Barrier Reef 'no-take' zones see leap in fish numbers

Rachel Nowak,
NewScientist.com 23 Jun 08;

A controversial decision to halt commercial and recreational fishing across vast areas of the Great Barrier Reef has proven remarkably effective for reviving coral trout numbers.

"Everyone is a little surprised," admits Garry Russ, a marine biologist at James Cook University in Townsville.

"We've seen a consistent pattern of recovery of coral trout from just north of Cairns to as far south as Heron Island," he says. "It's an extraordinarily large area."

In mid 2004, the Australian government rezoned the Great Barrier Reef Marine Park to create the world's largest network of marine "no-take" zones.
No fishing

Fishing was totally banned across a third of the park – more that 100,000 km2 – including parts of 70 biologically distinct "bioregions".

At the time, surveys found that the majority of Australians wanted protection for the reef, but the move was also highly controversial among both commercial and recreational fishers who primarily target coral trout.

Surveys carried out by Russ's team now show that coral trout numbers have increased by over 60% in no-take areas around two groups of inshore islands – Palm Island and the Whitsundays – 18 months to two years after rezoning.

By contrast, Coral trout numbers in nearby fished areas did not change. "In the long term, the hope is that as numbers build up in protected areas, more fish will spawn successfully, enhancing numbers in fished areas," says Russ.
Full recovery

A second team led by Hugh Sweatman of the Australian Institute of Marine Science in Townsville, has also found that coral trout numbers had increased significantly in no-take zones around reefs from 32 to 200 kilometres off-shore.

In four of these offshore regions, numbers of coral trout were between 31 and 64% higher compared to unprotected regions nearby, just two years after the zoning took place.

The consistency of the results, combined with the finding that in-shore coral trout numbers did not decrease, suggests that the differences are indeed due to decreased fishing in the off-shore no-take zones, rather than increased fishing elsewhere, says Russ.

"It's a very positive start, but full recovery of coral trout will take 10 to 15 years of really effective protection," says Russ. The two teams are monitoring 160 different species of fish, but so far only numbers of coral trout have changed since the rezoning.

Journal reference: Current Biology (vol18, p 514)

Coral trout hooked on fishing ban
Dani Cooper, ABC 24 Jun 08;

Coral trout numbers on the Great Barrier Reef have bounced back in areas where fishing is banned, a new study shows.

Writing in today's Current Biology journal, researchers from James Cook University (JCU) and the Australian Institute of Marine Science (AIMS), say their study shows no-take marine reserves, in which fishing is completely banned, are effective in protecting exploited species.

Study author Professor Garry Russ, from the School of Marine and Tropical Biology at JCU, says the numbers of coral trout, a favoured target of commercial and recreational fisheries, bounced back in no-take reserves within two years or less of the area being rezoned.

On 1 July 2004 the Australian Government threw a protective net over the Great Barrier Reef by banning fishing in about a third of the marine park.
Worth the controversy

The move, which locked fishermen out of 100,000 square kilometres of the reef, created intense community debate with the Government offering compensation packages to those affected by the ban.

Russ says his study shows the controversial move was worth the pain.

He says the team has documented increases in coral trout density between 31% and 68% in two years or less.

"The big surprise was that we detected a consistent, rapid increase in multiple large reserves spread over 1000 kilometres offshore and 700 kilometres inshore," he says.

The team used an underwater visual census survey to monitor numbers in the new coral reef reserves and in control areas that remained open to fishing before the ban took effect and one and a half to two years after rezoning.
Significantly higher

They found that coral trout numbers were significantly higher in no-take reserves than in sites that remained open to fishing in four of five offshore regions and two of three inshore regions.

Russ says the figures are probably due to a decrease in fishing mortality inside the new reserves rather than an increase in fishing outside.

"Our results provide an encouraging message that bold political steps to protect biodiversity can produce rapid, positive results for exploited species at ecosystem scales," Russ says.

"It is an important lesson for the entire world."

Down Under, Fish Numbers Climb Up
Lauren Cahoon, ScienceNOW Daily News 23 Jun 08;

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."

Ban Spurs Dramatic Fish Recovery in Australia
Anne Minard, National Geographic News 24 Jun 08;

Australia's coral trout have thrived under a fishing ban on the Great Barrier Reef, showing that no-take reserves can spur dramatic comebacks in overfished ocean habitats, new research suggests.

But the bold move to ban fishing to save fish would be hard to replicate along most other coasts, said the Australian study's lead author.

Coral trout is the common name of about a half-dozen fish species from the grouper and cod family targeted by commercial and recreational hook-and-line fisheries in Australia.

Scientists behind the new study found that the fish bounced back within two years after no-take reserves were established.

Garry Russ, a marine biologist at James Cook University who led the research, said his team was "surprised" to find coral trout population increases of up to 68 percent in such a short period of time.

"This represents a positive and unprecedented response to reserve protection," he said.

The study appears in today's issue of the journal Current Biology.

Largest No-Fish Zone

Australia's Great Barrier Reef Marine Park generates about five and a half billion U.S. dollars annually from tourism and fisheries.

Four years ago the Australian government rezoned the park, placing nearly one-third of it into the world's largest network of no-take marine reserves. They cover more than 62,000 square miles (100,000 square kilometers).

To monitor the new reserves, researchers used underwater imaging techniques to survey coral reefs inside and outside protected areas, where fishing was still allowed.

The scientists found that coral trout numbers were significantly higher in no-take reserves than in sites that remained open to fishing.

Researchers say the increase is probably due to decreased fish mortality inside the new reserves, rather than increased fishing outside.

"Although preliminary, our results provide an encouraging message that bold political steps to protect biodiversity can produce rapid, positive results for exploited species at ecosystem scales," Russ said.

"No Surprise"

Enric Sala, a marine biologist at the Scripps Institution of Oceanography at the University of California in San Diego, said it's intuitive that a fishing ban would help fish survive.

"This rebound is great news, but it is not 'new' news," he said. "When you truly protect a species from fishing or create a no-take marine reserve, large fishes come back."

Sala notes that Florida jewfish and Mediterranean dusky grouper rebounded under similar conditions.

Study co-author Hugh Sweatman, a reef ecologist at the Australian Institute of Marine Science, agrees.

"My 10-year-old son saw the graphs and said, If you stop fishing, don't you expect to find more fish? And he is right," Sweatman said.

He noted that while individual reserves have resulted in quick increases of target species before, "what is new about our study is the rapid, fairly consistent effect in multiple reserves over a huge area."

The ecologist says the Great Barrier Reef fishing ban has offered a rare chance to test whether the largely theoretical idea of marine reserve networks actually works, adding that many questions remain.

Among them: the long-term effects of no-take reserves on coral trout populations, as well as other species on the Great Barrier Reef food chain.

Russ, the lead study author, is currently investigating whether juvenile coral trout from protected areas will migrate to help repopulate stocks in less-protected areas over time.

Bold Strategy

Sweatman says the bold strategy to protect coral trout in Australia would be hard to replicate elsewhere.

The Great Barrier Reef is "a large area with a small and relatively rich coastal human population that is not depending on the reefs for the next meal," he said.