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Thread: High flow (Vaal) = Fish KILLS ??? (LM Yellows?)

  1. #11
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    You guys are spot on.... it is bloody serious, but I just wanted to get a smile out of you....

  2. #12
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    If memory serves me correctly one of the major proponents of fish mortality in this type of situation is the release of nitrates from the substrate.
    Decomposing plant matter releases n2 and n3 and this gets trapped in the silted substrate. When the silt is disturbed the n2 and n3 are released. If my reccollection is accurate, n2 is not harmful but the n3 is a real fish killer.
    (Hence why most aquaria have gravel filters)
    Last edited by markdej; 01-02-10 at 03:44 PM.
    "All you need is ignorance and confidence and the success is sure." - Mark Twain

  3. #13
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  4. #14
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    If the fish are dying in this flood, guess who is responsible, if you really get down to basics?

    The Human Race.

    Why? The Vaal Dam is artificial. It was built by us. Now too much water is entering our man-made marvel, and we release a bucket load. Now it floods...and some fish take strain. The flood is our fault, not nature's.

    If there was JUST the Vaal River, as it was many centuries ago...guess what? It would be flowing pristine (like a NZ river), be crystal clear, be healthy as can be, free of toxic waste, free of pollutants, and would only be subject to the odd flash flood...which will be really minimal. The flow would NEVER be as high as it is now, if there were no dams.

  5. #15
    FlyFanatic Banned User

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    Mike, remember that way of thinking when you open the tap to get some water or when you take a nice bath/shower.. Such is life, one creature survives by opressing others, we being the top of the food chain thus being the opressors. I agree its sad, but without the Vaal Dam, Joburg would not be as it is and SA would probably be not a patch to what it is today..

  6. #16
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    Quote Originally Posted by FlyFanatic View Post
    Mike, remember that way of thinking when you open the tap to get some water or when you take a nice bath/shower.. Such is life, one creature survives by opressing others, we being the top of the food chain thus being the opressors. I agree its sad, but without the Vaal Dam, Joburg would not be as it is and SA would probably be not a patch to what it is today..
    Yeah, I know all that, and yes...we all reap the benefit of "technology" and ease of services.
    But, in the same breath, we have to remember that certain things will happen (like the Vaal river floods right now) and we are responsible for it.

  7. #17
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    Sadly I can confirm the reports, I went Saturday to the river to behold the awesome water way becoming more awesome, at the barrage I saw lots of dead fish and when I went to Arends, they told me that they had to remove 11 big bins full of fish from their banks, while there I saw hundreds of fish drift by.

    Here are some pictures
    PK

    I am haunted by waters - Norman Maclean

  8. #18
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    Hi PK,

    Could you give us an approximate summary of which species and sizes and so forth ?

    TIA,

    -B
    "Hierdie drol het baie vlieë" - Ago 2014.

  9. #19
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    Quote Originally Posted by Scythe View Post
    Hi PK,

    Could you give us an approximate summary of which species and sizes and so forth ?

    TIA,

    -B
    Hi Bertu

    Very difficult really.

    There was basically at the barrage in that groups of dead fish carp, smy, lmy, muddies, and moggel. I did not see any barbel between the dead. Average size was in the 1.5 kg size bracket. The biggest fish I saw was a carp that looked like it could push 6kg.

    The fish I saw rushing past at Arend's was way too far out to determine species, but some of them looked really big. I would guess that there was fish of up to 7kg maybe even bigger that came past.

    The caretaker at Arends told me that after the initial floodining the picked up and filled 11 of their rubbish bins with fish, and he said that some of the yellows was really big ones.

    So like I said very difficult to say too much with certainty.
    PK

    I am haunted by waters - Norman Maclean

  10. #20
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    So we had big floods in 2006, 2002, 2000, 1998, 1996, 1991... granted its been a while since the Vaal was flushed, but it is good for the system.

    Allot of rivers in the States now have mandatory flood periods, trying to emulate the natural floods the rivers would have had. It is making a huge impact and in some rivers a small "test" population of stocked Salmon are actually getting quite large, and we are talking down into California.

    Personally, I firmly believe that the Vaal needs a controlled flood and run at 400 to 500 tons for at least 2 weeks in Sept/Oct every year, with a boost of say 800 tons for a day or 2.

    Looking at the alpine streams, spoke to TK yesterday, and he tells me the upper Bell is fishing better than it has in a very long time, this is probably due to the high water last year Feb, then good rains till winter, then good snow, and now good rains again. He says you don't find the tiddlers that normally pester you all day and the bigger fish are shaped like rugby balls.

    So is high water a problem?? I think that if the Vaal was flooded annually, we wouldn't run into this kind of issue.
    Mike McKeown

    You're either fishing or waiting...

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