Fish Unusual behavior

[Isaac Ct]

I thought this would be worth posting 

Currently the bream population in swan  lake near St. George’s basin is acting strange. Hundreds of them are gathering in the shallows at the mouth of the lake and since it isn’t always open they seem to be wanting to get out. They are all black bream and i was picking 40+cm ones up with my hands. 

They have a white milky cover over there eyes and fins are red. Any idea what is Happening? My thoughts of a chemical spill or something. Photos Will come

Edited January 6, 2023 by Isaac Ct

[James Clain]

Trauma causes the white film to appear on their eyes, red spots sounds like red spot disease. Epizootic ulcerative disease (caused by a fungus). Most common in warmer water as well. 

I'd say this is what's happening to the population. Maybe they are at the mouth to try and escape the waterway and get into more salty water to help clear it up (just a theory).

Maybe some other raiders will have more to add. 

[Green Hornet]

I’ve seen this happen before in Lake Wollumboola, just up the coast from Swan Lake. The general consensus at the time was that like now, after closing just before a lot of rain, the lake had filled quickly causing the salinity level in the water to drop sharply and the fish were trying to escape to the ocean to overcome it. 
During the Wollumboola event, along with the bream were blackfish of a size I’ve never seen before. Hundreds of fish well over 2.5kg.

[Yowie]

The entrance needs to be opened so that the fish can reach a new batch of salt water. Usually it needs an operation from the local council to dig out a new channel to the ocean.

[Green Hornet]

48 minutes ago, Yowie said:

The entrance needs to be opened so that the fish can reach a new batch of salt water. Usually it needs an operation from the local council to dig out a new channel to the ocean.

It’s a catch 22 situation. In the instance I mentioned above the lake was opened by locals with shovels and most of the fish, if not all died. Obviously they couldn’t cope with either the rapid change in water salinity, temperature change, or both.

[bessell1955]

Well that is not good.

[Pickles]

Thanks for sharing Isaac, a real pity, but part of the natural cycle of things.

[dunc333]

keep us updated mate

 

[Green Hornet]

Just an update to this. Swan Lake has now opened to the ocean, whether naturally or manually I'm not too sure, but considering the calm weather conditions of late I suspect the latter.

The bad new is there's now masses of dead fish of several species lined along the banks. 

Sad to see, but certainly not an uncommon occurance in these fragile ecosystems.

[noelm]

I was talking to a pro fisherman the other day and he mentioned the fish in Swan Lake, they call it "puss eye" not very glamorous but I guess it's just a nick name? Said it's common when a lake is closed, then lots of rain, then warm weather, once the water starts to heat up, the fish get disease and most die.

edit......I don't know if that's 100% true, but just what I was told by someone who "might" know.

Edited January 16, 2023 by noelm

[Green Hornet]

 

56 minutes ago, noelm said:

I was talking to a pro fisherman the other day and he mentioned the fish in Swan Lake, they call it "puss eye" not very glamorous but I guess it's just a nick name? Said it's common when a lake is closed, then lots of rain, then warm weather, once the water starts to heat up, the fish get disease and most die.

edit......I don't know if that's 100% true, but just what I was told by someone who "might" know.

From my understanding, events such as this tend to effect the yellowfin and hybridized bream more so than the blacks which are far more adaptable to fresh and low salinity water. Mullet also seem to mostly survive, but blackfish do not.

Speaking of pros, a couple of years ago I saw data of the amount of fish commercially netted in Swan Lake and it was mind boggling the tonnage removed annually. No way in hell would I have thought the lake could sustain it.

[Isaac Ct]

4 minutes ago, Green Hornet said:

 

From my understanding, events such as this tend to effect the yellowfin and hybridized bream more so than the blacks which are far more adaptable to fresh and low salinity water. Mullet also seem to mostly survive, but blackfish do not.

Speaking of pros, a couple of years ago I saw data of the amount of fish commercially netted in Swan Lake and it was mind boggling the tonnage removed annually. No way in hell would I have thought the lake could sustain it.

I was speaking to one of the locals we have know for a while and he said the commercial fisherman in the lake has a 600m drag net and he does it at night. He then sells all his catch to Sydney Fish Markets for cat food!!! It is the only commercially fished enclosed body of water in NSW

[noelm]

They do NOT drag any net, and I doubt any decent quality fish are sold as cat food, and lots of enclosed bodies of water are commercially fished, your "local" is just spreading wild hearsay that's simply not true, and he has no idea.

Edited January 16, 2023 by noelm

[Green Hornet]

1 minute ago, Isaac Ct said:

I was speaking to one of the locals we have know for a while and he said the commercial fisherman in the lake has a 600m drag net and he does it at night. He then sells all his catch to Sydney Fish Markets for cat food!!! It is the only commercially fished enclosed body of water in NSW

They used to do similar in Lake Wollumboola and because of the environment the fish come from, they are dark in appearance and unappealing to the public, hence the pet food scenario.
The “powers that be” that allow this to continue need a good kick in the bum!

[noelm]

The whole professional fishing industry is way more regulated than it was years ago, lots of licenses bought out, big ocean fish Trawlers are few now (and fishing hasn't improved) fishermen can only fish in "zones" If someone wants to fish (say) Lake Illawarra, they have to buy an existing endorsement, then there is fishing methods, a pro can't just mesh anywhere, anytime, days per year are restricted, fishing hours restricted and methods are not just anything you like. You want to trap crabs, you have to buy an existing license, and quota (it's not just take as much as you can) you want to mesh, you buy an existing mesh license for a set area.

Now, let's be 100% clear, I am not anti pro, or cheering for them, there needs to be a balance of information shared, they are not my fish, or yours, they are a finite natural resource. As it stands, Fisheries are having a "best guess" at rec fish take, and adjusting bag and size limits to suit, however, reliable catch data for recs is "fuzzy grey" at best. The pro side has reliable data, through markets and catch records, and like wise, restricted fishing days, quota and methods to suit. 

Its a very complicated resource to manage, "locals" spreading gossip are only doing themselves harm in the long term, if asked for documented proof of dragging 600m nets (no idea how much power that would take, but it won't be a net punt with a 50hp outboard) when such claims are found to be completely false, then their standing has just been shot to hell!

How to collect rec catch data would be a mammoth task, some kind of App or catch book maybe, but most would be too paranoid to complete one, so the "best guess" approach is all the Fisheries have to go on, and reductions in size and bags will continue without verifiable data.

You might have guessed this topic is something I am very passionate about......and you would be right, I have spent a very long time researching how "we" (everyone, including pros)  go about fishing. As it stands, almost all Lakes and rivers are pretty static in catch rates, not declining or increasing for both parties, so, best guess, the balance is close to right, but there is still a very long way to go.

WA is facing a total ban on Snapper, not too sure anyone would like that here, slot limits seem to be a good theory, time will tell on that one, but as it stands, we as rec fisherpeople need to help shoulder the load, just yelling "ban the pros" will get us nowhere at all, they are very well organised, have reliable catch data and documented proof of total allowable catch TAC!

Edited January 17, 2023 by noelm