The aftermath of the Australian WSSV. What now for prawn farmers?

Some of the standard mitigation strategies have been deployed, but what are the risks, and could we consider other strategies?

For example, commercial and recreational fishers have been discouraged to operate in the affected areas. Without the fishing pressures, crustacean numbers may rise, and the higher numbers of animals susceptible in the region could help sustain the disease. Is it possible to encourage over-fishing and no-size limit, to help reduce populations such that the disease cannot spread?

Surveillance is ongoing in the Logan River, through to Moreton Bay and the Brisbane River to determine the scale of the disease spread in the marine environment. Could these equipment and vessels used by personnel help spread the disease further?

Could they use the new technology called eDNA to help with their surveillance work – whereby water samples are taken for testing, instead of needing to catch the prawn/crab/polychaete to do the test.

There is no formal cost sharing arrangement in place among the Commonwealth and State Governments, or with industry (as there is with more established terrestrial farmed animals). This is space for development. So in the meantime, if a prawn farmer suspects WSSV, will they have the incentive to report it, or go into emergency harvest to salvage their investment? Though, the disincentive is that it would ve illegal not to report a notifiable disease to authorities.

I envisage that the 7 or more affected prawn farms would be looking towards culture of non-susceptible species. Perhaps barramundi, silver perch, cobia, grouper, goldfish, and dare I say, carp and tilapia! Algae could also be a thing. And then potentially return to farming prawns in the future.

Those businesses that choose to be among the first to restart prawn farming in the area earliest, risk generating a large biomass of susceptible animals that could potentially amplify what virus is there, and set back the eradication attempt.

With any disease, especially waterborne-viral diseases, it is very difficult to eradicate from a system; especially with prawn farming being a semi-open farming system. At the end of the day, Australia may need to accept that the White spot syndrome virus is endemic. Prawn farming practices will have to change. This means that prawn farmers will need to turn to people with such disease experience, to share their know-how on shrimp farming.

We have a naturalised Australian team member, who trained as a veterinarian in Brazil, worked in the largest prawn hatchery in Brazil (Aquatec), completed a Masters on prawn diseases caused by intracellular bacteria (NHPB), and a PhD on eDNA technology. The best thing is that our team member is based close to Brisbane, where all the WSSV activity is at.

Call us now, on how we can give your prawn farm the edge!

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Yours sincerely,

Dr Richmond Loh DipProjMgt, BSc, BVMS, MPhil (Pathology), MANZCVS (Aquatics & Pathobiology), CertAqV, CMAVA, NATA Signatory.
Aquatic Veterinarian & Veterinary Pathologist

THE FISH VET, AUSTRALIA – PERTH | SYDNEY | MELBOURNE | TOWNSVILLE | BRIBIE ISLAND

Mobile Aquatic Veterinary Medical & Diagnostic Services.

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• President WAVMA 2014
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