Lemon sharks are being considered for protection. (Walt Stearns, Florida Fish and Wildlife Conservation Commission / November 19, 2009)
Undersea predators called vital to health of reefs
By David Fleshler, Sun Sentinel
They are the lords of the reefs, powerful 10-foot sharks that prowl shallow coastal waters, snatching stingrays, crabs and mullet.
But while lemon sharks can hold their own in the undersea jungle, they face a tougher time against the predators equipped with powerboats, baited hooks and satellite tracking devices.
The Florida Fish and Wildlife Conservation Commission this month is considering a ban on the catch of lemon sharks, hoping to protect a species that plays an important role in maintaining the health of coral reefs.
The proposal for the ban came from a group of scientists and environmentalists clustered around University of Miami professor Samuel Gruber, the world's foremost lemon shark expert. They fear that restrictions on catching other shark species over the past couple of years are leading fishermen to turn their attention to lemon sharks. Since 2004, the Florida lemon shark catch has risen more than 400 percent.
Because these sharks take years to mature and bear few young, they have difficulty recovering from heavy fishing pressure. In the 1980s in the Florida Keys, for example, where Gruber was tagging sharks, the entire population had virtually disappeared by 1986.
"It was targeted by commercial fishermen," he said. "They set huge gill nets and everything they caught went to the fish house for 10 cents a pound."
Adding to the lemon shark's vulnerability is the species' bizarre habit of assembling in large, stationary groups on the ocean floor. A couple of miles off Jupiter, for example, lies the biggest known aggregation of lemon sharks, with groups of up to 100 visible during the winter.
"They're lying on the sand, nose into the current, basically shoulder to shoulder like cars in a parking lot," said Walt Stearns, a professional undersea photographer from Palm Beach Gardens, who brought the assemblage of sharks to the attention of scientists.
Gruber describes this as the largest known congregation of lemon sharks on the East Coast of the United States, and he said it highlights the danger to the sharks from people.
"They could target and catch them and wipe them out in a matter of weeks," Gruber said.
Fort Pierce shark fisherman Joe Klosterman takes his 37-foot boat Gale Mist II up to 25 miles out to sea, where he deploys a longline baited with mullet, bluefish and bits of shark. He says he hasn't noticed a decline in lemon sharks and that a catch ban won't do the sharks much good.
Although he would be required to throw back any banned sharks he catches, he said that doing so will do little for the shark since at that point it would probably be dead.
"Some sharks die real quick on the lines," he said. And throwing one back would cost him the $300 or so he could have earned for the shark's fins alone, which are exported to East Asia for shark fin soup, a delicacy.
"Most fisherman are all for conservation," he said. "You want to see a sustainable fishery. But I don't see where this is going to save more sharks."
Lemon sharks, named for their yellow-brown color, live in coastal waters from the mid-Atlantic states to southern Brazil. They rank 13th in attacks on people, far below the "big three" for shark attacks: the great white, tiger and bull sharks, according to the International Shark Attack File at the Florida Museum of Natural History. There have been no known fatal attacks by lemon sharks.
The sharks play an important role in maintaining the health of shallow ecosystems, such as coral reefs, by preventing lesser predators from multiplying out of control, Gruber said. They hold down the population of stingrays, for example. Without this service, the stingrays would devastate the lobsters, with further consequences down the food chain.
"The lemon shark is one of the largest predators on the reef," Gruber said. "If you were to take away the predator pressure, you will cause an ecological disruption in the balance of species."
The wildlife commission will decide whether to approve a draft ban on lemon shark catches at its Dec. 10 meeting in Clewiston.
The commission's ban would apply only to state waters, which extend three miles off the east coast and nine miles off the west coast. But the federal government, which regulates fishing up to 200 miles off the coast — except where that zone would run into the Bahamas — may follow Florida's lead if the state requests it. Karyl Brewster-Geisz, fishery management specialist for the National Marine Fisheries Service, said states normally request comparable regulations in federal waters for consistency.
Staci-lee Sherwood, a Lighthouse Point animal rights activist who filed comments with the commission in support of the ban, said lemon sharks have far greater economic value if they remain in place to be seen by dive boats full of tourists, rather than killed for a few hundred dollars worth of fins and meat. But beyond that, she said, they have value beyond any use by human beings.
"I'm against any kind of cruelty to animals," she said. "I wouldn't justify killing any animal just for its fins or ivory or fur."
David Fleshler can be reached at dfleshler@SunSentinel.com 954-356-4535.