A new study shows that the oceans' fish are being depleted so fast that eating seafood might be just a memory in 40 years.  The researchers say more is at stake than our diet, for they find the dwindling of fish stocks hurts the world economically and the ocean environmentally.  Researchers say it is not too late to reverse the trend.

A team of North American and European marine biologists and economists reports that our taste for fish has caused some ocean species to disappear since the 1800s, a trend that has accelerated in recent years.

The lead researcher, Canadian Boris Worm of Dalhousie University in Halifax, Nova Scotia says that roughly one-third of seafood species have collapsed so far. That means their catch has declined 90 percent below the historic maximum. Of these sea species, seven percent have become extinct.

"If this trend continues, if we don't change the way we are managing ocean ecosystems, this trend projects that 100 percent of species will collapse by the year 2048 or around that," he said.

Worm's team arrived at this conclusion after reviewing many studies that monitored the impact of species loss on smaller, local scales and by checking historical archives to track changes in species diversity over the past one-thousand years in 12 coastal regions around the world. They also compiled seafood catch data from 64 large ocean fisheries and analyzed fisheries databases compiled by the United Nations and the University of British Columbia.

The international managing editor of the journal Science that published the study, Andrew Sugden in London, says the findings reveal planet-wide trends that mirror what scientists have found at smaller scales.

"I think the strength of this work lies in the breadth in the array of information that the authors have used for their analysis," he noted.  "This analysis is global in scope."

From all the data, Worm's group found that not only are fisheries affected by the species decline, but so is the oceans' overall health.

"There was a decrease in water quality," added Mr. Worm.  "For example, harmful algae blooms shot up by 450 percent, oxygen depleted areas increased by more than 300 percent, and so on.  So there were negative consequences in the coastal environment that were felt by the humans who were living nearby."

The researchers say many of the economic activities along coasts rely on diverse systems and the healthy waters they supply. When they examined marine areas that had been restored, protected locations such as reserves and those closed to fishing, they found that fish catches increased substantially and the waters were much less susceptible to human and environmental disturbances.

"There are signs people are trying to turn this around and that it's not too late to turn this around," he explained.  "We can do this, we know how to do this, and it can be done, but it must be done soon."

A conservationist at the Monterey Bay Aquarium in California who was not involved in the study, George Leonard, says safeguarding the seafood supply will require finding new ways to restore healthy fisheries.

"If we are going to continue to eat seafood, we're going to have to work darn hard to be sure that there are enough fish in the sea to consume," he said.  "That is, fisheries management is going to have to work hard to ensure sustainable fisheries."