July 12, 2013
Lionfish Invasion May Call For Human Intervention
Brett Smith for redOrbit.com - Your Universe Online
With almost daily reports detailing how human activities are decimating other species, researchers from the University of North Carolina are making the unique call for human intervention in controlling the Atlantic Ocean's lionfish population."Lionfish are here to stay, and it appears that the only way to control them is by fishing them," said John Bruno, a UNC biologist and lead investigator in a new study detailing the lack of lionfish predation that was recently published in the journal PLOS ONE.
Along with a team of fellow American and Canadian marine biologists, the UNC researchers investigated the proliferation of lionfish in three Caribbean regions. Using a deep-diving submersible, the team was shocked to find major populations of these predatory fish as deep as 300 feet below the surface.
"We expected some populations ofâ€¯lionfish at that depth, but their numbers and size were a surprise," said co-author Stephanie Green, a research fellow at Oregon State University. "This was kind of an 'Ah hah!' moment."
"It was immediately clear that this is a new frontier in the lionfish crisis, and that something is going to have to be done about it," Green said. "Seeing it up-close really brought home the nature of the problem."
Native to the Pacific Ocean, lionfish were accidentally introduced to the Atlantic Ocean in the early 1990s. Without any limiting factors in their new habitat, the ravenous predators swarmed across the Caribbean, reducing various native fish populations by up to 80 percent, according to previous OSU research.
"When I began diving 10 years ago, lionfish were a rare and mysterious species seen deep within coral crevices in the Pacific Ocean," said co-author Serena Hackerott, a master's student in marine sciences at UNC. "They can now been seen across the Caribbean, hovering above the reefs throughout the day and gathering in groups of up to ten or more on a single coral head."
A popular aquarium fish, lionfish have venomous spines in addition to their striking colors and majestic fins. The spines generally make lionfish unappealing for most predators. However, they are eaten by humans - once the spines have been removed.
The researchers said they looked to see if sharks or groupers could help control the lionfish population by out-competing them for prey or eating them directly. They also wanted to determine if overfishing of reef predators had opened the door for an unchecked lionfish invasion.
After surveying 71 disparate reefs over three years, the team said they saw no relationship between the density of lionfish and the concentrations of native predators, suggesting that "interactions with native predators do not influence" the lionfish population. They noted, however, that targeted removal by reef managers had reduced lionfish populations in some protected reefs.
The marine biologists suggested the large-scale introduction of reef predators to achieve a better balance and biodiversity for the fragile ecosystems. However, they made pessimistic predictions about the success of such a plan.
"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.