Invasive lionfish reaches Brazilian waters

A lionfish -- normally seen in the Gulf of Mexico and the Caribbean -- has made a remarkable journey to reach Brazilian waters.

The piscine pioneer was spotted by a group of recreational divers in a reef off Cabo Frio, a municipality of Rio de Janeiro in southeastern Brazil. The divers returned to the site the next day with hand spears and captured the fish for the scientists to study.

When the researchers analysed the fish's DNA, they found that it matched the genetic signature of the Caribbean lionfish population and not that of specimens from their native Indo-Pacific region.

"This suggests that the fish may have reached Brazil through natural larval dispersal from the Caribbean," the authors wrote.

But according to Mark Hixon, marine ecologist at the University of Hawaii in Manoa, ocean currents typically flow in the wrong direction for larval dispersal from the Caribbean to the southeastern Brazilian coast.

It is just as likely that the lionfish was brought to Brazil by humans.

"Lionfish are easy to capture and make beautiful pets. It is easy to imagine boaters carrying lionfish as short term pets in bait tanks or other containers on their vessels," Hixon noted.

Researchers reported the first confirmed lionfish in Brazilian waters in PLoS ONE. However the lionfish got to Brazil, its arrival is not surprising.

James Morris, marine ecologist with the US National Oceanic and Atmospheric Administration in Beaufort, North Carolina, has been predicting since 2009 that the fish would eventually spread as far south as northern Argentina.

But Morris says that it is not clear whether the first reported lionfish in Brazil is a "lone ranger" that might not be joined by other fish for years or whether it heralds an imminent rapid increase in lionfish numbers.

"It's going to have to be one of those wait-and-see sort of situations," he says.

Lionfish are voracious predators, indiscriminately eating anything small enough to fit in their mouths -- such as native fish and crustaceans -- in large quantities.

Scientists are concerned that Brazilian waters are especially vulnerable to lionfish, said the report in the scientific journal Nature.