Streptococcus iniae was first characterized by Queensland Department of Primary Industries in 1994-5 in sea-caged barramundi, and I have been working with it since 1996. Losses, however, are not restricted to just the sea-cage barramundi, but also those growing in freshwater recirculating systems. Indeed, in the last year losses in the industry are much higher from freshwater farms. There is a recent article of mine published on this in Diseases of Aquatic Organisms 36(3) p177-181.
Since March 1999 I have been working with many other farms throughout Queensland, New South Wales and South Australia which have also had heavy losses to this disease, not restricted to barramundi but including Murray cod and silver perch. This disease has been diagnosed in Australia by at least 3 independent sources, including government departments. S. iniae was also mentioned in a technical issues paper on the importation of ornamental finfish into Australia (AQIS).
Furthermore, I have also obtained isolates, from pathology labs, of S. iniae from workers at 2 of the farms.
The fish kills in North Queensland were widely reported in the media, and were handled by a local Government department. Their results were inconclusive about the etiology of the disease, however, my research which was conducted 3 days earlier with moribund fish (not partially decomposed) indicated S. iniae was a high candidate for the outbreak (94% isolation from all animals tested). There was no link made between the disease at the farms and the wild outbreak. However recent research indicates many of the fish species found in local waterways carry the bacterium, most importantly the exotic Tilapia which is found in high numbers in the North.
S. iniae is here, not just in Queensland but throughout Australia, and it poses a high risk not just to aquaculture but to native fish species in the wild.
Mr Erin Bromage
Aquatic MicrobioBlogy and Pathobiology
Department of Microbiology and Immunology
James Cook University, Townsville, 4811