creek, Bonville (12 Jan)

Approximately 15 Mullet and many smaller Mullet observed gasping for air.

Likely cause being low dissolved oxygen within an isolated pool receiving minimal inflows due to drought conditions.

Wallamba River, upstream of weir on Dargavilles Road (13 Jan)Approximately 8 dead fish reported. Cause of this fish kill is still being investigated.