Lionfish hunters are being urged to stop feeding speared lionfish to predators, including moray eels, amid concerns that they are showing more aggressive behaviour toward divers.
The warning comes as new research in the US shows marine creatures have not learned to prey on lionfish, which have no natural predators in the Atlantic and are a threat to other species because of their voracious appetite.
The average lionfish eats 60,000 reef fish before it is 2 years old, according to researchers. It had been hoped that eels, snapper and reef sharks could be “taught” to target the fish, curbing its unchecked population explosion across the Caribbean and beyond.
But environmental watchdogs say this doesn’t work and is only making predators associate divers with food.
John Ferguson, one of the founding members of the Cayman United Lionfish League, was bitten on the hand by a green moray eel as he hunted for lionfish during a dusk dive last week.
Mr. Ferguson is concerned that the practice of directly feeding eels is changing their behaviour, making this usually shy creature more of a nuisance to divers. He and other regular lionfish hunters have warned that they are often followed by eels on dives at all times of day.
”We are seeing more aggressive behaviour from snappers, eels and groupers. This can be attributed to people culling fish and either feeding them directly or just leaving them on the reef for something to eat. Now we not only have spotters for lionfish, we have the need for predator spotters to warn of approaching danger.
“I ask that we stop this feeding underwater immediately. The message has to be, if you spear a lionfish, put it in a containment device and take it out of the water.”
It is illegal to feed fish or encourage wildlife interaction in Cayman’s territorial waters outside of Stingray City and sandbar, according to the Department of Environment.
Jason Washington, another member of CULL and the operator of Ambassador Divers, said the practice was done with the best of intentions by divers who wanted to encourage potential predators to associate lionfish with food. But he said research suggested they were actually linking divers with food and becoming more aggressive.
The solution, he said, was for all lionfish hunters to carry a containment device, rather than leaving dead fish on the reef or on the end of their spears for other fish to eat.
“It is not that diving here is dangerous. We have a small issue that can be easily fixed with a little education. Feeding lionfish to predators has been shown to be ineffective. It is not doing anything, except creating trouble for ourselves,” Mr. Washington said.
He added that there were potential consequences for any type of human activity that changed the behaviour of fish.
Bradley Johnson, a research officer at the Cayman Islands Department of Environment, said feeding lionfish to predators does more harm than good.
“We don’t want people to do it,” he said. “It is against several marine conservation laws. You are not only endangering yourself, you are endangering everyone else who uses that site by teaching the predators to associate divers with food.”
Mr. Johnson said divers had reported being harassed by moray eels and there had been instances of other divers being bitten, both by eels and barracuda, across the Caribbean.
A study published last week by the University of North Carolina showed that predators had no influence on lionfish abundance.
“Lionfish are here to stay, and it appears that the only way to control them is by fishing them,” said Professor John Bruno of the research team.
The research, detailed online 11 July in the journal PLOS ONE, focused on the effect of natural predators, such as sharks and groupers, on the population of two species of red lionfish on 71 reefs of the Caribbean over three years.
The manual “Invasive Lionfish: A Guide to Control and Management”, a reference book produced for professionals involved in lionfish control, also warns feeding lionfish to predators has not proven to have any effect and is actually dangerous and counter-productive.
It states: “There is no conclusive evidence that native predators are learning to prey upon lionfish. Unexpected effects of fish feeding activities include aggressive changes in predator behaviour during interactions with divers.”
Mr. Ferguson urged all lionfish cullers to take their catch out of the water and take advantage of the nine restaurants currently buying the fish at around $5 a pound.
“We have got to eat them to beat them. It’s the only way,” he added.