The lionfish, which originally came from the Indo-West Pacific Ocean, has established self-sustaining populations along the U.S. eastern seaboard, the Gulf of Mexico, and the Caribbean at an unprecedented pace, according to the U.S. Geological Survey.

"Nothing like this has been seen before in these waters," said Dr. Pam Schofield, a biologist with the USGS Southeast Ecological Science Center, in a press release last week. "We've observed sightings of numerous non-native species, but the extent and speed with which lionfish have spread has been unprecedented; lionfishes pretty much blanketed the Caribbean in three short years."

More than 30 species of non-native marine fishes have been sighted off the coast of Florida alone, but until now none of these have demonstrated the ability to survive, reproduce, and spread successfully. While it is not clear how the new invasive species will affect reefs in this part of the world, lionfish are predatory and thus may adversely affect native species in the newly invaded ecosystems. They have already been observed preying on and competing with a wide range of native species.

Invasive lionfishes were first reported off Florida's Atlantic coast in the mid-1980s, but did not become numerous in the region until 2000. Since then, the lionfish population has rapidly spread north through the Atlantic Ocean and south throughout most of the Caribbean. The spreading population is now working its way around the Gulf of Mexico.

Map showing northward movements of lionfish into the Gulf of Mexico. Timelines indicate when lionfishes were first sighted in a particular region. The star indicates an anomalous lionfish record from 2006 thought to be a recent aquarium dump.

Schofield spent years compiling and verifying sightings of lionfishes, reaching out to local experts such as biologists, museum curators, natural resource managers, dive-masters and citizens groups to collect detailed records of specimen collections and sightings throughout the region. The records were compiled in the USGS Nonindigenous Aquatic Species database and used to map the fishes' spread.

No one knows for sure exactly how the predecessors of the current population first made it into the Atlantic and Caribbean, but they have established themselves so successfully in their new habitat that many Caribbean countries such as Bermuda and the Cayman Islands have begun lionfish control programs in an effort to prevent them from wiping out indigineous fish populations.