Down Under, Fish Numbers Climb Up

23 June 2008 (All day)

CSIRO; (reef inset) NASA

Survivor. The Great Barrier Reef's coral trout has seen a spike in its numbers since a fishing ban went into effect.

In a time when positive news for the planet is rare, scientists announced today some promising ecological findings from Australia. The coral trout, a key fish species in the Great Barrier Reef, has made a stunningly rapid comeback--a turnaround the researchers credit to a sweeping conservation policy that banned all fishing in protected areas. As a keystone species of coral reefs, the trout's return could signal the improving health of the entire ecosystem.

In 2004, the Australian government designated a network of no-take zones--areas where all forms of fishing are prohibited--in the Great Barrier Reef Marine Park. The park, spanning 344,400 square kilometers and recognized as an international icon of natural beauty, houses the world’s largest collection of coral reefs and supports abundant diversity and many endangered species. The no-take zones encompassed 33% of the park's area--a controversial move that was sparked by a growing concern over the health of the region. This sweeping approach to conservation was the first of its kind--such a large-scale ban on fishing was unprecedented--but were these efforts worth the trouble?

To find out, fisheries biologist Garry Russ of James Cook University in Queensland, Australia, and colleagues compared fish populations right before and 2 years after the fishing ban was established. They surveyed 46 no-take preserves and 46 preserves where fishing was still allowed. Of the organisms surveyed, the coral trout staged the strongest comeback in the no-take marine preserves. The fish's numbers increased by 31% to 68% in the span of only 1.5 to 2 years, the team reports in Current Biology. What's more, the boost in coral trout numbers was widespread, occurring wherever a no-take preserve had been established. "I was personally stunned by the sheer scale of the positive response" to the ban, says Russ.

Although coral trout are the only species to have bounced back definitely, the researchers believe it could be a good sign for marine conservation. "Our findings show that large-scale reserve networks, set up to protect biodiversity and ecosystems, can produce rapid positive responses for targeted species," says Russ. "It is an important lesson for the entire world."

Tropical ecologist Leanne Fernandes, director of Earth to Ocean, a marine resource management consulting firm in North Queensland, Australia, agrees that the study is encouraging, but she says that no-take areas are only part of the solution. "The risk is that this may not be adequate, in the long run, to sustain the ecosystem as a whole," says Fernandes, who notes that pollution, climate change, and water quality can also drive down fish numbers. Marine ecologist Stephen Palumbi of Stanford University in Palo Alto, California, praises the scope of the research. "It's like the Hubble telescope for coral science," he says, "and this study is the first snapshot from this telescope."

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