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Thread: Cape Natures Proposal To Poison Rivers

  1. #21
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    Quote Originally Posted by Booger Rose View Post
    Chris

    I've fished a small stream somewhere in the Klein Karoo (spot X) with brown trout, and heard there are plans for cleaning out this river as well. don't know if they will poisen the river system, or try to catch out the trout. do you know about this?
    Unfortunately X is on the radar Eduard. Dean Impson has given a few of us permission to catch out as many of the browns in that stream as possible for relocation into other less sensitive waters. I may get a few guys together and head something like that up in the near future, before it becomes a free for all. I am in the process of sourcing a suitable virgin stillwater to put them into.
    Last edited by Chris Shelton; 13-05-08 at 05:50 PM.
    "Innocence is a wild trout. But we humans, being complicated, have to pursue innocence in complex ways" - Datus Proper

  2. #22
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    I have it on good authority that stream X is off the radar again, because of the difficult topography and geographic layout of the stream, making it impossible to effectively rotenone.

    Phew, huge sigh of relief about that!

    Thanks for the heads up Liam! Much appreciated!
    "Innocence is a wild trout. But we humans, being complicated, have to pursue innocence in complex ways" - Datus Proper

  3. #23
    Booger Rose Banned User

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    dis goeie nuus!

  4. #24
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    thanks for the very informative reply.

    i stil have some questions as to what the overall effect on the biodiversity of the streams will be? i am quite familiar with the rondegat and krom rivers in the cederberg but i am not as much of an avid fisherman as my father, and therefore my interest is not as focussed on how the use of rotenone will affect my fishing activities, but rather what the use of this poiso is going to have on the biodiversity of the area.

    in my addmittedly superficial rsearch into the effects of rotenone, it seems that the poison also has the potential to be a devestating insecticide. one cannot isolate the effect of the chemical around its influence on the fish populations.

    the insect population of these rivers is most likely a much harder thing to document (as a result of insects being small and basically hard to pin down ) and if it is harder to document, what will the reslts of the poison be on the biodiversity of these stram systems.

    prehaps someone could enlighten me in regard to this area of interest.

    Guy Thomas

  5. #25
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    Quote Originally Posted by CTHOMAS View Post
    thanks for the very informative reply.

    i stil have some questions as to what the overall effect on the biodiversity of the streams will be? i am quite familiar with the rondegat and krom rivers in the cederberg but i am not as much of an avid fisherman as my father, and therefore my interest is not as focussed on how the use of rotenone will affect my fishing activities, but rather what the use of this poiso is going to have on the biodiversity of the area.

    in my addmittedly superficial rsearch into the effects of rotenone, it seems that the poison also has the potential to be a devestating insecticide. one cannot isolate the effect of the chemical around its influence on the fish populations.

    the insect population of these rivers is most likely a much harder thing to document (as a result of insects being small and basically hard to pin down ) and if it is harder to document, what will the reslts of the poison be on the biodiversity of these stram systems.

    prehaps someone could enlighten me in regard to this area of interest.

    Guy Thomas
    Hi Guy

    Most of us share the same concerns as you, and justifiably so. From what I have been told with regard to the impact assessments that have been conducted, if administered in small dosages, the long term effects on insect life are minimal. The way it was explained to me is that is much like taking medication for a particular ailment. If the recommended dosages are adhered to, the ailment is targetted. Exceed it, and other vital organs start to shut down. The idea is to take small sections of the river at a time, eradicating the aliens systematically. My thinking is "easier said than done"!
    "Innocence is a wild trout. But we humans, being complicated, have to pursue innocence in complex ways" - Datus Proper

  6. #26
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    Right, my turn on this topic… I have read a lot on this and without going into the complexities of what the guys are trying to achieve, here is a little bit I have found about the subject.


    There has been a project running the Great Smoky Mountains National Park, by chief fisheries biologist Steve Moore, who is re-introducing the native Southern Appalachian Brook Trout.

    Without getting too complicated…
    Although Rainbows Trout are native to the USA, they are contained to certain geographical areas, similar to the way Largemouth and Smallmouth Yellowfish are native to the Orange-Vaal system. Brown Trout are exotic to the USA, so they shouldn’t be there, and then there are cross bread, or un-pure / mixed strains of the Brook Trout (north and south cross), not Cutthroat, that is a pure strain all by itself. The end result is that the Smokey Mountains have Brookies, Pure southern ones and half breeds, Rainbows and Browns in their river system, when only the Brookies belong.

    Steve embarked on a eradication program, but realised that there was little or no way to eradicate all the alien species, instead, he found rivers and streams with natural barriers, tested it was a true barrier, and then started on eradicating the fish from above the barrier.

    They tested that it was a true barrier by electro shocking about 300 meters of river above the natural barrier, clipping the adipose fin and releasing the fish below the barrier. These natural barriers were normally waterfalls of 6 to 8 feet or more. Trout will naturally try and get back to their original territory and after a year, the clipped fish were not found above the falls, the barriers are deemed to be effective.

    The eradication process was done in 2 methods.
    The first was to electro shock as much of the river as possible, this was done to try and recover as many Brookies as possible. These fish were relocated to holding ponds and the other fish; Rainbows, etc… were released below the natural barrier.

    The second was to use a chemical, this is where you prick you ears up… they did not want to use Rotenone, as it’s destruction is well documented, killing everything in the stream, leaving a desert waist land. The rehabilitation of a stream that was in this kind of state, is no overnight process, so this product was rejected. Steve then investigated another chemical called, Antimycin, which does not kill all gilled creatures. I tried to understand the process, but you can Wikki Pedia it, if you want.

    They tested it and found that it had a 100% success rate on fish, but only killed between 20% and 50% or aquatic invertebrates, with almost no effect on the craw fish and crabs. Thus leaving a stream with a relatively healthy population of life, without the fish… they left the stream for a season to regain its lost insects, and then reintroduced the Brookies, into this pristine garden. They thrived…

    There are other benefits to using Antimycin, one of which is that it is easily neutralised with a calcium compound, and there tests showed that a properly neutralised piece of water was easily achieved.

    The park has been working on this for a few years now and to date they have rehabilitated about 15% of the streams contained in the park.

    Without going into the politics of trout eradication form South African rivers, I am concerned that our fisheries department are jumping in feet first, without due diligence to the process and material to be used.

    Are we entrusting our natural heritage to guys who don’t care, are to busy doing “great” thing, and have that “holier than thou” approach?

    I am no scientist, nor a researcher, but if I can find this information, then so can they…

    Currently Steve is on another project, but interspersed with it, he goes around the States lecturing and train other National Parks members on this process.

    If any of the guys involved in this project would like to contact Steve, you are most welcome to PM me and I will gladly give you his phone number and email address.

    Just my thoughts...
    Mike McKeown

    You're either fishing or waiting...

  7. #27
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    Mike .. thanks for the informative and encouraging post.

    It has always been my greatest worry that our indiscriminate use of Rorizone will eradicate ALL aquatic life. It is just a pity that our "experts" have not taken cognisance of this project!!!
    I always wanted to be somebody,but now I realize I should have been more specific.
    Alcohol is the anaesthesia by which we endure the operation of life. GBS

  8. #28
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    My question is if you take fish an insect life out of a river sytem what affect will that have on the ecosystem?

    Lets say you only irradicate fish, this means animals such as otters and Fish eagles and other birds loose their primary food source.

    The same thing applies if you irradicate insects!

    So if you look at the bigger picture yes our yellowfish have dissapeared from a lot of our waterways but at what expense will it be to get them back into our systems?
    The closer one gets to realizing his destiny, the more that destiny becomes his true reason for being! Paulo Coelho

  9. #29
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    Quote Originally Posted by Jasper View Post
    Mike .. thanks for the informative and encouraging post.

    It has always been my greatest worry that our indiscriminate use of Rorizone will eradicate ALL aquatic life. It is just a pity that our "experts" have not taken cognisance of this project!!!
    It's a case of, "got rotenone, will use!"
    "Innocence is a wild trout. But we humans, being complicated, have to pursue innocence in complex ways" - Datus Proper

  10. #30
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    Quote Originally Posted by Chris Shelton View Post
    It's a case of, "got rotenone, will use!"
    Chris you hit the nail on the head

    They using any excuse to get rid of the stuff
    The closer one gets to realizing his destiny, the more that destiny becomes his true reason for being! Paulo Coelho

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