Cockburn Sound Fish Kill Update

Recfishwest Update

Please find below the Department of Fisheries Media Release regarding the latest on the Cockburn Sound fish kill.

Department of Fisheries Media Release 8 December, 2015 – Breakthrough in cause of Cockburn Sound fish deaths

The Department of Fisheries investigations have confirmed that November’s Cockburn Sound fish deaths were likely caused by a bloom of microscopic algae.

Supervising Scientist Dr Michael Snow said exhaustive testing had isolated a spike of a group of algal diatom species called Chaetoceros spp. which have spines made of silica and are known to causes gill irritation in fish that can lead to mucous accumulation and respiratory failure.

“Similar diatoms have been implicated in fish death events in other parts of Australia and also internationally,” Dr Snow said.

“This bloom may also have been associated with low dissolved oxygen conditions which are known to periodically occur in southern section of Cockburn Sound placing extra stress on the fish. We know from experience that fish death events often involve multiple contributory factors that make cases difficult to solve.

“We appreciate the patience of the WA community as the multidisciplinary investigative team have methodically eliminated many other causes.  We cannot afford to jump to conclusions in these cases which must be based on solid scientific evidence. Investigations have included screening for a wide range of over 120 algal toxins and industrial contaminants including heavy metals, fertilisers, pesticides and hydrocarbons.

“Other Government agencies have also pursued and eliminated a number of other possibilities.

Dr Snow said results received late yesterday – and confirmed earlier today – indicate that the algal diatom is the most likely cause. He said satellite data also showed an increase in surface water temperature at the same time, which may have contributed to the bloom event

“The diatom is 10-50 microns in size, which is similar to the diameter of a human hair,” he said. “Diatoms naturally occur in all marine and estuarine environments. They are not harmful to humans. The Department of Health has confirmed the Sound is safe for fishing and swimming.”

Dr Snow said the Department of Fisheries would continue to monitor fish stocks to assess the long term implications of the fish deaths event. 

“Seasonal restrictions on pink snapper fishing remain in place (due to spawning), as does a ban on crab fishing due to stock declines in recent years and Cockburn Sound is also subject to the annual West Coast demersal finfish closure,” he said.

Dr Snow said the Department of Fisheries would release a public report on its findings and provide it to other departments with a management role in Cockburn Sound, as well as the Cockburn Sound Management Council.


Recfishwest Update as of 27th November 2015

The latest update we received at 4:30pm today which has disappointingly not provided us with any answers as to the cause.

No one has done more for Pink Snapper in Cockburn Sound than the recreational fishing sector. Fishers have a strong sense of stewardship over this waterway, these are the community’s fish, ‘this is like a kick in the guts.’

The recreational fishing community advocated for greater protection of Pink Snapper spawning aggregations over many years; fish spawn in the sound at this time of year and it’s currently closed to protect breeding stock!

We, as a recreational fishing community, are upholding our end of the bargain and this is a massive let down.

With all the resources of government we are disappointed they could not find the answer.

It is over a week since the first fish were reported and we are still no closer to finding out what has happened here.

It is important that whoever is responsible for this fish kill is held to account.

We’ll continue to pursue this issue as best we can.




Recfishwest Update as of 25th November 2015

Recfishwest strives to keep the fishing community up to date about the mystery deaths of fish in Cockburn Sound over the last few days.


  • The Department of Environmental Regulation (DER) has been conducting investigations into the possible cause of the event.
  • The Cities of Kwinana, Rockingham, and Cockburn have undertaken bacterial water quality monitoring at recreational beaches to ascertain safety for recreational swimming.
  • The Department of Defence at Garden Island is conducting similar bacterial water quality tests today.
  • The Department of Health (DOH) is currently conducting phytoplankton and biotoxin tests on and around the mussel aquaculture facility.
  • Laboratory investigations have been limited by the availability of freshly preserved samples.
  • Chemical analyses completed to date on water samples by ChemCentre (verbal report)show no evidence of presence of  significant chemical pollutants that could explain the event.
  • Similarly plankton analysis by the Phytoplankton Ecology Unit (Department of Water) has not identified evidence of toxic phytoplankton that could explain the incident.
  • Analysis of one affected fish’s tissues has indicated abnormal changes in the kidney and liver (Department of Fisheries). Other species are being examined to determine if this is a consistent finding.
  • A potentially contributing, but naturally occurring bacteria has been identified from one dead fish sample. However, this could be due to a stress event since the fish appear to have been feeding normally until their deaths, and display no external signs of disease.
  • DER has found no evidence to date linking any of the industries or outfalls to the event – though some reports are yet to be received.
  • Results of water samples from the Cities of Kwinana and Cockburn show no bacterial water quality impacts.
  • The Department of Fisheries has commenced a modelling process incorporating currents and wind to try and assist with the determination of the origins of the incident

We are making it priority to keep the community informed with any information Recfishwest receive.

Recfishwest Update as of 23rd November 2015

Recfishwest strives to keep fishing community up to date about the mystery deaths of fish in Cockburn Sound over the last few days.

The Department of Fisheries has advised that a member of the public first reported evidence of a fish kill event to FishWatch on 19/11/2015 at 6:48am.


Recfishwest has provided the Fish Health Unit at the Department of Fisheries with fresh fish samples which are currently being tested for histological, bacteriological and toxicological irregularities.

These samples add to fish and water samples collected by the Department of Fisheries since Friday.


We currently don’t have any further information on what may have caused this fish kill event.  We are deeply concerned that our important recreational Pink Snapper stocks that aggregate in Cockburn Sound to spawn at this time of year may have been significantly affected.  Annual stock surveys early next year should help determine the extent of the fish kill impact.


The recreational fishing community advocated for greater protection of Pink Snapper spawning aggregations over many years.  Fishers have a strong sense of stewardship over this waterway, these are the community’s fish and the magnitude of community concern is extreme.

The fishing community are the eyes on the water and have played a crucial role in identifying this latest fish kill and should be applauded for their repeated calls to  the FISHWATCH hotline.


We will continue to keep you informed of any developments.

If you have any further information regarding fish kills, call FISHWATCH on 1800 815 507.

What we Know:

  • A member of the public first reported evidence of a fish kill event to the Department of Fisheries FishWatch on 19/11/2015 at 6:48am.
  • The Department responded by sending Fisheries officers to investigate and collect samples for laboratory analysis on the same day.
  • Subsequently, several other notifications of a fish kill event were reported to the Department of Fisheries late Friday night and over the following weekend.
  • Fisheries and Marine Officers (FMOs) attended Challenger Beach to investigate. They patrolled 1.5km of coastline around the Alcoa jetty and found 108 dead fish (all deceased and in a deteriorated condition). No signs of fish kill were observed off waters adjacent to kill site.
  • On Saturday morning, the Department’s Fisheries and Marine Officers discovered another 350 dead fish in Careening Bay at Garden Island. Further patrols along Garden Island revealed another 150 dead fish.
  • In excess of 700 fish have been reported dead, comprising a wide range of species and size ranges.
  • Department  of Fisheries staff including, Fisheries Officers, Fish Health and Research staff have been responding to the FishWatch reports.
  • Samples of fish have been taken and sent to the ChemCentre (pollutant testing), the Department of Fisheries Fish Health Unit (disease testing) and the Department of Water’s Phytoplankton Ecology Unit (toxic algal bloom testing)  for testing
  • Water samples have also been taken and sent to the ChemCentre for chemical analysis.
  • Results to date have found no evidence of toxic algal blooms.
  • Ongoing site investigations are continuing.
  • Samples of the dead fish have been taken and we are now awaiting results from the ChemCentre – likely to be Friday (27th)
  • The Department of Fisheries is advising the public not to consume any fish caught in the area of the fish kill even