Human efforts called best way to control lionfish

Controlling lionfish populations in the Caribbean is a job for humans not ocean predators, according to a new study of the invasive fish species.

Lionfish, known for their voracious appetite and the ability to herd and eat smaller sea creatures, are dwellers in Costa Rica’s Caribbean reefs.

An earlier study said that approximately 27 percent of mature lionfish will have to be removed monthly for one year to reduce its population growth rate to zero. The fish has no natural enemies in the Caribbean or Atlantic. The only way to do this is with human intervention, according to the new study by researchers at the University of North Carolina at Chapel Hill.

“Lionfish are here to stay, and it appears that the only way to control them is by fishing them,” said John Bruno, professor of biology the university and lead investigator of the study. The research has important implications for Caribbean reefs. He was quoted by the university.

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

In fact, the National Oceanic and Atmospheric Administration and North Carolina State University once announced an eat lionfish campaign. Lionfish are not easy to get with a hook and line, but divers find that they can be approached easily and caught with spear or net.

North Carolina State’s Seafood Laboratory reports that the fish has a white, somewhat firm flesh and a mild flavor, slightly similar to snapper. Cooks are advised to watch out for the poisonous spines that can still deliver a healthy but non-fatal dose even after the fish is harvested, said the university in its 2010 study. The spines can be cut off with shears.

Bruno at the University of North Carolina likened the extraordinary success of the liionfish to that of ball pythons, now eating their way through Florida Everglades fauna with few predators other than alligators and humans.

“When I began diving 10 years ago, lionfish were a rare and mysterious species seen deep within coral crevices in the Pacific Ocean,” said Serena Hackerott, lead author of an academic article and master’s student in marine sciences at the Chapel Hill university. “They can now be 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.”

The University of North Carolina international research team 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, according to a university summary of the research.

They also wanted to evaluate scientifically whether, as some speculate, that overfishing of reef predators had allowed the lionfish population to grow unchecked, the summary said. The university gave this description of the study:

The team surveyed 71 reefs, in three different regions of the Caribbean, over three years. 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, the study said.

The researchers 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.

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

The researchers support restoration of large-reef predators as a way to achieve better balance and biodiversity, but they are not optimistic that this would affect the burgeoning lionfish population, the summary said.

“Active and direct management, perhaps in the form of sustained culling, appears to be essential to curbing local lionfish abundance and efforts to promote such activities should be encouraged,” the study concluded.

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