Three years after a controversial paper predicted the collapse of 90% of the world's edible fish species by 2048, the original paper's author and a main opponent have collaborated on a groundbreaking survey of the Earth's oceans which finds hope for fish stocks and the millions who rely on them for protein — but only if overfishing is ended.
The paper, published today in the journal Science, comes after a 2006 Science paper by marine biologist Boris Worm of Dalhousie University in Canada and colleagues. Its prediction of the destruction of fish populations because of overfishing and ecosystem destruction caused enormous controversy among marine ecologists and fisheries biologists.
But a 2006 radio interview that brought Worm and fisheries biologist Ray Hilborn of the University of Washington in Seattle together to debate the paper led them to launch an international research effort over two years involving 21 scientists who surveyed 166 areas where specific fish species are caught — called a fishery worldwide and looked intensively at 10 marine ecosystems.
"It was like a 'CSI' for overfishing," says Worm.
What they found was that in areas where the rate of fishing is reduced, even collapsed fish stocks can revive and become commercially viable again.
"This has enormous practical application for the United States and world policy, with billions of dollars at stake," says Steve Murawski, chief scientist of the National Marine Fisheries Service.
The key to healing overfished marine populations, the scientists found, is to cut the number of fish taken to somewhat below what's long been considered the maximum sustainable yield.
"Unfortunately there's a significant period of low catches required to rebuild stocks to higher levels," but long term, most fisheries can rebound, says Hilborn.
The most effective ways to allow fish populations to recover include closing some areas to fishing to give stocks secure breeding areas, changing fishing gear so smaller and juvenile fish can slip through and establishing catch share programs that assign fishermen the right to harvest a certain amount of fish so there isn't the unbridledcompetition
Of the 10 areas intensively studied, the best managed were in the U.S., Iceland and New Zealand.
But 63% of the assessed fish stocks worldwide still need rebuilding, the researchers found.
A major problem is that many industrialized countires have protected their own fish stocks, but then send their fishing fleets to countries with weaker laws and enforcement capacity. This is especially a problem in Africa.
"In the United States, 83% of what we eat in seafood comes from overseas, in many cases from these countries that have a poor track record," says Murawski.