Population explosion of Pacific species is threatening wildlife in western Atlantic and Caribbean waters
They are stunningly beautiful and a big draw for aquariums, but that's where the attraction ends. The Pacific lionfish has proved so unappealing to sharks and other ocean predators that a population explosion is threatening the delicate ecosystems of a new habitat: the western Atlantic and Caribbean.
Lionfish are relatively minor players in their native waters in the western Pacific, but in their new habitat they have been spectacularly successful and are already having a significant impact on the Bahamas and Cuba.
The problem is that they are as voracious as they are attractive, gobbling up vast amounts of young fish, particularly around coral reefs. Their victims include species that keep algae from overwhelming reefs already suffering from human-engendered destruction. They are also diminishing the stocks of food sustaining dwindling populations of commercially exploited fish.
"This is the beginning of the invasion for us, but we have seen how quickly infestations have developed elsewhere," says Ricardo Gomez, director of a national marine park in the island of Cozumel, where Mexico's lionfish are most concentrated. "We have to act quickly."
Nobody knows how lionfish got into the Atlantic, although the most commonly held theory is that they were released from aquariums in Florida in the 1990s.
Periodic sightings increased until it became clear that there was a full-scale population explosion going on in around 2006, initially around the Bahamas.
Lionfish are now found in much of the Caribbean, the US eastern seaboard and down into South America. The fish do not migrate, but their eggs can survive for several days as they float in marine currents.
Since the first sightings near Mexico, off Cozumel in January 2009, lionfish are now regularly spotted almost all the way down the Yucatán peninsula, following one of the great coral reefs of the world. A few weeks ago there was also a sighting in the Gulf of Mexico, to the north.
Scientists do not know why they are doing so well in the Atlantic, but studies suggest their prey take no evasive action when they see them coming.
Bigger predators, including sharks, are also notably disinclined to eat them, apparently deterred by their feathery, venomous spines to the point of spitting them out. Even parasites do not seem to take to lionfish.
"It is as if nothing can stop them," said Mark Hixon, a zoologist from Oregon State University who is currently trying to determine what helps keep them in check in the Pacific. "The best we can hope for is that the native species [in the Atlantic] will eventually react to the lionfish."
In the meantime, efforts to control the invasion are focused on brigades of divers physically removing them from the water. In some places, such as Cozumel, the battle against the lionfish includes tournaments where the diver who brings out the most lionfish gets a prize, and everybody shares a barbecue at the end.
At least one US company is already trying to market lionfish to restaurants as a gourmet dish.
"This is an international problem and it needs a co-ordinated international solution," said Gomez. "I don't think we can ever hope to eradicate them, but if we work together we can hope to control them."
