August 15, 2008

Poisonous Lionfish Invades Caribbean

A red lionfish is quickly multiplying in the warm waters of the Caribbean, wreaking havoc on the ecologically delicate area.  The lionfish, an 18-inch maroon-striped marauder with venomous spikes, is stinging divers and swallowing native species from the coasts of Cuba to Little Cayman's unspoiled Bloody Bay Wall.

The area is one of the region's prime destinations for divers.   

The red lionfish, a white creature with maroon stripes, is a tropical native of the Indian and Pacific oceans, but most likely escaped from a Florida fish tank during the aftermath of Hurricane Andrew in 1992.

The adaptable predator uses its fins to suck down fish and crustaceans up to half its size in one violent swallow. One lionfish ate 20 small fish in less than 30 minutes, according to reports by research teams in the area.
"This may very well become the most devastating marine invasion in history," Mark Hixon, an Oregon State University marine ecology expert, told the Associated Press.

"There is probably no way to stop the invasion completely," said Hixon, who likened the lionfish to a plague of locusts.

It resembles something that may have survived a paper shredder, but with poisonous spikes along its spine to deter potential enemies.

The red lion's Caribbean invasion is similar to that of other aquarium escapees, including walking catfish and caulerpa, a fast-growing algae called "killer seaweed" for its ability to crowd out native plants. The catfish, now common in South Florida, threaten smaller fish in wetlands and fish farms.

In Africa, the Nile Perch caused more than 200 fish species to become extinct after it was introduced into Lake Victoria. The World Conservation Union called the Nile Perch one of the 100 worst alien species invasions.

"Those kinds of things happen repeatedly in fresh water," Hixon said.

"But we've not seen such a large predatory invasion in the ocean before."

The lionfish has thus far been concentrated in the Bahamas, and has been observed by marine biologists in nearly every habitat, including reefs, off beaches and piers. Alarmingly, the lionfish have been seen in mangrove thickets, which are vital habitats for baby fish.

Some spots between New Providence and the Berry Islands are reporting a tenfold increase in lionfish during the last year alone. The Northern Caribbean islands have gone so far as encouraging fishermen to capture the lionfish and have advised divers to report them for elimination.

Should the invasion reach Puerto Rico and the U.S. Virgin Islands it would be "devastating" to fisheries and recreational diving, said Eugenio Pineiro-Soler of the Caribbean Fishery Management Council.

"I think at the best they will have a huge impact on reef fish, and at the worst will result in the disappearance of most reef fish," Bruce Purdy, a dive operator who has assisted with expeditions tracking the invasion, told the Associated Press.

Purdy has been stung many times while rounding up lionfish, he said.  One time was particularly severe, he said. 

"It was so painful, it made me want to cut my own hand off."

Experts believe the lionfish were introduced into the Atlantic in 1992, during the aftermath of Hurricane Andrew, which had destroyed a private aquarium.  According to reports by the National Oceanic and Atmospheric Administration (NOAA), six of the fish spilled into Miami's Biscayne Bay.

Biologists think the fish may have released floating sacs of eggs that were carried north along the U.S. coast with the Gulf Stream, resulting in colonization of deep reefs off the coast of North Carolina and Bermuda.

Lionfish have even been seen as far north as Rhode Island during the summer months, according to NOAA.

Lionfish are not hostile or aggressive toward humans, and there are no estimates to date of tourists who have been stung. And although their sting is not fatal, marine officials say swimmers will be at increased risk as the venomous species invades the tropical waters along popular Caribbean beaches.

The slow-moving fish is easy to capture, but typically swims too deep for divers to catch with nets, a common way of neutralizing such invasive species.
Researchers are now scrambling to figure out what species might prey on the fish in their new Caribbean home, and are experimenting with predators such as moray eels, sharks and even humans "“ something that has been a hard sell so far, despite reports that lionfish fillets taste similar to halibut. And even ravenous sharks veer away when researchers try to feed them a lionfish.

"We have gotten (sharks) to successfully eat a lionfish, but it has been a lot of work. Most of our attempts with the moray eel have been unsuccessful," Andy Dehart of the National Aquarium in Washington, told the AP.

Though rarely found in the lionfish's natural Southeast-Asian habitat, grouper is one predator that will eat the lionfish. Long term, scientists are hoping that new ocean reserves can be established to protect grouper and other potential predators from overfishing.

Hixon said there are signs the lionfish have not yet moved into reefs of the protected Exuma Cays Land and Sea Park, a 176-square-mile reserve southeast of Nassau.  But unprotected areas in the vast archipelago are more susceptible.

Scientists face an uphill battle in containing the spread of the lionfish. As they continue to colonize more Caribbean territory, they feed on grazing fish that prevent seaweed from overwhelming reefs already battered by pollution and other environmental forces.

It's something that concerns Dehart.

"If we start losing these smaller reef fish as food to the lionfish...we could be in a whirlwind for bad things coming to the reef ecosystem," he said.

Image Courtesy Jens Petersen, Wikipedia


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