Caitriona Murtagh, The Cairns Post 3 Jun 08;
THE Great Barrier Reef could become a slime-filled dead zone brimming with algae and jellyfish unless commercial fishing is stopped, a Canberra academic claims.
Australian National University’s Professor Roger Bradbury has warned that fishing of large marine species removes an important ecological check on jellyfish and algae, which could then take over oceans and reefs.
As stocks of larger fish are depleted, smaller species thrive and the ocean may "flip" into a state where coral is replaced by slime, Professor Bradbury told The Cairns Post.
"You get an ocean that’s like swarms of jellyfish, blooms of algae," he said. "It’s really desperate. You’re recreating a prehistoric ocean. It’s like the ocean before fish.
"And by taking large fish out of the Great Barrier Reef, you’re risking this."
The Adriatic and Black Seas had already experienced flips where slime dominated the ocean, Professor Bradbury said.
And unless commercial sea fishing was stopped, the Great Barrier Reef Marine Park could face the same fate, he warned.
Dugong, turtle, dolphin, whale, tuna and mackerel numbers on the reef had been "so reduced they can’t do their job any more," he said.
Although protection mechanisms meant the Great Barrier Reef was better preserved than other coral systems, Professor Bradbury warned: "It’s still hammered by over fishing."
An immediate move to phase out commercial sea fishing could help brace the Reef against the coming impacts of climate change and ocean acidification, he said.
"By and large, you’ve got to start thinking about closing down commercial fishing on the Great Barrier Reef."
Great Barrier Reef Marine Park Authority chairman Professor Russell Reichelt said Professor Bradbury’s scenario described "the extreme case and the end point of extreme
over fishing".
"There are very tight controls and we’re nowhere near the limits Roger is warning us about," he said. "But I agree, we can’t be complacent."
Queensland Seafood Industry Association President Neil Green said Queensland waters could not be compared to Third World fisheries with unsustainable fishing practices.
"In other parts of the world we’ve got people using arsenic and dynamite to harvest, of course they’re going to get slime and jelly fish.
"I’m very confident that we’re not going to have these sorts of problems in Queensland."
