Sounds like some dickhead opened the wrong valve at any one of those major industries in the sound there and let out whatever. Be hard pressed to prove who I guess but you can only hope. What a disgrace. 

 This is just horrible. If it is pollution the company/organisation involved is in deep shit. May be a good idea for fisheries to close fishing in the sound for a season or 2?

 Latest update

www.fish.wa.gov.au/About-Us/Media-releases/Pages/Fisheries-update-on-Cockburn-Sound-fish-deaths.aspx

 I hope they are putting signs up at the boatramps and beach fishing spots to warn people not to consume anything from the area.

• temporarily not to collect or consume fish from the waters of Cockburn Sound; 
• That above comment taken from the Fisheries Latest Update. Cockburn Sound is a large area of water from Rockingham up to Fremantle.
• I would  think that the Blue Lagoon Mussel Farm is affected by this, and that they have stopped harvesting mussels from Cockburn Sound? 
•  

 Today fisheries had meeting with navy. Apparently big school gone belly up again. Over a thousand snapper gone? Over last few days washed up on island. ??They swam in not looking healthy. Then all gone( dead). Second hand info unsure. What a shame still dying.. Once again to little to late. All bans fisheries put in place to protect fish. Gone in week. Stocks where looking fantastic. Then done good job. Must be very toxic to effect outside off big bridge( coat hanger). Crying shame I wonder if anyone will find out what's done it??

 The Daily Mail UK seems to have a lots of info and pic's:

http://www.dailymail.co.uk/news/article-3329284/Locals-left-bewildered-700-dead-fish-discovered-washed-popular-tourist-beach-Western-Australia.html

 to quote a bloke on our closed forums:  "The Navy have been doing radiation testing on the subs in port at garden island last week (testing for cracks I think) may or may not have some thing to do with it... Seems a little suss that dead fish start floating around in the area a few a day later though."

All the good work to promote and foster growth of the largest known pink snapper breeding mass in the lower west coast appears now to have been decimated.

It's bloody outrageous that such a thing has happened, if this is man caused then those responsible must be severally punished.

No slap on the hand stuff and a bit of tut tut what bad luck.

There are no such things as accidents, only events caused by circumstances which have been allowed to happen or gone unchecked.
Good example look at the Varanus Island gas outage, (love that word," outage" stuff up and lack of maintenance).

If a fisherman takes one just one snapper during the closed season he would be hung drawn and quartered by DoF if this catastrophe has been caused by industry , defence or any other human activity then they should be shut down forthwith, immediately, until they can prove that it is safe for them to resume business again.

They should be fined such an amount that their share price will not worth the paper the shares are written on, and made to pay for a stock replenishment programme to rebuild the bio mass.

If it's an arm of government same same no let off.

Am I angry you bet I am, and so should every member of this site. Make you anger known to your local council and state MP as well as your federal member, let them know that if their actions to punish those responsible are not to your satisfaction you will actively support/help any person who opposes them when they next come up for election.

If the cause is an "act of nature" then we should ask DoF via it's minister to seek funds of a size needed to undertake an extensive stock breading programme to assist in getting the bio mass back to sustainable size.

There was a post on this site about what do we do when we don't agree with something, I for one didn't agree with a lot of what was written, I don't feel like a hypocrite when I say that all F/W members should make their displeasure (if man caused) or desire to see these iconic fish protected vigorously.

Sorry for the long post, however I feel very emotional about the loss.

 If the Navy is involved in this, I'm sure it will be a big cover up.

 Yep i'll have a bet on the navy..this is more that a dose of polution from the industrial area. You wouldn't want to swim dive anywhere within cooee of this shit. Hope it doesn't get out to the crays.

 And my dive spot. West side of coat hanger. Such a big volume of fresh salt water there? The ones washing up in front of my work 1 and 2s. Only on South wester. It not disease .oxygen  issue or pollution in my opinion . It hit hard and fast. Feel for guys who depend on sound for income also. It's costing fisheries 500 bucks a fish to test( older dead ones) that's why they need ones still kicking must be cheaper I gather . There doing everything they can. I would like to know how many have been picked up in navy waters . I think the public have the right to know. People who have chased pinks for fair few generations know with big boys go to spawn . Well before causeway was there massive schools would shelter and breed in huge numbers where small boats compound is . Also some goods reads when navy use to clean there hulls and catch huge numbers of snapper feeding on barnacles . Many many generations of pinks always have gone there. I would have to say it's the most pinks I have ever seen this year spawning in sound. There number have increased dramatically .. I think it would be in the thousands( dead ones) we will never know. Not counting the  billions of eggs. I don't know who is responsible  . Would be nice to know the truth. To make sure it never happens again. Waiting game

 Desalination plant??

 could of come from the desal plant, lots of good water goes in and the rest after treating comes out! Into cockburn sound?

Ships Ballast?

I don't know much about Cockburn Sound, but my guess is that this has caused a pretty big dent in the Snapper stocks in there. 700 fish is around 4 ton of Snapper, 1000 fish is 5 or 6 ton of Snapper. That's a huge amount of fish for that area. All the hard work done by fisheries, recs and commercials with closures etc undone within a few days. It's worse than if a trawler got in there and trawled up 6 ton. All these magnificent fish have gone to waste. 

 Wonder if they have shutdown the desalination plant. If this is a chemical spill then they will be processing contaminated water

 ...under natural conditions, something like 95% of those eggs/larvae will not make it to maturity. With what's happened now, you can pretty much bank on 100% mortality rate. As little jonny says, bad result for GENERATIONS of pink snapper. Not to mention the effect on seagrass beds and the entire food chain, which no doubt is a huge reason why the snapper come to spawn there in the first place.

Unless there is an independent analysis done you can almost guarantee there will be a cover-up if the desal plant is involved.

 So we have discussed why this has happened, and I'm sure no one wants to think about this but what will the fishing be like in the future? Will it end up like just a nice place to be?

This is pure speculation ok, what happens to the salt that is extracted from the salt water that comes into the desal plant, is this then discharged back into the sound as super salt content water.

Now that would be a toxic bomb that would be hard to detect.

The case against such a thing happening is of course, why has this not happened before and I'm sure that there would be safe guards against such adverse actions like that happening. Wouldn't there, hey we are talking about a government body here just like the Water corp, and government corporations don't make huge mistakes that's why the heads of these bodies are paid good salaries.

As I have said in my previous post, I don't give a rats who has cause this (if indeed it is human caused) their bloody heads should be put on a plate and served up to the public to view.

I attended a public meeting when the Binninup desal plant was in the planning stage and one of the major concerns was the heavy salt brine that was released lay on the ocean floor and caused oxygen depletion. Theres a few alarm bells ringing for me.

 ...there has never been any trace of cancer detected in sharks. Different physiology from true (boney) fish, and could quite likely be able to endure lower water quality.

To the above comment regarding excess salt content being difficult to detect: checking salinity levels is probably the EASIEST test to perform. 

As I mentioned before, the creatures that live and feed in the upper part of the water column appear to be unaffected. Benthic species, ie urchins, crays, blowies, wrasse, etc...as well as the higher life forms that feed on them(snapper) are the ones copping the brunt of it. Tells me if it IS poison/pollution, would be of the heavy, sinking variety.

Also worth noting that the latter part of last week featured strong offshore winds in the mornings. Which would indicate less Navy and more Kwinana Industry as a possible source.

 I'm only new down here and put the first report on here about the dead fish after seen the floating near garden island and am shocked at all the possible causes , I spoke with a mate who's son works on garden island and is a very keen free diver and fisho he gets the feeling over there that something is not right and the the navy could have something to do with it , and on the day I first saw the fish the navy ribs where scooting about the sound and came to shoo me away for been to close to the jetty when I said I was just looking at all the dead fish the told me to just get out of there . Hope we get some answers soon as there were people fishing an swimming there for days until anything was said .i also contacted fisheries that day and recfishwest who are the only people tha showed any immediate concern and responded to my email directly . 

Largely edited as I was wrong.

According to Navionics, the discharge pipe from the Cockburn Desal plant ends in 8m of water.

 All pure speculation guys. No reason to point any finger until testing results are released. If the desal plant was the culprit there would have been dead fish before now as the plant has been running a few years. 

What is the likelyhood of something really volatile being spilt from ships in the area ?

As far as the Desalination Plant theory, do fish's gills burn from too much salt in the water ? It would make some sense in my mind with the pipe being that lowin the water column.  

The abovementioned mussel farm man on the radio testing for algae also sounds like it could be possible. I'm still tending to think deep down its Kwinana industry. 

it is all speculation, however all caring types (except, except the lounge loving green and environmental types) are waiting with baited breath for testing results to come in and, a survey to be done to try and evaluate just how much damage has been done to the snapper breeding bio mass in the sound.

Just wait until the green and environmental types have a meeting or love in or what ever else they call it when more than two of them get together.

I will give them such a hazing they will not dare to show their faces for a hell of a long time.

 Who could do tests. But I bet not hard to get fresh dead fish if wanted . If they don't know by now something very wrong . Dtrain are you fisheries ?? You are correct radiation doesn't travel far Through water .Hence just outside coat hanger. Small boats compound. Collie ledge. Everything dead within 1 kilometre  off coat hanger. Swam nth end all alive. Even rock crabs  dead Sth end. All big orange ones on rocks gone? Sorry but this is bu$$@'t. Def not industry. Would have been on news and solved. If anyone on site knows someone who could possibly solve deaths of fish. Iam sure most would donate to find out real cause. Gone on to long now. Good news someone I know doing pots seen very healthy fish outside sound. Also different area someone else seen healthy fish outside sound on surface. ??? Why are they there? Should be inside ???? Be like aeroplane  that was shot down. Will never know?? Bet last dollar on that. Sad but true. 

 how come non of the sharks are been killed? there are tiger sharks and bronzwhaler sharks caught everyday at woodmans point.

 Volunteered to give the samples of freshly gutted & scaled herrings & snook that I kept on Sat to  Paul who is doing the post mortem but he politely rejected because he needs fresh dead samples or live kicking ones to test.

Test results should be available for comment tomorrow from what I hear.

Have been told that someone had notified the authorities last week of what happened but did not give name and cant comment on if they gave name of who was responsible.

Not long now.

 He is chasing 1 for an independent  scientist . Who wants 1. I still can't understand why bullseyes and Crays lived on my ledge everything else dead. Can't be poison. Radiation or fish pox( virus). Anything sheltered lived???? For those who don't dive bullseyes live in caves . Spend most day in them mainly come out at night. Let's see results will be good.

 So Timmo what your basically saying is fisheries have known all along from a tip off what happened but just don't know who surly if they know the cause it won't be hard to pin point who's responsible .? 

Eagerly awaiting results :( 

Looks like all the fish that are affected are ones that feed off the bottom, so whatever it is kiling them is located on the seabed. therefore demersals are screwed, pelagic maybe ok???

Recwish West update 25/11/15

"

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

CURRENT SITUATION

• 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.

I strongly suspect that we are only seeing a small fraction of the fish that have been killed. Whilst that is bad enough one has to wonder what damage has been done to the eggs produced by the breeding activity. If they have been killed in large numbers then there is going to be some long term damage done.

Fingers crossed for the future of some great iconic fishing in the future.

 Cransy1 .??? Don't think we will ever find out. Toxins pollutions virus oxygen all taken out equation . Now what ? And who. ? This one has been pushed under carpet. Like all them poor people shot down in aeroplane . To big ???

 Latest Update- Cockburn Sound: Fisheries give all clear for Fishing/ Swimming.

UPDATE ON COCKBURN SOUND FISH DEATHS

FISHING AND SWIMMING OKAY AGAIN IN COCKBURN SOUND

The Department of Fisheries testing on water samples as part of the multi-agency investigation into last weekend’s fish deaths in Cockburn Sound has so far found no evidence of a chemical source being responsible. Biosecurity research scientist Dr Michael Snow said the tests on water and fish tissue samples from the sound had been inconclusive but they did indicate elevated levels of a naturally-occurring bacterium that may be harmful to fish, however, this was unlikely to be the primary cause of the event.

“Testing will continue on samples of dead fish, along with further monitoring of water, but for now health authorities have given the all clear for fishers and swimmers,” he said.

The Department of Health advises people:

• The water is suitable for swimming, diving and other forms of recreation;
• The area is also suitable for fishing; and
• We remind anyone not to swim or fish in water that looks discoloured, murky, or smells unpleasant, or where there are large numbers of dead fish.

Dr Snow said an investigation by the Department of Environment Regulation had to date not identified evidence of a significant reported pollution event in Cockburn Sound.

“Screening of water samples for the presence of harmful algal bloom species and their toxins by the Department of Health has also not identified levels of concern to human health,” he said.

“The search continues for a possible cause, through laboratory investigations on dead fish samples collected from the sound, but the wide range of tests required means that reports will not be available until at least late next week,” Dr Snow said.

“We investigate somewhere between 20-30 fish kills per year in Western Australia. The majority are in inland waters and caused by low water quality often associated with algal blooms.

“The fact this event has occurred in more open ocean means we have less evidence of a direct cause to go on and we are having to explore all possible explanations. It may be the case that a single definitive cause cannot be identified, but we are continuing the search.”

Any fish kills should be reported to FISHWATCH on 1800 815 507.

 It could be that we just pushed the sound to far. Closed half the sound with that limestone going to GI, desalination plant and all the rest, May have only taken 1 little thing to push it over the edge.

 doesn't help that instead of taking action on the Fri/Sat they waited until Monday to take test samples. I'd hate to see the reaction time if there was a huge oil spill for example - will the suitable gov't departments wait until office hours on a weekday to act in that instance too?

 Finally on the Ch9 Facebook page.