Cockburn Sound Fish Kill - Considered Hypothesis
There has been much discussion about the “mystery” of the Cockburn Sound fish kill over the last couple of weeks. I have read it with interest, and have a career of dealing with pollution issues and management of hazardous sites. I have investigated a number of fish kill instances, and have had to respond to environmental emergencies for clients to direct works so as to prevent pollutant release.
In my opinion, the fish kill was caused by an acute toxic event that was short lived. The fish were previously healthy (undigested food in the gut) but were killed in an instant. The event was indiscriminate as a number of fish species were killed by it, including cephalopods, bivalves and everything else as well.
When a pollutant is added to water it will mix, dependent on a number of factors. This will create a “plume” that disperses based on the conditions that prevail. The concentrations of the pollutant, and whether it will kill biota on contact, will vary throughout the plume. It is a complex science, particularly in an estuarine environment.
My hypothesis is, and it is only a hypothesis, that there has been a spill of a strong acid or a strong base, or a deoxygenating substance, that has been released to waters in significant quantities. Fish, and other marine life is killed instantly if it has to swim or exist in water (the plume) with a pH lower than 3 or greater than 11, or dissolved oxygen <1mg/L.
There are a number of other pollutants that will also indiscriminately kill biota instantly in a plume, again adding to the uncertainty of the cause of the event. I don’t think there is much doubt that the event is a chemical spill of some type however.
Will the Government find the business that caused this, probably not. In a lot of situations the plume disperses and is gone and no “after event” testing will ever discover the real cause of something that diminishes to background levels over a few hours. I suspect that this is why there has been no cause identified. I would expect fish biologists to shed some light on the mechanism of mortality when all the detailed autopsies are complete though.
The loss of the big breeding pinkies is a tragedy. I note there have been further recent reports of fish deaths but I would think this is a residual “wash up” of the original event where dead individuals are only “floating” now.
Anyway, that’s my opinion for what it’s worth.
Ability is what you are capable of doing. Motivation determines what you do. Attitude determines how well you do it - LH.
grantarctic1
Posts: 2546
Date Joined: 03/03/11
Apparently
Apparently , all of us .
So dissapointed and broken hearted at all the good work done, by us Rec's and others. All gone now and we have to swalow this crap.
Broome lad
Posts: 191
Date Joined: 16/11/15
Ch 9 news
Tonight CBH confirms half a ton of canola was accidentally spilt into Cockburn sound last month ? Coincidence or cause ?
Moking
Posts: 1252
Date Joined: 30/05/12
"Silence is Golden"- I keep
"Silence is Golden"- I keep hearing this song in my mind for some reason:
It's a oldie but good!
https://www.youtube.com/watch?v=n03g8nsaBro
My Dad taught me how to Fish-Thanks Dad.(RIP)
little johnny
Posts: 5332
Date Joined: 04/12/11
Lol painfull
Song. Old fella. Gee you listen to crap:):):)
Mick C
Posts: 605
Date Joined: 26/12/13
Natural Causes
Right, driving home from work after having to deal with multiple suppliers that don't care about customer service, and I finally hear from a Government Minister about "the Great Pinkie Tragedy". "The Sound has improved heaps over the last 10 years and the fish kill is likely to be due to natural causes". I must say I nearly choked.
OK, let's have a bit of a look what those natural causes might be. There are indeed some events that can cause "natural" fish death, but I am not sure any of the conditions in late November would have triggered the response that is characteristic of an acute toxic event. Some of them are below.
Algae - various types of algae (Blue-Green for example) can bloom and produce toxins that are harmful to marine life. Blooms have not been reported and appropriate water quality testing would detect toxic microorganisms - not likely on the current evidence.
Water Stratification - you sometimes get fairly laminar flow in water bodies whereby there is minimal vertical mixing. The lower water layers can become anerobic due to a number of factors and then there is turnover, where a large volume of low oxygen water is brought to the surface. This is usually experienced in deeper water bodies such as lakes, and the Sound appears well mixed, so is therefore unlikely on the current evidence.
Release of Low Oxygen Water from Inland Water Bodies or Wetlands - sometimes inland water bodies and wetlands have water that has been resident for a long time that is deoxygenated by breakdown of organic matter and becomes "bad". An event that flushes this "bad" water into adjacent waters with biota can have toxic consequences. I'm not sure the rainfall event in mid November provided sufficient volume to to flush anerobic waters into the Sound.
Acid Sulfate Soils - thest types of soils are fairly common in the low lying areas around Perth. I won't go into the science of them but if interested you can find this out by a Google search. Suffice to say the lowering of the groundwater table can cause potential ASS to become actual ASS and water coming in contact with the soil becomes acidified and can carry dissolved metals that are toxic to aquatic organisms, apart from the acidity. This type of event is usually caused when there is an extended dry spell followed by rain that will percolate into the soil, become impacted and then flush to adjacent waters. Acid waters can also be created by land development and dewatering works but this is not a "natural cause". As above, I'm not sure the rainfall event in November would have created this situation.
Temperature Variations - due to prevailing climatic conditions, water temperature can become unsuitable for the organisms that live in it. It was quite hot around mid-November (during the Test Match) but there have been some statements from experts that indicate the water in the Sound did not become super-heated. Of all the "natural" causes this one may be more likely that others - although I have no data and the comment is pure speculation.
Disease - populations of organisims can be subject to disease outbreaks (there are plenty of events in history that demonstrate this). Death from disease is generally a slower process that what the evidence suggests happened (undigested food in the dead fish gut). Diseases usually have a specific method that cause death and fisheries biologists would probably pick this up.
There are other "natural" causes, but in my opinion these are probably the ones that are possible in this circumstance. Not sure that any are really likely though, although I don't have a strong fact base to go on.
Ability is what you are capable of doing. Motivation determines what you do. Attitude determines how well you do it - LH.
Mick C
Posts: 605
Date Joined: 26/12/13
Lightning
I have also heard speculation that the lightning storm on Saturday 14 November, where there were many reported strikes over the Sound, could have caused the mortality. Lightning kills people so it "may" have the same consequence to aquatic organisms. This "natural" cause is probably worthy of a bit more investigation, via a search of published litereature on the subject. Again, fisheries biologists should be able to identify death by electric shock.
Ability is what you are capable of doing. Motivation determines what you do. Attitude determines how well you do it - LH.
ROCKPOM
Posts: 625
Date Joined: 23/04/07
Good Info Mick!! just a
Good Info Mick!!
just a shame 15years of research and stock enhancement washed down the drain!
Newby101
Posts: 29
Date Joined: 04/02/15
There is something I would like to add.
The amount of discussion going on on this feed is amazing. It indicates the level of concern these events have evoked in so many of us.
I have been reading every bit of information I can get on any progress with finding the cause of this terrible event. Today I discovered one very disturbing fact.
That is: The Barnett government closed the Cockburn Sound Managment Authority. There job was to monitor water quality in Cockburn Sound. According to the article the Sound is under excessive environmental pressure because of industry, the Navy Base/Cuaseway, and population increase in the area. The Cockburn Sound Management Authority was set up to monitor oxygen levels, water temperature and pollutants in the sound to ensure that this, vital area, would be protected and that weater quality would not be compromised. The Barnett Government closed the Cockburn Sound Management Authority. We are now seeing the results.
I congradulate Mick C on your informative narrative of this event. It provides a valuable perspective. So important in these times. Thank you Mick C
David.
Newby101
Posts: 29
Date Joined: 04/02/15
And they Merged the Swan River Trust with Parks and Widlife
And they merged the Swan River Trust with department of Parks and Wildlife and cut their 2014 - 2015 budget by $11 million dollars. I often wonder, was this done to fund the construction of the build of Elisabeth Quay and a footbridge to nowhere? Monument to yet another premier.
I don't hold any political alegences. But I am passionate about our beautiful country. Negligent and delinquent treatment, by govenment, of our natural environment should not be tolerated by any of us. I urge you all to write to your local MP and demand that the Cockburn Sound Management Authority be re-established forthwith. And that the Swan River Trust, (or equilelant authority), be re-established to monitor and protect the Swan River.
Without these bodies to monitor our precious and fragile, rivers, esturies and oceans we will not be able to combat any threats that occur. (Like the current threat).
We need to act. I will write to my local MP tomorrow. If we all do the same something will happen. If we do nothing, Then nothing will change.
It's up to you, us, we.
A collective will bring about change.
David
Howard George
Posts: 544
Date Joined: 10/03/11
Dead Zone.
They're now talking about a dead zone in Cockburn Sound devoid of sea life. The West .com.
Mick C
Posts: 605
Date Joined: 26/12/13
Natural Event Due to Poor Flushing?
In reviewing the article in the West Australian I was a little disappointed to see this comment:
Fisheries biodiversity and biosecurity scientist ….. said the results of exhaustive testing — including tests for more than 120 industrial contaminants — pointed towards a “natural event”.
“Episodes of reduced water quality have been periodically recorded in the southern section of Cockburn Sound by monitoring undertaken by the Cockburn Sound Management Council in recent years,”. These are thought to be linked to poor water circulation in the area.”
Is this right? Being the curious type, I had a bit of a look at the data on tidal conditions over the days when the deaths were likely to have occurred. The chart is below.
This data certainly does not point to a poorly flushed system at the time! I agree that lack of flushing which makes the water “bad”, as described above, can be a natural event but my quick look at the available evidence doesn’t suggest that there is a high probability of this. Testing for contaminants a long time after the event rarely shows anything, for the reasons I have previously explained.
Ability is what you are capable of doing. Motivation determines what you do. Attitude determines how well you do it - LH.
Walfootrot
Posts: 1386
Date Joined: 23/07/12
“natural event”. my ass, once
“natural event”. my ass, once that lime stone dam went from PP to GI the sound started to die, will never flush like it should with that thing stopping flow.
More drum lines, kill the bloody sharks!
uncle
Posts: 9355
Date Joined: 10/02/07
I can see it now
Due to the natural fish kill and loss of eggs etc we would like to ban snapper fishing for a full year.what are the chances of further restrictions
all aggressive fish love bigjohnsjigs
aaasnapper
Posts: 218
Date Joined: 15/01/10
If needs be I have no problem
If needs be I have no problem banning snapper fishing in the sound indefinitely until such time the cause and impact of the fish kill has been determined
null
uncle
Posts: 9355
Date Joined: 10/02/07
Despitely need
A whistleblower
all aggressive fish love bigjohnsjigs
Kakkerlak
Posts: 114
Date Joined: 26/03/15
Recent comments in the news
Recent comments in the news point to canola spill of 500kg two bath tubs full. I struggle to believe that such a "small" amount in such a large high energy body of water could have effected the BOD to such an extend that so much have died. Mich what's your thoughts?
Mick C
Posts: 605
Date Joined: 26/12/13
Grain Spill
Half a tonne of material with a moderate BOD is probably unlikely to have caused the widespread deaths. If I was investigating it, I would want to see the actual data on the mass balance of product (companies keep this data as it relates to cost) to determine exactly how much was lost. Company statements are not always reliable in my experience, however I am not suggesting this is the case. Data verification is always good though.
Ability is what you are capable of doing. Motivation determines what you do. Attitude determines how well you do it - LH.
linoc
Posts: 96
Date Joined: 21/11/15
So listening to 6pr most of
So listening to 6pr most of the day, this morning there was allot of discussion incl on the news re why no answers yet etc.
Perhaps the pressure got to them to provide an answer cause sometime around lunch they announce its due to Algal Blooms, some type that is invisable that has spikes which attach to the gills...
So would this affect all the various sea creatures that have died?
Mick C
Posts: 605
Date Joined: 26/12/13
Adding to Original Post
Just adding this to my original post, as I wrote this in another thread, for completeness.
Through this debate I have tried to be objective, and inform Members about the possible mechanisms of fish kills from my personal experience in having to deal with these matters in a number of instances. Do I genuinely believe the explanation provided through the media, no I don't. It is possible, but so are a lot of other causes.
As Jason indicates, it is all about the evidence. The community has not been provided with the data, other than being told that Fisheries will release a report at some time in the future. The critical evidence to test their hypothesis is the algae concentration (organisms per millilitre) and dissolved oxygen levels (milligrams per millilitre) in the water at various locations at the time or very soon after, the fish were killed. This information must be compared to published (peer reviewed) data that showed the concentrations will, in all probability, kill fish.
Unfortunately, I believe the response by the agencies was too slow. Relevant data must be collected quickly, because as explained in my other post the reliability of evidence diminishes within a short time frame. I am convinced that we will never really know the "true" cause with an acceptable level of certainty, however the Fisheries report may prove me wrong.
Ability is what you are capable of doing. Motivation determines what you do. Attitude determines how well you do it - LH.