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US scientists warn of aggressive lionfish spread in the Caribbean

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NORTH CAROLINA, United States--United States scientists say the Caribbean's native predators are unable to stop the increasing growth of the aggressive lionfish. Researchers at the University of North Carolina (UNC) at Chapel Hill say while "ocean predator" conjures up images of sharks and barracudas, the voracious red lionfish is "out-eating them all in the Caribbean".

In addition, the researchers say "mother nature appears unable to control its impact on local reef fish. "That leaves human intervention as the most promising solution to the problem of this highly invasive species," said John Bruno, professor of biology in UNC's College of Arts and Sciences and lead investigator of the study.

"Lionfish are here to stay, and it appears that the only way to control them is by fishing them," he said, adding that the research has important implications not just for Caribbean reefs but for the North Carolina coast, where growing numbers of lionfish now threaten local fish populations.

According to the journal PLOS ONE, "native predators do not influence invasion success of Pacific lionfish on Caribbean reefs". Researchers say the Lionfish, native to the Indo-Pacific region, have long been popular aquarium occupants, with their striking stripes and soft, waving fins.

Bruno said they also have venomous spines - making them unpleasant fare for predators, including humans- though once the spines are carefully removed, lionfish are generally considered safe to eat.

Researchers say the lionfish have become big marine news as the latest invasive species to threaten existing wildlife populations.

Bruno likened their extraordinary success to that of ball pythons, now eating their way through Florida Everglades fauna, with few predators other than alligators and humans. Serena Hackerott, lead author and master's student in marine sciences, also in UNCs College of Arts and Sciences, said that when she began diving 10 years ago, lionfish were "a rare and mysterious species seen deep within coral crevices in the Pacific Ocean.

"They can now been seen across the Caribbean, hovering above the reefs throughout the day and gathering in groups of up to 10 or more on a single coral head," she said.

Researchers say they looked at whether native reef predators, such as sharks and groupers, could help control the population growth of red lionfish in the Caribbean, either by eating them or "out-competing them for prey".

They say they also wanted to evaluate scientifically whether, as some speculate, that overfishing of reef predators had allowed the lionfish population to grow unchecked. The researchers surveyed 71 reefs, in three different regions of the Caribbean, over three years, and that their results indicate there is no relationship between the density of lionfish and that of native predators, suggesting that "interactions with native predators do not influence" the number of lionfish in those areas.

Researchers say they did find that lionfish populations were lower in protected reefs, attributing that to targeted removal by reef managers, rather than consumption by large fishes in the protected areas.

Hackerott noted that, during the 2013 reef surveys, there appeared to be fewer lionfish on popular dive sites in Belize, where divers and reef managers remove lionfish daily.