Goliath grouper have become the scapegoat for a depleting spiny lobster harvest, and sport fishermen also blame them for gobbling up snappers before they can reel their catch in.

A recent study has vindicated the much maligned fish. Independent scientist Sarah Frias' study, released this month, found that goliath groupers are not the cause for declining lobster and snapper stocks in Florida. Overfishing is the main cause, she found.

The goliath grouper fishery has been closed for 16 years, about the average generation time of the fish and about twice the time it takes for a newborn to reach sexual maturity.

Commercial and recreational fishermen have proposed culling -- or thinning -- the stock with the expectation of increasing lobster and snapper yields. It's a recurring argument the past two years from those who say the species has made a full recovery, despite evidence that fisheries remove far more than ocean predators.

Frias analyzed the food web of the goliath grouper and other fish that feed on lobsters and snappers.

"Based on the evidence presented here, the recovering trends of the goliath grouper are not directly responsible for declining commercial landings of spiny lobster and gray snapper," she states in her study. "The most likely cause is commercial and recreational overfishing."

Sea turtles and dolphins also eat lobster, but "You don't see anyone asking to kill them," Frias said.

"A potential reopening of the goliath grouper fishery in Florida for culling purposes raises ecological, socioeconomic and ethical concerns," she said.

Lower Keys commercial fisherman, diver and conservationist Don DeMaria agreed that goliath groupers have been unfairly targeted as the cause of the spiny lobster decline.

"How does one explain that years ago, before our fisheries were heavily exploited -- there were many more goliath grouper in the Keys than there are today -- and there were also many more lobster, and they were bigger?" DeMaria asked. "It is estimated that somewhere between 85 to 90 percent of the legal-size lobster are harvested each year from our area by humans, yet the goliath grouper takes the blame for any reduction in landings. The numbers don't quite add up here."

Divers play a large role in the take of lobsters each year, DeMaria said. Fishermen are not willing to admit they are contributing to overfishing, he said.

"The sporties blame the commercial fishermen, and the commercial fishermen blame the sporties," DeMaria said. "Now both sides blame the goliath grouper for every and all shortages. It is no wonder our fisheries are in such bad shape. No one is willing to take responsibility for their actions."

He added, "If it were left up to the sporties and commercial interests to regulate our fisheries, the commercial fishermen would fish it down to the last fish and the sporties would hold a tournament to see who could catch that last fish."

Fishermen are already harvesting the fish illegally year-round, DeMaria said.

Last year, a photo of a living goliath grouper with a spear tip in its head was given to Florida Fish and Wildlife Conservation Commission (FWC) and Florida Keys National Marine Sanctuary, with a request that officers look out for divers spearing goliath groupers at Bahia Honda Bridge.

A January 2010 cold snap may have affected future populations, according to Chris Koenig, a Florida State University marine biology professor who has conducted research on goliath grouper. The cold may have killed up to 95 percent of the juvenile population in the Everglades and other mangrove areas off Florida, making this is "poorest possible time to open (the fishery) up," Koenig said.

The juveniles spend their first five years in the shallow mangrove habitats.

Rock star, lionfish tamer

Instead of killing them, fishery managers should be showcasing them, Frias said. The goliath grouper is the largest of the western Atlantic Ocean grouper. They can reach 8 feet long and 880 pounds.

The goliath grouper's enormous size, formation of spawning aggregations and curiosity of divers makes it a major attraction for scuba divers, especially on wrecks. The fish are known to congregate in large numbers on artificial reefs. Dive boat operators regularly visit wrecks and reefs they frequent.

"Diving ecotourism as an alternative to overfishing provides more value to local economies," Frias said. "You can only kill them once. You let them live and they can continue to be an economic benefit. People can continue to see them over and over again ... .

"The charismatic long-lived goliath grouper could benefit from dive ecotourism as a sustainable alternative to overfishing and dive ecotourism could become a key strategy to ensure the conservation of the species."

While they bring in divers, the goliath grouper also can help get rid of lionfish, an unwelcome species that also hangs out on wrecks.

The venom-spined, invasive, and voracious lionfish has found its way into Florida Keys waters, as well as other areas of the eastern seaboard, the Gulf of Mexico and the Caribbean.

The goliath grouper exploits a unique niche by feeding on venomous fish, Frias said. Such fish include cowfish, trunkfish, porcupinefish and pufferfish.

"The goliath grouper's adaptation to feeding on poisonous and venom-spined fish could potentially serve as a natural biocontrol for invasive lionfish," Frias said.

She did concede, however, that there were no documented cases of goliath grouper feeding on lionfish.

To open or not to open?

Both state and federal fishery managers have said they lack enough information about the fish to keep closed or reopen the fishery, which was limited to catch-and-release in 1990.

Some have urged fishery managers to allow a certain number of the groupers to be harvested for research purposes, facilitating a more accurate stock assessment.

The FWC agreed in 2011 to empanel the Ad Hoc Goliath Grouper Steering Committee to study goliath grouper; it has met twice in the past year.

The committee comprises representatives from the Gulf of Mexico and South Atlantic Fishery Management councils, National Oceanic and Atmospheric Administration and FWC, said Amanda Nalley, FWC spokeswoman. The committee is to find a way to assess the stock and collect other information -- but current methods to get that data mean catching and dissecting goliath grouper.

The committee decided to develop a "stakeholder survey" to determine expectations of those concerned about goliath grouper management, Nalley said.

The survey would poll parties in Florida as well as Alabama, Mississippi, Louisiana, Texas, Georgia, South Carolina and North Carolina. It's projected to be completed in January 2013.

Subsequently, a science workshop will be held the month after that so goliath grouper experts can offer suggestions for research, analyses, modeling, and other data. A workshop would follow in March 2013, Nalley said.

A list of desired goals will be prepared based on input and presented to each council that April.

FWC staff will brief the commission at the agency's April 2013 meeting, and finally, the councils will give their staff direction on the next steps for goliath grouper in June.

An update to the FWC board will likely be presented sometime in 2013, Nalley said.

In 2006, researchers with the Florida Fish and Wildlife Research Institute proposed a stock assessment that would have allowed the harvest of 800 goliath grouper over two years. The assessment was scrapped after several scientists and conservationists opposed it, Koenig said.

There are ways to conduct stock assessments that would give age data without killing fish, Koenig said.

He has conducted studies that determine age by the number of rings on their dorsal fins, similar to how a tree's age is determined.

tohara@keysnews.com