Bear
05-01-2003, 11:57 PM
Guys,
just read a post on another forum from Frank Prokop about Bream with sores on them in the Swan and Canning.
Has any one seen anyhting like this on the Bream they have caught. I have copied Frank's post below.
Stages is right - this is a potential huge problem and one that needs very careful attention.
I gave big coverage to the acid sulphate problem on my last show on the ABC (thanks for the support from our radio station (NOT), and there are bores in the Karrinyup area putting out water at a pH of 2 - this is a stronger acid than lemon juice!!!! It is caused by cutting into iron and sulphur rich peat or organic soils that have been water logged (read around all the sand lakes and much of the south-west and south coast). When exposed to air, the sulphides oxidise forming SO2 and then when water passes over them they become H2SO4 which is sulphuric acid. Although not as stron, the iron compounds become ferric acid.
Think this isn't a problem?? 15 years ago I was working at the Grafton Research Hatchery and they started finding mullet, bream and herring (Richmond river herring not ours) with ulcers exactly as described here (I have seen them nearly twice the size of a 50 cent piece and almost through to the bone. It is red spot disease and after many years, the primary cause was found to be acid soil run-off leading to a variety of bacterial and fungal atacks. Yes Ando an injury makes it worse but what really happens is that the acid water affects the function of the mucous producing cells in the skin of the fish, reducing mucous (protects fish from all sorts of attacks) and allowing the secondary agents to attack the fish. The acid water also puts the fish under low level stress which also makes them more susceptible to a variety of diseases.
Fish like bream and mullet are particularly susceptible as they spend time in upper reaches of rivers in summer when natural flows are low and acid likely to be more concentrated.
And the longer term consequences??? I'm not saying that it will happen but the Manning and Hastings Rivers (that were thought to be immune from acid sulphate problems) wereclosed to commercial fishing (and a warning for recreational fishers) for two years to allow fish stocks to build up after massive kills associated with acid run off.
Of course the invertebrates are also impacted upon. It may be one of the reasons why the school prawns have all but disappeared from the Swan.
Keep an eye on this one as it is an important emerging issue.
In the meantime - keep the specimens that have obvious ulcers. Freeze the fish immediately (whole) and get it to a Fisheries Office. Dr Brian Jones (who is one of the world's best fisheries pathologists) works for WA Fisheries and would like to see some of these fish to test for red spot implicated organisms!!
Happy New Year to you all.
Sometimes leadership has a cost, but sometimes the outcome is worth the effort. Recfishwest - trying to ensure your fishing quality.
just read a post on another forum from Frank Prokop about Bream with sores on them in the Swan and Canning.
Has any one seen anyhting like this on the Bream they have caught. I have copied Frank's post below.
Stages is right - this is a potential huge problem and one that needs very careful attention.
I gave big coverage to the acid sulphate problem on my last show on the ABC (thanks for the support from our radio station (NOT), and there are bores in the Karrinyup area putting out water at a pH of 2 - this is a stronger acid than lemon juice!!!! It is caused by cutting into iron and sulphur rich peat or organic soils that have been water logged (read around all the sand lakes and much of the south-west and south coast). When exposed to air, the sulphides oxidise forming SO2 and then when water passes over them they become H2SO4 which is sulphuric acid. Although not as stron, the iron compounds become ferric acid.
Think this isn't a problem?? 15 years ago I was working at the Grafton Research Hatchery and they started finding mullet, bream and herring (Richmond river herring not ours) with ulcers exactly as described here (I have seen them nearly twice the size of a 50 cent piece and almost through to the bone. It is red spot disease and after many years, the primary cause was found to be acid soil run-off leading to a variety of bacterial and fungal atacks. Yes Ando an injury makes it worse but what really happens is that the acid water affects the function of the mucous producing cells in the skin of the fish, reducing mucous (protects fish from all sorts of attacks) and allowing the secondary agents to attack the fish. The acid water also puts the fish under low level stress which also makes them more susceptible to a variety of diseases.
Fish like bream and mullet are particularly susceptible as they spend time in upper reaches of rivers in summer when natural flows are low and acid likely to be more concentrated.
And the longer term consequences??? I'm not saying that it will happen but the Manning and Hastings Rivers (that were thought to be immune from acid sulphate problems) wereclosed to commercial fishing (and a warning for recreational fishers) for two years to allow fish stocks to build up after massive kills associated with acid run off.
Of course the invertebrates are also impacted upon. It may be one of the reasons why the school prawns have all but disappeared from the Swan.
Keep an eye on this one as it is an important emerging issue.
In the meantime - keep the specimens that have obvious ulcers. Freeze the fish immediately (whole) and get it to a Fisheries Office. Dr Brian Jones (who is one of the world's best fisheries pathologists) works for WA Fisheries and would like to see some of these fish to test for red spot implicated organisms!!
Happy New Year to you all.
Sometimes leadership has a cost, but sometimes the outcome is worth the effort. Recfishwest - trying to ensure your fishing quality.