Freshwater Crayfish in South Africa

Discussion in 'Invertebrates' started by Aninhas, 25 Nov 2015.

  1. Aninhas

    Aninhas

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    Hey everyone,

    I am from Stellenbosch and I am interested in the invasive freshwater crayfishes in South Africa (mostly the Australian redclaw). I have seen some interesting posts here in the forum about them, but I was wondering if you guys have seen some around recently.

    They are very invasive and pose a great risk to freshwater fish, because they destroy their nests, eat their eggs and fry, as well as vegetation and other macroinvertebrates.

    I know they are very abundant in the Komati River, but I was wondering if anyone has seen them outside that area.

    Thanks for the help!
     
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  3. TaahirS

    TaahirS MASA Contributor

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  4. 459b

    459b Moderator MASA Contributor

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    Are you looking for info for a research project?
     
  5. Krushto

    Krushto

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    Hi Annihas,

    If you are referring to Cherax quadricarinatus, yeah they are quite abundant in the water systems around the Pongola region and in the Pongola Dam itself, and have also been found occurring in the Storms River. They have also been noted occurring in a few rivers in Limpopo, closer to Polokwane.
    There is literature supporting their occurrences in SA, and I am aware of a paper in progress for the Pongola region as it forms part of a massive Water Research Council project done in collaboration with UJ and NWU.

    Others which have been found in SA include Cherax destructor and Cherax cainii.

    Hope this helps, if ou need any more assistance you can contact me.
     
  6. Aninhas

    Aninhas Thread Starter

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    Yes, 459b, it's for a research project I am working on.

    Krushto, wow, thank you so much for the very detailed information, you seem to be on top of the issue. I would be very interested in discussing this further with you, but I can't send private messages until I have at least 5 posts. Can you perhaps send me a private message so that we can talk further?

    Thanks a lot!
     
  7. Krushto

    Krushto

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    Yeah I did my MSc in aquatic health so came across them a few times while sampling...
    Sure sending the PM now bud
     
  8. RiaanP

    RiaanP Moderator

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    Eish, I would like to tag along on this discussion. Please keep us updated.
     
  9. Krushto

    Krushto

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    Lol sure thing Riaan,

    Basically, to update on my previous post, along side with @Aninhas's posts...

    There are several invasive crayfish that are inhabiting South African waters, some isolated to specific regions where they are thriving, others where they get introduced, live a while and die off.
    One of which, Cherax destructor, is often found for sale on gumtree and junkmail, and was found in fisheries near Gariep dam, as well as in the dam itself by my supervisor many many years ago.
    Another, Cherax tenuimanus, is found in the Eastern Cape, while Cherax cainii has been found in the Western Cape.
    However, Cherax quadricarinatus has been found in the Ndumo game reserve, as well as water systems in Pongola and the Pongola dam. It has also been found in Limpopo, presumably through being introduced through the Komati River. Samples from the Pongola Dam are currently being studies at UJ for biomarker responses.

    One aspect often neglected when invasive organisms get introduced, is the impact these organisms have on the endemic biota, such as the introduction of parasites and diseases which our local animals might be completely unprepared for. As mentioned with my supervisor finding the C. destructor at Gariep, that had occurred by chance as some were just hanging around picking at fish in the nets, but closer inspection revealed that they had brought some parasitic temnocephalans along with them.
     
    Last edited by a moderator: 26 Nov 2015
  10. Krushto

    Krushto

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  11. RiaanP

    RiaanP Moderator

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    As far as I know fresh water crayfish are illegal. Seen them at shops. Not sure how they get them in?

    Rather small shrimps and easily looked over. They are beautiful.
     
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