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Long-term artificial reef project may break grouper ‘bottleneck,’ UF researcher says

By:
Mickie Anderson (352) 392-0400

Source(s):
Bill Lindberg wjl@ufl.edu, 352-392-9617
Jon Dodrill jon.dodrill@myfwc.com, 850-922-4340

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GAINESVILLE, Fla. — One of the country’s biggest and longest-running artificial reef research projects is about to widen its scope, and the payoff could be healthier grouper in the Gulf of Mexico, a University of Florida researcher says.

Over the last 17 years, UF researchers have built and placed a 26-mile line of artificial reefs in the Gulf and studied its impact on gag grouper, a popular game and food fish.

The reefs give shelter that researchers believe helps young gag grouper grow to adulthood and replenish heavily harvested populations.

Bill Lindberg, an associate professor with UF’s Institute of Food and Agricultural Sciences who leads the project, recently learned its funding has been extended for a second phase that will cost about $1 million over the next four years.

Not all the funding is secure, though the research is expected to span the next decade.

There are many reasons for such a massive project. Because artificial reef building is often publicly funded, there is interest in knowing how to best use artificial reefs. And knowing how fish use the reefs is key to helping manage fish populations.

There is public interest in knowing how to best use artificial reefs. And knowing how fish use them is key to helping them.

Jon Dodrill, a Florida Fish and Wildlife Conservation Commission environmental administrator, calls the project significant.

“Just in the sheer number of years involved in the planning process and looking ahead at continued monitoring, continued construction…it’s one of the largest artificial reef projects that’s been undertaken,” he said.

Gag grouper is a vital Florida fish, popular with recreational and commercial fishermen and a staple for hungry tourists and natives.

“What restaurant doesn’t have a grouper sandwich on its menu?” Lindberg said.

But scientists who assessed the gag grouper population last year say the species has been fished too heavily. In 2004, West Florida fishermen hauled in 7.5 million pounds of gag grouper—up from less than 2 million in 1987.

And federal rules say steps must be taken to curb overfishing in the next two years. On the Atlantic coast, that could mean up to a 60 percent reduction in gag grouper landings. Officials will call for Gulf gag grouper harvest reductions as well, but numbers aren’t yet firm.

Overfishing occurs when more fish are taken from a population than are replaced through reproduction. Growth overfishing happens when fish are caught before they’re adequate size. In general, smaller fish are less able to reproduce.

Florida’s gag grouper suffers from both types, Dodrill said.

Research sponsors include UF/IFAS, the Fish and Wildlife Conservation Commission, the National Marine Fisheries Service and Florida Sea Grant. The first phase of the project began in 1990.

In that phase, called the Suwannee Regional Reef System, Lindberg’s team placed 1,350 one-ton concrete cubes on the ocean floor, stretched over a 26-mile strip about 20 miles off the Levy and Dixie county coasts. The cubes contain holes where the fish can hide.

The reefs—assembled in four- to 16-cube formations —were then studied, the fish counted, their condition monitored and their every habit scrutinized.

“The rest of the team has grown gills,” Lindberg jokes.

The gag grouper life cycle goes like this: A harem of a few males and many females spawn 100 miles offshore, the eggs hatch and the current carries the tiny fish to seagrass beds close to shore, where they spend their first summer. Over the next few years they leave their seagrass nursery, swim to deeper water and the cycle starts over—if they aren’t eaten by bigger fish along the way.

Lindberg and his team think they may help the gag grouper population with the new artificial reef system, called the Steinhatchee Fisheries Management Area. That system will include 1,600 cubes placed inside a 100-square-mile triangle.

The new reefs—just north of the first system—will shelter the fish from predators as they make what otherwise would be a precarious journey across the mostly flat ocean floor. Lindberg hypothesizes the trek causes a “bottleneck” in the gag grouper’s ability to reproduce.

Despite the reef project’s cost and time, Dodrill said his agency had no qualms.

“This is a pretty carefully thought-out design,” Dodrill said. “Something like this takes expertise and time and money—three tough things to bring together in one place.”

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