Faced with declining fish stocks, managers have been forced to limit commercial fishing strictly in some waters, including the Grand Banks off Newfoundland, to prevent total collapse. But a new analysis  of global fish catches over the past 5 decades, to appear in tomorrow's issue of Science, suggests that even more drastic action is urgently needed.
To test the state of the ocean, researchers at the University of British Columbia, Vancouver, and the International Center for Living Aquatic Resources Management in Makati, Philippines, assigned each major food fish a "trophic level," depending on how high it is on the food chain. To track the trophic levels over time, the team analyzed fisheries catch data collected between 1950 and 1994 by the U.N. Food and Agriculture Organization (FAO). They found that there has been a gradual depletion of long-lived, high-trophic-level fish, such as cod and haddock, and a corresponding rise of low-trophic-level invertebrates and plankton-feeding fish, such as anchovy. The results suggest a marked decline in the quality of the fish catch. In the Black Sea, for instance, "there's been a huge increase in jellyfish as their economically valuable competitors have been removed," says University of British Columbia researcher Daniel Pauly.
The solution to this problem may lie in part in creating more zones off limits to fishing, Pauly says. "At the very least," adds marine researcher Elliott Norse, president of the Marine Conservation Biology Institute in Redmond, Washington, such zones "can offer quick and simple protection while complex, long-term, sustainable fishing policies are developed." But time is short, Pauly urges: "If things go unchecked, we might end up with a marine junkyard dominated by plankton."