lionfish, an invasive species

The lionfish, with its highly venomous spines, is sighted several times during dive operations. Although it is a dramatic sight, it was not a joyous one. The lionfish is an invasive species, native to western Pacific waters.

We're Being Invaded

August 02, 2002

Pam Jutte, Marine Scientist
SC Department of Natural Resources

Josh Loefer, Biologist
SC Department of Natural Resources

Scott Meister, Marine Biologist
SC Department of Natural Resources

camera icon Watch a video sighting of a Lionfish, an invasive species. (mp4, 3 MB)

Many of us are familiar with invasive species— everything from kudzu creeping and crawling across the deep south, cane toads taking over Australia, zebra mussels overrunning the Great Lakes, and exotic clams infesting San Francisco Bay. In recent headlines, there has been intense debate over the appearance of snakehead fish in Maryland lakes. This imported aquarium fish from Asia, probably introduced by an unsuspecting aquarist, has the capacity to walk on land and survive out of water for several days. Because of its potential impact on native species, some wildlife biologists are recommending that everything in the infested lakes be killed to avoid the spread of this species.

Another invasive species that has recently made the news is the lionfish, Pterois volitans. This unmistakable marine fish with highly venomous spines is native to western Pacific waters. There are two theories about how it was first introduced into Florida waters. Some believe damage to the Miami Aquarium caused by Hurricane Andrew in 1992 allowed it to escape. Others surmise that, just like the snakehead fish in Maryland, an aquarist released it. Over the last few years, adult lionfish have now been reported in coastal waters from Florida through North Carolina. Juveniles have been spotted as far north as New York. During Leg 1 of Islands in the Stream 2002, we discovered lionfish on two submersible dives off of South Carolina at depths of up to 180 ft. We believe this is the deepest sighting of lionfish in this area.

Run-ins with an Invader

On the afternoon of August 1, 2002, Pilot Dan Boggess flew the JSLII along Scamp Ridge off the coast of South Carolina. Aboard were South Carolina Department of Natural Resources (SCDNR) scientists Scott Meister and Dan Russ.

Scott recalled his unforgettable dive:
We began our dive in the JSL II at about 4:30 pm. We'd been slowly hovering along the reef for a few hours when we came across a high rock ledge teaming with life. Schools of tomtate intermixed with vermilion snapper flashed above the feature, while small damselfish and wrasses darted in and out of the small holes in the reef. Soft coral and sponges adorned much of the face of the wall, and a spiny lobster could be seen clinging upside down to a small overhang. Having been down on the reef about two hours already, my eye had become accustomed to the standard shapes and sizes of the species we'd seen throughout the dive. We were on the prowl for a sponge sample to bring to the surface when I spotted what I first believed to be an unusual coral outcrop of some type. Long, slender spikes peeked out from behind a small rock mound and my interest was immediately piqued.

As we came closer and saw the spines fully, an odd-looking fish rose above the mound and turned to see what all the commotion was about. My heart jumped into my throat as I realized it was a lionfish! Everything about this fish seemed out of place when compared to the species we had observed so far. Long, sharp spines ran up its back, nearly twice the height of its body. Its pectoral fins resembled wings, again lined with sharp, slender spines. Its color contrasted strongly with the surrounding reef, with a zebra-like pattern of brown and white vertical bars along its body and dark circles imprinted on a translucent tail. This invader didn't dive for cover as many other fish its size did, but instead seemed to assume a defensive posture and moved towards our 26,000-pound submarine! Maybe these hollow spines present a formidable defense against any potential predators.

This dive was an amazing opportunity. Unfortunately, we sighted the lionfish late in the dive, and the sub was low on battery power. This gave us only a few minutes to try to capture this noteworthy specimen. During a short and heated pursuit, we spotted a second lionfish. We made several attempts to capture both fish without success. Before we knew it, time was up, and we had to surface and leave the lionfish behind. Although we did not return to the surface with a physical specimen, we did return with proof of our unlikely encounter on videotape.

Encountered Again

On the following day, the science team made another submersible dive on a similar reef approximately six miles away from the initial lionfish sightings. This time, Pilot Craig Caddigan maneuvered the sub through the reef while SCDNR Scientist Josh Loefer and Jeremy Potter of NOAA Ocean Exploration took responsibility for the science.

Josh, seated in the front of the JSL II with the pilot, was in the middle of "Lionfish: The Sequel."

Our hopes were high that we would have another opportunity to capture a live specimen. We didn't have to wait long. Only thirty minutes into the dive, we sighted another lionfish. We had plenty of battery power this time, so the lionfish was as good as ours. Or was it? The area in which we encountered the lionfish was extremely rocky, and provided a large number of hiding places for our quarry. Nevertheless, the chase was on. At times, it appeared as though the lionfish was toying with us. It would allow the suction nozzle to come within inches of its body, so close that we could see its fins ripple in the current created by the suction pump, but would dart away at the last moment and find cover. We would then relocate the lionfish, flush it from its hiding place, and try to capture it again. After a 30-minute chase with multiple capture attempts, the lionfish finally found a large rock overhang about 4 feet deep. It darted inside this well protected area, putting itself well out of reach of the submersible. Lionfish: 2, scientists: 0.

With our quarry out of reach, we reluctantly moved on and continued our scheduled dive activities. By the end of the dive we had spotted two more lionfish, which we did not have time to pursue. This brought the lionfish total to five sightings. Though it was exciting to see this many lionfish in a short amount of time, these sightings suggest that the lionfish has established a foothold in this non-native environment, and may be actively reproducing in the waters off South Carolina.

What to do?

Whatever the source of invasive species—ballast water, release from aquaria, or planned introductions by managers gone awry—non-native organisms are of great concern to biologists because of the alarming effects they can have on the ecology of terrestrial, aquatic, and marine environments. Many of these species have no natural predators in the invaded habitat, and are thus able to proliferate unchecked. In the process, they take over habitat and consume food sources previously used by native species. The end result can be the loss of native species, decreased ecological complexity, and dominance by the invaders.

Release from personal aquaria continues to be one of the leading causes of the introduction of marine invasive species. Sometimes aquarium owners get tired of caring for their exotic pets, either because the novelty has worn off or because the fish has outgrown its aquarium. Eventually, owners release their former pets into the ocean to swim free. Unfortunately, these well-intentioned releases often have severe and lasting consequences.


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