Re-introduction of fish into local waters

Discussion in 'General Discussions and Advice' started by 459b, 11 Apr 2011.

  1. 459b

    459b Moderator MASA Contributor

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    There have been a number of threads/posts recently regarding the topic of re-introducing locally caught fish back into the sea. A lot of reefers feel that this practice poses little to no risk to out local ecosystems.

    It is easy to list examples of the devastation caused by the introduction of foreign species. Most recently we have seen reports of the destruction caused by the lionfish in the Caribbean. The highly predatory fish are eating there way through the reefs, with no native species being able to control their invasion. A similar example is the giant snakehead (Channa micropelte). Native to the warmer waters of South East Asia, this fish is now abundant in stretches of rivers in North America. Its spread has been traced back to the introduction of just two fish into a small tributary. Locally, we have the European crab (Carcinus maenas). Another highly aggressive species which is out competing our local crab species.

    Besides the problem of predators, what is of more concern is the introduction of pathogens. As hobbyists we know of a handful of diseases and can only identify large external parasites. A large number of lethal fish parasites are internal and infected fish show little/no visible signs of infection. Diagnosis of these parasites can only be done post mortem and by a qualified individual.

    The problem with parasites is not new. A study by Barker et. al (1994)* identified 18 species of digean trematodes in the 39 species of pomacentridae fish they investigated. More importantly the trematodes showed very little host specificity.

    If you thought fish were the only things we needed to consider, here is an excerpt from a recent study by McDermott et al (2010)** :
    “Approximately 130-140 species of the > 850 known hermit crab species are parasitized by 149 species in 9 phyla, and 27 species are hosts for 17 potential parasites in 5 phyla. Among the confirmed parasites, 30 species of parasitic barnacles (Rhizocephala) and 83 species of parasitic Isopoda are known. Species in other groups of parasites are few in number: Apicomplexa 2, Dinoflagellata 1, Microsporida 2, Ascomycota 1, Platyhelminthes 8, Acanthocephala 2, Nematoda 3, and Nematomorpha 2.”

    “Limited information shows that hermit crabs are first or second intermediate hosts for coccidians, cestodes, trematodes, acanthocephalans and nematodes.”

    The list of examples is rather long.

    What everyone needs to understand is that it’s not only the things we can see with the naked eye that we need to worry about. The parasites we may introduce into our oceans is cause for concern. Some parasites have complex life cycles, including many different intermediate hosts and may even have highly resilient dormant phases. Just because your fish look healthy, it doesn’t mean they not harbouring some viscous

    I’ve spoken to a number of fish parasitologists and the threat is not something we should take lightly. Parasites have been identified in imported fish which do not occur in out waters. Pointing out that sewage or chemicals or man made structures causes more damage to our oceans has no place in this argument. Thinking parasites are insignificant and nature balances itself out, is also narrow minded.

    We cannot be complacent or apathetic abut this topic. It is a problem and one that we can do something about. Re-introducing fish/coral/invertes is not a matter of debate. If you take something out of the ocean and put it in a tank that has anything in it that has been imported (including liverock), then it cannot go back into the ocean. Rather donate it or kill it ...or better still, don’t collect something you cant look after.




    * Barker, S.C., Cribb, T.H., Bray, R.A., Adlard, R.D. Host parasite associations on a coral reef: Pomacentrid fishes and digenean trematodes. (1994).Int. J. Parasitology.24(5): 643-647.


    ** McDermott, J.J., Williams, J.D., Boyko, C.B..The unwanted guests of hermit: A global review of the diversity and natural history of hermit crab parasites. (2010). J Experimental Marine Biology adnEcology. 394 (1-2): 2-44.
     
    Last edited: 11 Apr 2011
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  3. FransSny

    FransSny

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    Well said dave :thumbup:
     
  4. Nsteyn

    Nsteyn

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    Yeah, i am with you on this one. Tnx for the info.
     
  5. richardmatlock

    richardmatlock

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    I too agree,

    That said my released fish are never in contact with any organism that isn't local to their capture site, and they are often returned to the exact site from where they were captured (as were the lionfish that I released a fortnight ago).
     
  6. Nemos Janitor

    Nemos Janitor

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    100% Dave. This is why propergation permits are very difficult to obtain.
     
  7. AfricaOffroad

    AfricaOffroad

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    I was thinking of getting a population of breeding yellow tangs going off the north coast. Imagine, all you up country okes could come down here on your annual holidays and catch your own yellow tangs.

    To the biologists out there, how many do I need to release to get a viable population going?
     
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  8. richardmatlock

    richardmatlock

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    Minium R50 000 fine per species released plus time with Bubba in the big house(last time I checked about 5 years ago)- "Do you feel lucky, punk?"

    On another note, you will need an infinite number, their pelagic eggs and juvenile stages imply that you will actually be stocking the Agulhas bank off Cape Town with yellow tanks (where they will definitely die).
     
    Last edited: 11 Apr 2011
  9. AfricaOffroad

    AfricaOffroad

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    Those are local juvenile pyroferus tangs officer:whistling:
     
  10. LuckyFish

    LuckyFish MASA Contributor

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    Tell me about it.:(
     
  11. 459b

    459b Thread Starter Moderator MASA Contributor

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    AfricaOffroad - are you being serious???
    A. pyroferus is an Indo-pacific species. I think you trying to be smart about one of the local Ctenochaetus species.
     
    Last edited: 11 Apr 2011
  12. richardmatlock

    richardmatlock

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    I've got a pyroferus from the Transkei - the ONLY one caught there as far as I know.
    [​IMG]

    thought there are capture records for southern MOZ, and the middle of the Sahara according to fishbase

    [​IMG]
     
    Last edited: 11 Apr 2011
  13. 459b

    459b Thread Starter Moderator MASA Contributor

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    that i did not kow.
     
  14. richardmatlock

    richardmatlock

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    Rare reef fish in SA are my specialty.... though he is probably talking about the Ctenochaetus surgeons....
     
    Last edited: 11 Apr 2011
  15. AfricaOffroad

    AfricaOffroad

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    You guys aren't good at getting my jokes:p
    The situation described was me with my bucket of yellow zebrazoma releasing them into the warm waters of the KZN north coast.
    Getting bust in the process of release by the Parks Board.

    "These are yellow pyroferus juveniles, Warrant Officer Mullet Sir"
    ;)
     
  16. Nemos Janitor

    Nemos Janitor

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    Well it would seam some MASA members are not the only ones concerned about the coming regulation.

    If we are going to Shark dive, big game fish, spero, reef keep etc we need to take responsibility for our choices. We need to set examples and put forward a code of ethics in our sector.

    We need to form a body.?????

    Read the synergy..... then ponder our future.
    http://www.africandiver.com/index.php?option=com_lyftenbloggie&view=entry&year=2010&month=11&day=23&id=14%3Aopen-letter-to-the-sa-shark-dive-industry-re-best-practice-&Itemid=56


    As the author says. "BEST PRACTICE"
     
    Last edited: 16 Apr 2011
  17. seank

    seank

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    I was at a game reserve when I read this, and could not comment. Pity you edited the thread in the time gone by, as I was the reefer you referred to wrt Sewage etc.

    Yes, I still stand by my point, and yes, I would still release the fish in my tank back into the ocean once they become too big. But as Richard, I also only have locally caught fish in my tank, I do not even have bought live rock in my tank. So yes, if parasites came into my tank by using nsw locally collected, plants locally collected and fish locally collected, then surely the same parasite would go back to the local waters, or is there something I am missing here.

    My original statement below in blue as to your original referral before editing the post.



     
  18. 459b

    459b Thread Starter Moderator MASA Contributor

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    Not sure why i edited that out..think imay have been corecting spelling and got a bit carried away.

    THis was not an attack on anyone or pointing fingers. The idea of this thread was to highlight the fac that fish cannot be reintroduced into the ocean.

    If you read the post again, i said that fish introduced into a tank that has any non-native livestock cannot be thrown back in the sea. A tank that is made up of only locally caught species and no imported liverock is a different story.

    Regarding sewerage etc, i also said that that is a discussion for another thread. This thread is about the dangers of parasites and not about all the other negative things done to our oceans. The effects of sewerge/chemicals are completly different to the effects of parasites so therefore must be veiwed and handled as a separate topic and the one should not be oversahdowed or downplayed by the other.
     
  19. fishguy

    fishguy

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    I agree with everything Dave said!!! Wow my bff wot a guru!!! :lol:
     
  20. seank

    seank

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    Agreed Dave, only highlighting the other "culprits" too, as well as "explaining" my viewpoint. It is really not an attack towards you or anyone else for that matter. But yeah, understood about the dangers of other fish stocks
     
  21. durleo

    durleo

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    So Guys - We are so caught up with releasing a pathogen in the water - Ships do it all the time - They carry organisms in their ballast water and deposit it in the harbour or area they dock . Im not too sure what effect it has but carte blanche did a story a few years back where near a particular harbour the creatures situated there had built up a healthy population and where not local.
     
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