Research by US scientists in the Cayman Islands suggests native predators can be trained to gobble up invasive lionfish that colonise regional reefs and voraciously prey on juvenile marine creatures.
The invasive species with a flowing mane of venomous spines has no natural predators in the Atlantic and Caribbean Sea. Native sharks and groupers typically avoid healthy lionfish, a native to the Indian and Pacific oceans that was likely introduced through the pet trade.
But when a University of Florida team tethered lionfish to lead weights on reefs off Little Cayman, underwater video cameras showed nurse sharks and Nassau groupers gulping them down.
Thomas Frazer is one of the researchers and the director of the University of Florida's School of Natural Resources and Environment. He said the study suggested that sharks and groupers "have the capacity to learn to pursue, capture and consume" lionfish without human intervention.
"Findings from this study simply suggest that conditioning is likely to facilitate the learning process. On a local scale, predation on lionfish by sharks and groupers is likely to enhance culling efforts," Frazer said.
Some researchers and lionfish wranglers not involved in the study expressed doubt about the findings, arguing that tethered fish did not behave naturally and likely triggered an unusual feeding response in predators.
"I am highly sceptical that a native predator eating a tethered lionfish means that those predators will eat untethered lionfish," said Mark Hixon, a University of Hawaii professor of marine ecology and conservation biology who has studied the lionfish invasion.
Lad Akins, of the Reef Environmental Education Foundation, a Florida-based organisation of divers and marine enthusiasts, said he believed feeding lionfish to native predators in the Cayman Islands or anywhere else was dangerous.
"A number of people have been bitten, sometimes badly, by conditioned predators ," Akins said.
In a published report on their research in the Journal of Experimental Marine Biology, Frazer and his fellow researchers stressed that any attempt to train native predators "must be done in a way that minimises threats to humans who share the environment with the predators being trained and invasive lionfish".