Thanks guys....some great valid comments that fall in line with the general consensus with the brethren down here....one in particular..from a Victorian carper....
They seem to believe that the killing of 95% of carp will bring their waterways back to a pristine condition, ignoring the fact that most of the damage is done by humans. Remove the industrial pollution, urban and farming run off, bank erosion from cattle and ski boats, habitat removal, redirection of waterways and reduction of natural flows and then you can blame the carp.
Take care
Paul