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Biodiversity study rattles buyers, fisheries managers

- Steven Hedlund
December 01, 2006

U.S. and international officials are dismissing the findings of a study published in the Nov. 3 issue of the journal Science that projects the world's commercial fisheries will collapse by 2048 unless biodiversity preservation and ecosystem management improves.

The four-year study claims the loss of biodiversity due to overfishing, pollution and climate change is "profoundly" reducing the abilities of the oceans to produce seafood and of marine populations to recover from adversity. Titled "Impact of Biodiversity Loss on Ocean Ecosystem Services," the study is the first to analyze all existing data on fisheries and ecosystems worldwide, claim its U.S. and Canadian authors.

"Basically, we found that the productivity of an ecosystem … declines when species are lost," says lead author Boris Worm, assistant professor of marine biology at Dalhousie University in Halifax, Nova Scotia.

Worm correlates the productivity of an ecosystem without all of its species to a car functioning with missing parts.

"If you throw out the gas pedal and steering wheel, the car doesn't run," says Worm. He was surprised but pleased the study received a lot of media attention because "it shows people care so much about seafood and the oceans."

But the study touched a nerve with seafood professionals, who were asked by family and friends if they were going to have jobs in 2048. They're also concerned that the Science study will overshadow the Institute of Medicine and Harvard School of Public Health studies released 
in October, which touted the health benefits of 
eating a variety of seafood twice a week, and scare consumers away from eating seafood.

"We don't want people to not eat seafood because they think the world is going to hell in a hand basket," says Steve Murawski, chief scientist of the National Marine Fisheries Service in Silver Spring, Md. He says the study is flawed because it uses catch data instead of biomass data, and catch data is "rarely" an accurate indication of a marine population's health.

"This doomsday scenario certainly doesn't gibe with what we've observed in 
the United States," says Murawski.

According to NMFS' annual report on the status of U.S. fisheries released in June, 74 percent of the 206 stocks and multi-species groups were not overfished (i.e. the stock's population is above the target for sustainability) in 2005, up from 72 percent in 2004, while 81 percent of the 237 stocks were not subject to overfishing (i.e. the catch 
is below the target set in 
the fishery's management plan) in 2005, the same as in 2004.

"In stating that all exploited [species] will collapse by 2048, the authors made a simple extrapolation of their results across the next 40 years. This is statistically dangerous," says Serge Garcia, director of the Food and Agriculture Organization's fishery resources division.

"This extrapolation relies on a business-as-usual forecast scenario," he explains. "For such a massive collapse to happen, it would require reckless behavior by all industries and governments over the next four decades, not to mention the economic forces that would discourage this from happening."

Global seafood consumption is projected to reach 180 million metric tons by 2030, says Garcia. Wild fisheries are expected to continue to yield about 90 million metric tons a year. Aquaculture is expected to fill the void, with production doubling to 90 million metric tons a year by 2030.

Worm says he's "convinced" the world's commercial fisheries will not collapse by 2048.

"It's not too late to turn it around," he says, "and we will."

Worm points to Alaska and Iceland as examples of areas where fisheries and ecosystems are well managed. But he says poorly managed fisheries still outnumber well managed fisheries worldwide.

The Science study was funded by the National Science Foundation, University of California and UC Santa Barbara.

- Steven Hedlund

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