Just as the 1960s "green revolution" boosted agricultural yields worldwide, fish farming is experiencing a "blue revolution," with production of fish for human consumption doubling in the last 15 years, writes Mieke H. Bomann for the American News Service. But a new study published in the journal Nature shows that one of aquaculture's greatest promises -- to alleviate pressure on declining wild stocks -- is already broken. "More than 220 different species, from carp to sea bass to grouper, are now farmed around the world and account for 25 percent of fish eaten by humans. The practice has helped to lessen the demand for wild fish, many of whose numbers are in serious decline," Bomann says. "But raising some types of seafood in coastal beds and cages contributes to the decline in wild fish stocks rather than offsetting their falling numbers," because their high-protien diet-mostly fish meal and fish oil-is harvested from wild species.