Lionfish Surveys and Removal
Monitoring for lionfish at Gray's Reef National Marine Sanctuary is being conducted to better
understand the impacts this invasive species may be having on sanctuary resources.
Research and scientific diver, Dr. Michelle Johnston, removes a lionfish using a spear pole, gloves, and
plastic handling bag.
Although the threats of introduced species to habitats they colonize is often unknown beforehand, some
can have serious detrimental impacts, such as competition with native species for food and space, alteration of habitat, and
predation on native species. The National Marine Sanctuaries has been witness to the invasion of the lionfish, which is thought
to have been introduced to the east coast through aquarium "dumping," given that they are popular ornamental fish. Lionfish
(Pterois volitans/miles), formerly residents of the western Pacific, Red Sea, and eastern Indian Oceans only, were first
reported in the 1980s along south Florida and are now well established along the Southeast U.S., Caribbean, Bahamas, and Gulf
Venomous spines adorn the invasive lionfish.
Lionfish have distinctive maroon and white zebra stripes; fleshy tentacles above the eyes and mouth;
fan-like pectoral fins, and a plume of dorsal, pelvic, and anal spines that are all venomous and can cause extreme pain. They
live in all habitat types, from shallow mangroves and rocky outcrops, to coral reefs and artificial substrates as deep as 500
feet below the surface. Lionfish may live decades and reach sizes up to 20 inches. They reproduce year round, and since most
reef fishes only spawn once a year, lionfish may quickly outnumber native reef fish populations. Lionfish are also
indiscriminate ambush predators, and once they invade an area, they can be considered one of the top predators in many coral
reef environments in the Atlantic and Caribbean region. Their diet includes many smaller species of fish and invertebrates, as
well as the juveniles of the larger fish species, including commercially and recreationally important snapper and grouper. Not
only can this affect the balance of the local food chain by altering the structure of native reef fish communities by
out-competing native reef organisms and reducing forage fish biomass, but it can also impact fisheries by depleting commercially
and recreationally important species. For this reason, sanctuary resource managers and scientists are concerned about the
potential impact lionfish could have on the coral reef ecosystem, which supports the tourism and fishing industries.
Lionfish at Savannah's Snapper Banks.
(Photo: Greg McFall, GRNMS)
The venomous protective spines of lionfish, combined with their feeding habits, fast reproductive cycle,
and few natural predators in southeastern waters, all contribute to their successful invasive abilities. Lionfish can threaten
local ecosystems, and impacts from lionfish could include direct competition with the grouper/snapper complex for food and
predation on native reef fish and crustaceans. Also, lionfish pose a danger to divers and fishermen - stings from the venomous
spines of the fish may result in pain, swelling, numbness and sometimes more severe effects including paralysis and systemic
Reports of lionfish in the Gray's Reef National Marine Sanctuary were confirmed in 2007, and since that
time, lionfish also invaded the Florida Keys National Marine Sanctuary in 2009 and the Flower Garden Banks National Marine
Sanctuary in the Gulf of Mexico in 2011. NOAA's Office of National Marine Sanctuaries is tracking lionfish activity in and
around Gray's Reef, Florida Keys, and the Flower Garden Banks National Marine Sanctuaries. Although lionfish have only been seen inside Gray's Reef on two occasions, it is expected that the number will increase over time.
Eradication of introduced invasive species is difficult and often impossible, and management practices focus largely on prevention of introductions. However, once an invasive species is established, an early detection and rapid
response (ED/RR) monitoring program may help manage the invasion.
Todd Recicar, GRNMS, and lionfish at US Navy R2 Tower.
(Photo: Greg McFall, GRNMS)
As part of the effort to increase detection, reporting and response, researches will be conducting
fish surveys and looking for lionfish on all dives within the sanctuary. Researchers will also be traveling outside the
sanctuary to look for lionfish in areas where the invaders are consistently seen. When lionfish are observed, researchers
will be photographing and documenting their location, as well as using specific collecting and handling techniques in an
effort to successfully remove lionfish from sanctuary waters. Lionfish observations will be sent to USGS, as well as added to the sanctuary lionfish database. After removal, lionfish will be measured, weighed, and necropsied so their gut contents can
be analyzed to determine what species of fish they are eating in and around sanctuary waters. Fish surveys will be analyzed to determine if there are less reef fish and crypic species in areas where lionfish are observed versus areas where they are
not to determine if these species are being eaten (in correlation with the gut content analysis). This information will help
researchers understand the impacts these invaders may be having on the sanctuary.
As the sanctuary continues to monitor lionfish, the diving and fishing public is encouraged to report sightings and locations
of lionfish to the sanctuary office by phone or email. The information will be used to track the progress and impacts of the
invasion, and enable responders to focus their removal efforts.