In the most ambitious study of marine life ever undertaken in the United States, scientists spent a month recently counting the fish in the Florida Keys, from the waters south of Miami to the coral forests beyond Key West.
The fish census _ the first underwater survey encompassing the entire Florida Keys ecosystem at once _ is the most aggressive effort yet by scientists and wildlife officials in a campaign to save endangered fish stocks in South Florida and restore the shrinking Dry Tortugas, the largest living coral reef in North America.
As Florida's human population soared to more than 16-million in recent decades, the once-abundant stock of snapper, grouper and grunts has significantly declined because of recreational and commercial fishing. Researchers say that 70 percent of all fish species have been overharvested.
"This is what happens when you have 900,000 fishing boats and people who feel that it is their God-given right to go out and catch 'fish," said James Bohnsack, a marine biologist with the National Oceanic and Atmospheric Administration.
The problem is not unique to Florida. Historically considered an unlimited food source, fish populations have diminished around the globe, threatening not only natural marine habitats but also the economies of coastal areas that rely heavily on commercial fishing.
A study published last year in the British journal Nature found that the worldwide catch has declined by 360,000 tons since 1988.
According to the United Nations, 70 percent of marine fisheries worldwide are fully used, overfished or depleted, and 13 of the world's 15 major fishing areas are fished at or beyond capacity.
During the census, scientists from the University of Miami and the NOAA sampled 200 species of fish in a 3,100-square-mile patch of reef from Key Biscayne to Dry Tortugas National Park to form a snapshot of the entire ecosystem.
Using high-tech video equipment, a measuring stick, plastic paper and underwater pencils, they dived into the waters from a 100-foot boat and counted the fish one by one and checked lengths. Results of the 30-day census that ended in June will be used to evaluate the effectiveness of existing state and federal conservation policies and to help establish new guidelines, including the use of no-fishing zones _ the most controversial tool in fishery management.
In an experiment to determine if untouched fish populations could thrive again, the federal government last year declared 151 square miles of waters in and around the Dry Tortugas off limits to all fishing. In 1997, the Florida Keys National Marine Sanctuary established 23 small "no-take" zones around popular, much smaller, coral reefs.
Other no-take zones are being considered, though recreational and commercial fishing groups have opposed them, claiming that most regulations are not enforced and that researchers exaggerated the decline in fish and downplayed the impact of pollution and coastal development.
The no-take zone is particularly important to the future of Florida's coral reef, which drapes the coast for 130 miles from Key Biscayne to the Dry Tortugas. Worldwide, the ancient, slow-growing reefs have been imperiled by everything from global warming to boat anchors and snorkelers to pollution.
Along the Florida Keys, the Dry Tortugas plays an invaluable role in the marine ecosystem, harboring some 200 species of marine life that rely on it for food, shelter and protection. The reef also serves as a nesting ground for fish eggs and larvae that eventually populate the fish habitat throughout the coast.
In the protected areas, researchers are already seeing signs of progress. Larger fish are more prevalent in those zones. The Goliath grouper that was near extinction a decade ago is making a comeback. The fish can grow to 800 pounds, but it takes decades for them one to fully mature. The key to the their fish's survival is managing their environment, officials said.
"We haven't had a problem telling people they can't hunt for buffalo in Yellowstone National Park. But we've had a hard time telling them they can't fish for grouper in the Dry Tortugas," said John Hunt, research administrator for the Florida Marine Research Institute.
"Now we are saying you can look at them, but you can't catch them," he said. "In the long- run, there will be an abundance of big fish available. But it's not easy to convince people it's in their best interest to wait."