A taskforce responding to what could be the world's worst outbreak of blue-green algae, in southern Queensland, has been told there is no way to stop the current bloom.

It is now covering nearly 40 square kilometres in Moreton Bay,prompting the taskforce to issue a public health warning.

Bill Dennison from the University of Queensland's Botany Department says the problem will get worse.

"During this bloom, I don't see a whole lot of potential for stopping the existing spread," Dr Dennison said.

"It's happened so fast and it's a real difficult problem logistically to deal with the hundred to thousands of tonnes of lyngbya we have in the bay currently."

Queensland Department of Primary Industries fisheries manager Mike Dredge says the bloom is stopping some commercial fishermen from earning their living.

"We've got pretty clear evidence that in localised areas, the presence of lynbya is severely affecting commercial fishing operations, both by fish avoiding in some areas and also by the physical inability of fishermen to actually work their nets in the areas where it occurs," he said.

"This is not just in Moreton Bay, it also occurs in Hervey Bay." http://www.abc.net.au/news/science/environment/2000/04/item20000406064908_1.htm