With a waterproof writing pad in hand and an air tank on his back, Jerry Ault dives into the clear blue waters off the Florida Keys.
The splash frenzies a swarm of barracudas encircling the biologist's diving platform a 100-foot research vessel. Dr. Ault sinks away from the boat, through the swarm's midst, joining other divers who are toting underwater digital video cameras to capture images of the numerous fish species living here.
This scene was repeated for 30 straight days recently, as Ault and 22 other scientists made 1,806 dives to conduct a "fish census" across the Florida Keys coral-reef system. The reef is a key nursery for more than 200 fish species, although overfishing, habitat degradation, and the area's growing population have made it an "ecosystem at risk."
A year after a controversial federal law put 151 square miles of water in and around Dry Tortugas National Park off limits to fishing, scientists found promising jumps in some exploited species but say it will take time for other key species to revive.
The success or failure of this marine sanctuary the largest of its kind in the US could determine whether other proposed no-take zones off America's coasts go forward.
Despite rises in some species, the fish census scientists found that snappers, groupers, and grunts are still prime victims of overfishing. And the numbers of mature fish, which have a greater ability to spawn, are falling.
Thus, they say, another generation may have to pass before the ecosystem revitalizes itself and fishers can once again tell true tall tales about their catches.
"As these areas begin to recover, we'll start to see more fish and bigger fish," says Steven Miller of the University of North Carolina's National Undersea Research Center. "We'll have an opportunity to see things the way they were 40 years ago."
Over the 3,100 square miles of ocean life studied, exploited fish species appeared to have a harder time in sites close to large human population centers. There, the number of fish was diminished, as was their size. In fact, Ault says he made 28 dives in Biscayne National Park, a heavily visited area, before spotting a legal-size snapper or grouper.
These larger fish sizes are the ones with the greatest potential to reproduce. A 10-year-old red snapper, for example, produces 9 million eggs in one spawning season. It takes more than 200 small fish to produce that same number.
"If we don't protect [bigger fish], we'll have a stunted population where the fish get smaller and smaller," says Dr. James Bohnsack of the National Oceanic and Atmospheric Administration's Southeast Fisheries Science Center. "A lobster will be the size of a shrimp, and that's not desirable from a fisherman's point of view."
Indeed, scientists say that the livelihoods of commercial fishers in the Sunshine State could be at stake if there aren't measures such as no-take zones to stimulate fish population growth.
True, a number of other regulations are already in place: These include catch quotas, equipment restrictions, and seasonal bans on fishing certain species.
Some fishers say these other methods are enough. They've spoken out against no-take zones, asserting they'll put a damper on business. Currently, the Keys support a multimillion-dollar fishing industry, which includes not only the commercial sector, but also a sizable number of recreational fishers.
Still, it may be too soon to measure the preserve's impact. Gregory DiDomenico, executive director of Monroe County Commercial Fishermen Inc., which represents 1,200 full-time fishers, notes that their work can be affected by a multitude of factors that are hard to distinguish.
"There's always some displacement of traditional fishing grounds," he says, "which of course is going to have an economic effect on us."
Mr. DiDomenico says he is not for or against no-take zones, but the organization does pay close attention to the issue of overfishing. "We hope the proposed benefits of no-take zones make their way to us."
As the scientists aboard the research vessel chatter excitedly about their front-row views of magnificent coral and exotic fish, the potential benefits of no-take zones seem a little closer to reality.
"This is the first time we've ever done a whole reef ecosystem at one time," says Ault, a University of Miami professor. With the sun beating down on the boat deck, he adds that their work is only beginning. "Documenting changes within reserves should provide better data and understanding of reserve impacts and, if successful, will provide support for similar efforts elsewhere."