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Thread: KHV in Australia - the sky will be falling

  1. #1
    Oyagoi mrbradleybradley's Avatar
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    KHV in Australia - the sky will be falling

    https://blog.csiro.au/reclaiming-our...om-feral-carp/

    Imagine the population explosion of other bacterial and parasitic pathogens living happily on tons of sick carp, followed by tons of dead carp. Australia's native fish are at risk to suffer from from an outbreak of any number of other diseases as a result................................

  2. #2
    Daihonmei MikeM's Avatar
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    Naturally, I look at this from a hobbyist's perspective that KHV should be eradicated, not spread.

    I readily understand the environmental negatives of introduced species. We have a full share of naturalized exotics in Florida, from pythons in the everglades to iguanas ravishing bird colonies' eggs, to plecostomus in our springs and a weevil destroying native bromeliad species. I am doubtful introduction of a viral pathogen is very smart. Virus has a way of mutating to find more hosts. I am also doubtful about the effectiveness of the virus to accomplish the goal. KHV has been found in many waterbodies in the U.S., with occasional mass die-offs. But, the Asian Carp that have caused havoc in the Mississippi River basin are still doing so. I notice that there is no mention of what impacts there have been on carp populations in natural systems where KHV is present. Rather than studying the effects on mice and such in laboratories, field studies where KHV is present would be the most helpful. I think the finding would be that despite mass deaths randomly popping up, the overall impact is not much. It only takes a few carriers with their millions of eggs to replace the losses. Of course, given the status of koi down under, there is no official concern that the random outbreaks may include hobbyists' ponds.

    It has seemed to me that the best solution for the Mississippi River basin is to create an economic resource out of the carp. They may not be desired for consumption locally, but it seems to me that they would make as good a source for fishmeal as some of the marine species used now. The economics of efficient capture is where I would focus attention.

  3. #3
    Sansai
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    Murray-Darling Basin, Australia.

    If their are so many and so big, what do they live off?

    Introduce some crocodiles,

    or find a greedy entrepreneur,he will take care of them. Maybe stuff something else up in the process.

    I do not believe the Aussies have the balls to go through with KHV!

    Garfield

  4. #4
    Daihonmei MikeM's Avatar
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    In regard to carp developing resistance, I cannot find a study I read some time ago. I did come across a reference to a similar study in a manual for diagnosing various fish diseases:

    "2.4.4. Resistance breeding
    Differential resistance to KHVD has been shown among different carp strains. The progeny of crosses of two strains of domesticated carp and one strain of wild carp were challenged by experimental or natural infection. The lowest survival rate was approximately 8%, but the survival rate of the most resistant strain was 61–64% (Shapira et al., 2005). In a more recent resistance study, 96 families derived from di-allele crossing of four European/Asian strains of common carp were experimentally challenged with KHV. Survival rates of the five most resistant crosses in the final virus challenge trial ranged from 42.9 to 53.4% (Dixon et al., 2009)."

    That is, when KHV survivors spawn, their offspring have much increased resistance. One can readily imagine that after a few generations, KHV is no longer a threat to the population. The purposeful release of KHV could give a quick reduction in the population, but will cease to be very effective when the population rebounds. The eradication/control goal is not accomplished, but the virus is permanently part of the eco-system.

  5. #5
    Daihonmei MikeM's Avatar
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    And, this abstract shows that carp are thriving in at least some U.S. locations despite carrying the virus:

    "Analysis of koi herpesvirus latency in wild common carp and ornamental koi in Oregon, USA.
    J Virol Methods. 2013; 187(2):372-9 (ISSN: 1879-0984)

    Xu JR; Bently J; Beck L; Reed A; Miller-Morgan T; Heidel JR; Kent ML; Rockey DD; Jin L
    Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, United States.

    Koi herpesvirus (KHV) infection is associated with high mortalities in both common carp (Cyprinus carpio carpio) and koi carp (Cyprinus carpio koi) worldwide. Although acute infection has been reported in both domestic and wild common carp, the status of KHV latent infection is largely unknown in wild common carp. To investigate whether KHV latency is present in wild common carp, the distribution of KHV latent infection was investigated in two geographically distinct populations of wild common carp in Oregon, as well as in koi from an Oregon-based commercial supplier. Latent KHV infection was demonstrated in white blood cells from each of these populations. Although KHV isolated from acute infections has two distinct genetic groups, Asian and European, KHV detected in wild carp has not been genetically characterized. DNA sequences from ORF 25 to 26 that are unique between Asian and European were investigated in this study. KHV from captive koi and some wild common carp were found to have ORF-25-26 sequences similar to KHV-J (Asian), while the majority of KHV DNA detected in wild common carp has similarity to KHV-U/-I (European). In addition, DNA sequences from IL-10, and TNFR were sequenced and compared with no differences found, which suggests immune suppressor genes of KHV are conserved between KHV in wild common carp and koi, and is consistent with KHV-U, -I, -J."

    KHV has spread all over the U.S., but has not eradicated carp from our lakes and rivers. Our koi remain susceptible because they are kept as isolated from KHV as commercial practice permits.

  6. #6
    Jumbo Appliance Guy's Avatar
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    Quote Originally Posted by MikeM View Post
    In regard to carp developing resistance, I cannot find a study I read some time ago. I did come across a reference to a similar study in a manual for diagnosing various fish diseases:

    "2.4.4. Resistance breeding
    Differential resistance to KHVD has been shown among different carp strains. The progeny of crosses of two strains of domesticated carp and one strain of wild carp were challenged by experimental or natural infection. The lowest survival rate was approximately 8%, but the survival rate of the most resistant strain was 61–64% (Shapira et al., 2005). In a more recent resistance study, 96 families derived from di-allele crossing of four European/Asian strains of common carp were experimentally challenged with KHV. Survival rates of the five most resistant crosses in the final virus challenge trial ranged from 42.9 to 53.4% (Dixon et al., 2009)."

    That is, when KHV survivors spawn, their offspring have much increased resistance. One can readily imagine that after a few generations, KHV is no longer a threat to the population. The purposeful release of KHV could give a quick reduction in the population, but will cease to be very effective when the population rebounds. The eradication/control goal is not accomplished, but the virus is permanently part of the eco-system.
    Wouldn't this be applicable to koi as well?

  7. #7
    Oyagoi mrbradleybradley's Avatar
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    KHV : Summary of Some Key Concerns on the planned to release this virus in order to control feral carp in Ausralia

    KHV is a virus that results in 80-100% mortality in carp and koi. There is no vaccine available.
    Koi are our family pets and little consideration has been given to the welfare of the koi. Nor has there been consideration on the financial, emotion loss or wellbeing of their owners.
    The use of the virus in the Australian environment is likely to result in the death of massive numbers of feral carp, resulting in a detrimental effect on the environment, including reduced oxygen. This and the stressed, sick carp is likely to cause poor water quality, that may kill native fish.
    Stressed, sick and dead carp may increase the populations of other disease causing pathogens within the environment.
    There is currently no plan in place to manage the environmental impact of tons of dead carp.
    The impact of KHV on non-target species, including all native fish and amphibian has not been thoroughly studied.
    The impact of KHV on Australian Koi and the hobby has not been studied.
    The impact of KHV on Australian Goldfish (shown overseas to be carriers of the virus) or on Butterfly and Longfin Koi has not been studied.
    Concerns exist that the virus may change and mutate. There is no guarantee on how this will impact other native fish, amphibian, the platypus, bird life or any other animal.
    Once released, there is no way of controlling it. There is no plan in place to prevent the spread or the distribution of the virus by birds collecting sick fish.
    Nor is there a plan in place to control the accidental or deliberate relocation of affected carp by anglers.
    The impact of the general public witnessing the suffocating death of tons of carp has not been addressed.
    The koi hobby and industry has not been adequately consulted on the KHV release. It was only in late that the NSW DPI met formally with the koi clubs of Australia, despite requests prior. The plan for the release has been in place for nearly 10 years. The Koi hobby and industries have not been given time to be truly informed in the decision making process, nor given time for planning.
    Alternatives to the release of KHV have not been adequately explored, including the use of the “Daughterless Carp” project, or the harvesting of carp for commercial use.

    What can you do?
    Soon, the Australian Koi hobby will publish a form letter, for use by everyone, to send to the appropriate government people, along with who to send them to. Further, all members of the koi hobby will be asked to participate in an Economic Study, to gauge the financial impact of the release.
    Further updates will be posted over the next few weeks and months ahead.

  8. #8
    Oyagoi yerrag's Avatar
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    This is terrible public policy. Guess the Aussie government has an out-of-touch bureaucracy. It is doing something for the sake of appearing to do something. The solution creates a larger problem, but since that larger problem is not considered a certainty by them, they would rather cross their fingers. Such chutzpah and bravado, they will cross the bridge when they get there.

    Unfortunate the world is full of non-native species because of man's mobility and penchant for exotics. It is not going to stop, even with laws controlling the border entry of plants and animals. Solutions exist, even if they have not been discovered. But a half-baked solution with far-reaching unintended consequences by bureaucrats is unfortunate. There won't be environmental refugees, those affected just die and balance is forever altered. The world will just cope.

  9. #9
    Daihonmei MikeM's Avatar
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    Quote Originally Posted by Appliance Guy View Post
    Wouldn't this be applicable to koi as well?
    Eventually, if all exposed were not euthanized, I think resistance would occur. However, in the meantime, all the breeders and hobbyists would have to get through the mass die-offs and hope some good genetics survive to re-build a breeding base. I doubt many breeders could survive a period of years of mass die-offs, nor that their customers would continue purchasing. For the hobby to continue, there would have to be acceptance that for some number of years a percentage of all koi would die from a lack of resistance. It would be several generations before some sort of universal resistance would appear. Meanwhile, a 10-20% die-off factor in Nature would not impact the ability of carp to thrive as a population, but it could affect hobbyists' willingness to spend anything on koi. It takes the folks who spend the big bucks on a fish to keep everything progressing.

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