Jaws it's not, but new US resident is no pal

It hasn't exactly reached Spielbergian infamy, but a new invader – carnivorous and packing nasty venom in its spines – is prowling the waters off the East Coast, causing scientists to scratch their heads and divers and fishermen to think twice.

East Coast sightings of the lionfish – pterois volitans – have been reported by divers since the early 1990s. But confirmation came last month when a commercial fisherman off St. Augustine, Fla. hauled in a 6.75-inch lionfish and state scientists issued a warning to divers and anglers. Since then there have been numerous sightings, from south Florida up to North Carolina and Long Island.

How this species made the 10,000-mile swim to the Atlantic from its native waters of the western Pacific off southeast Asia and Australia is a riddle that leaves marine biologists scratching their heads – and the rest of the swimming public just wondering how to avoid the creature.

The lionfish thus joins the ranks of invasive species whose better-known and widely despised members include the European green crab, Asian eels, and zebra mussel. Although it's too early to measure just how many waves the lionfish will make on the Atlantic Coast, other unwelcome creatures already have a record of causing serious problems for local ecosystems.

"When a new species is introduced into an area, it can take over the niche, or job, of a native species, sometimes thriving to such a degree as to squeeze the native out of house and home," says Thane Maynard, of the Conservation Foundation in Cincinnati.

Lionfish are usually found in depths of at least 80 feet and in waters warmer than 78 degrees F. They can grow up to 17 inches long, and have maroon bodies with vertical white stripes. The most distinctive feature is a fan of prickly spines that secrete a poison that can cause severe pain, numbness, paralysis, and even death.

But back to the riddle: How did the lionfish get to the Atlantic? Maybe the lionfish migrated from the Indo-Pacific. No way, say scientists. The tropical fish couldn't survive the cold water between the two oceans.

Others believe the lionfish off the Atlantic Coast are aquarium pets turned loose.

"People buy these fish, and they either get too large for the aquarium, or they find out that the lionfish will eat the other fish," says Dan Roberts, a research scientist at the Florida Marine Research Institute who has been investigating lionfish spottings for the past two years. "Then they'll release the fish into the ocean. Maybe over 25 years of this going on, the lionfish has reproduced and become established."

Related to this theory is the ballast-water concept, in which larvae or juvenile fish are trapped in ships moving from the Indo-Pacific to the East Coast and are then released into local waters when the ballast water is pumped out.

Donald Hoss, director of the National Oceanic and Atmospheric Administration's Beaufort lab in North Carolina, says many species have been introduced to foreign ecosystems in this manner.

Wolfgang Sterrer, curator of the Bermuda Natural History Museum, has also been hot on the case of the lionfish.

"I've heard there are people in south Florida who actually breed lionfish in outdoor nurseries, and Hurricane Andrew could have sucked these fish up and dumped them offshore," says Mr. Sterrer, who is also a marine biologist.

In any event, scientists conclude that the lionfish was introduced to the Atlantic by man. But with no definite answer on just how that happened, Jon Shenker, a marine biology professor at Florida Tech in Melbourne, Fla., offers his own lighthearted – Spielbergian – theory: "They were picked up by alien spaceships and mysteriously transported to the East Coast as the beginning step of a alien-inspired worldwide lionfish epidemic."