Boris Worm of Canada Dalhousie University believes there is still hope for global stocks to recover. (Photo: N. Pearce, Dalhousie University/T. Engoe)

World's fisheries at risk of collapse, but recovery is possible: study

WORLDWIDE
Friday, July 31, 2009, 23:50 (GMT + 9)

The world's fisheries are at risk of collapse, but recovery is possible if governments act to manage commercial fishing, a comprehensive study published Thursday has found.

Several regions in the United States, Iceland and New Zealand have made significant progress in rebuilding stocks devastated by decades of overfishing through careful management strategies.

But the study, published in the journal Science, found that 63 per cent of assessed fish stocks worldwide require rebuilding to reverse the collapse of vulnerable species.

"Across all regions, we are still seeing a troubling trend of increasing stock collapse," said lead author Boris Worm of Canada's Dalhousie University.

"But this paper shows that our oceans are not a lost cause."

Half of the 10 regions examined had managed to decrease their exploitation rate (the proportion of the total fish population that is caught) -- the primary driver of depletion of collapse.

"This means that management in those areas is setting the stage for ecological and economic recovery," Worm said. "It's only a start -- but it gives me hope that we have the ability to bring overfishing under control."

Worm cautioned that the analysis -- the most comprehensive to date -- was mostly confined to managed fisheries in developed countries where long-term data on fish abundance is collected.

The threat of collapse could thus be even higher in the remaining 75 per cent of the world's fisheries.

The study found that a range of management strategies helped protect and restore fishing stocks.

Switching to nets that allow smaller fish to escape and closing some key areas to fishing helped Kenya increase the size and amount of fish available and boost fishing incomes.

In many areas, however, take rates will have to be cut in half in order to preserve fish stocks, Worm said in a conference call with reporters.

The study, which Science editor Andrew Sugden called an "important and convincing new analysis" and "a real step forward toward the goal of restoring fisheries" was published in a special issue dedicated to ecological restoration.

In a separate study, researchers found that ecological restoration on land can reverse some, but not all, of the environmental degradation caused by humans.

Spanish and British researchers analysed 89 assessments of restoration attempts in a wide range of ecosystems around the world.

They found that biodiversity had improved, on average, by 44 per cent while ecosystem services like carbon storage and soil and water management increased by 25 per cent.

"However, values of both remained lower (14 and 20 per cent respectively) in restored than in intact reference ecosystems," lead author Jose Rey Benayas of Spain's Alcala University wrote.

The "unprecedented" restoration of native oysters in Virginia was also documented by researchers who built oyster reefs in nine protected sanctuaries in the Great Wicomico River.

There were less than two oysters per square meter in the river when the reefs were built in 2004.

By 2007, the nine reefs housed 185 million oysters -- nearly as many as can be found in all the waters of neighbouring Maryland.

And the highest reefs housed over 1,000 oysters per square metres, nearly ten times typical densities on protected reefs in Chesapeake Bay.

"Similar approaches with other natural and artificial reefs could lead to recovery of the native oyster throughout North America, as well as other ecosystems worldwide where native oysters have been functionally extirpated," wrote lead author David Shulte of the Virginia Institute of Marine Science (VIMS).  

AFP

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