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The first documented capture of a lionfish within the Atlantic Ocean occurred in 1985 near Dania Florida (Morris and Atkins, 2009). While it has often been reported that the lion fish invasion is tied to an accidental release of six to eight lionfish from an aquarium during Hurricane Andrew, Walter Courtenay was quoted in 2010 as saying he would like to "put this idea to rest". In 1995, Courtenay was one of the first to make a connection between lionfish and Hurricane Andrew (Courtenay, 1995). Years later Courtenay now describes his original report: "It was second-hand information, which unfortunately continues to spread, so that Andrew is often mentioned as the reason for the catastrophic lion fish invasion" (Morell, 2010). The most probable explanation for the invasion of the lionfish in the Atlantic Ocean remains the aquarium trade but the Hurricane Andrew release as the source of the invasion has since been refuted by one of the original reporters.
In January 2010 during the general assembly of the International Coral Reef Initiative (ICRI), the Secretariat agreed to set up an Ad Hoc Committee to develop a strategic plan for the control of lionfish in the Wider Caribbean. This committee organized a regional workshop at Cancun, Mexico, on August 25-27, 2010, with a view to develop a strategy for the prevention, control, and management of Lionfish (Pterois sp.) in the Wider Caribbean. A summary of the workshop may be found at:
The IndoPacific lionfish invasion of the
U.S. south Atlantic sea coast and Caribbean Sea
Lionfishes are venomous species of scorpionfishes which are native to IndoPacific and oceanic coral reef ecosystems and adjacent habitats. Because of their colorful and dramatic appearance, they are prized by aquarists around the world. Through accidental and purposeful release into warm Atlantic waters, they have become established as voracious alien species that pose a serious threat to coral reefs in Bermuda, the American tropics of Florida, the Gulf of Mexico, the Caribbean islands, Central America, and northern South America.
The participants in this discussion were concerned with the sources of introduction of lionfishes into the Atlantic Ocean, the increased number of sightings of at least two species of lionfishes in various locations, the nature of threats posed by these fishes to Atlantic coral reefs, and what protective or control measures could be applied to reduce these threats.
Click here for a listing of discussion participants
Click here to download the complete unedited discussion (pdf, 101 KB)
Introduction and Background
In addition to natural and anthropogenic threats and stressors to coral reefs (e.g., coral bleaching, pollution, development, sedimentation, overfishing, disease, habitat alteration, ocean acidification, violent storms, etc.), the recent invasion and establishment of two sibling species of voracious and predatory lionfishes – the red lionfish (Pterois volitans), which has been most heavily sighted in the Atlanic, and the devil firefish (Pterois miles) – pose a major new threat to south Atlantic and Caribbean coral reefs.
Lionfishes possess a stunning appearance. They have distinctive brown, red, maroon, and white stripes or bands covering the head and body. Fleshy tentacles are located above their eyes and below the mouth. They have fan-like pectoral fins and separated dorsal, pelvic, and anal spines, each of which is capable of delivering a venomous, painful puncture wound.
A red lionfish (Pterois volitans) photographed in the Atlantic Ocean (NOAA photo)
Lionfishes are now established off of the Atlantic Coast of the United States from Florida to Cape Hatteras, North Carolina. Juvenile lionfish have been found in near-shore waters off New York, New Jersey,and Rhode Island since 2001; however survival of these fish is not expected due to cold winter temperatures. The northward transport of lionfish eggs and larvae by the Gulf Stream has most likely enhanced dispersal of lionfishes along the Atlantic coast. In addition, lionfishes have become established in Bermuda, the Bahamas, Columbia, Cuba, the Dominican Republic, Jamaica, Puerto Rico, Turks and Caicos, and the Cayman Islands. There are also reported sightings in Belize, Haiti, U.S. Virgin Islands, Mexico, and Aruba, Curacao, and Bonaire.
The most probable explanation for the invasion of the lionfish in the Atlantic Ocean is the aquarium trade. Other proposed explanations include the transport of lionfishes, during one or more of their life stages, in the ballast water of ships traveling from the Pacific Ocean, although this scenario does not hold much credence among experts. In 1992, at least six lionfish from a beachside aquarium were accidentally released into Biscayne Bay during Hurricane Andrew, although lionfish sightings have been reported prior to 1992. The present populations of red lionfish are probably the descendents of these fish and others released accidentally or purposely into the warm South Atlantic waters.
Lionfishes have the potential to disrupt coral reef community population structure and dynamics. Not only are they voracious predators that out-compete many other species for food resources, but they also have few known natural predators of their own. Their diet consists of numerous shrimp, crabs, and other crustaceans, including juveniles of the commercially important spiny lobster (Panulirus argus). Lionfish are also responsible for great reductions in fish numbers on reefs where they become established. They prey on herbivorous fishes that consume macroalgae and help protect corals from algal overgrowth. In addition, cannibalism is not unknown among lionfishes. To feed, lionfishes often use their wide-spread pectoral fins to herd and trap their prey in corners or against walls and then swallow them with one vacuum-creating movement of their jaws.
The red lionfish, a member of the scorpionfish family, is known by many names, including lionfish, turkeyfish, zebrafish, butterfly cod, ornate butterfly cod, peacock lionfish, and red firefish. It is more easily identified than other lionfishes because it is widely distributed, stands out in its habitat with its bizarre appearance and coloration, and has been documented to be dangerous to humans because of its venomous sting. Venom glands at the base of the dorsal, pelvic, and anal fin spines produce neurotoxins that are injected into a potential predator. Penetration of the spines delivers an extremely painful but usually non-fatal envenomation which however, should be treated as a serious medical emergency.
The red lionfish is widely distributed throughout the western Pacific from southern Japan to Micronesia, Australia and the Philippines. P. volitans occurs throughout most of Oceania (including the Marshall Islands, New Caledonia, and Fiji) east to French Polynesia. The closely related species, the devil firefish (P. miles), is found primarily in the Indian Ocean, Red Sea, and eastward to Sumatra. Typically, these fishes inhabit lagoons, rocky ledges or crevices, caves, and coral reefs to depths exceeding 150 meters. However, they also have been sighted in estuaries, bays, and harbors, where they may have been introduced via ballast water, although this scenario does not hold much credence among experts.
After courtship and spawning, the planktonic eggs and larvae of lionfishes are dispersed over wide areas. A particular issue in controlling their numbers is their huge reproductive potential and age of reproductive maturity. NOAA researchers have determined that lionfish reach sexual maturity within two years and spawn multiple times during the spawning season, which may be year round. Each spawn can produce up to 30,000 eggs. Unfortunately, scientists have concluded that the red lionfish populations will continue to grow and cannot be extirpated using conventional methods. Due to their fecundity, rapid and wide-spread distribution, adaptability to a variety of shallow and deep habitats, and behavior, scientists believe the lionfish invasion could become the most disastrous in history, devastating coral reef ecosystems throughout the Americas.
Synopsis of Participant discussions
Impact on coral reef ecosystems
A lionfish spreading its fins herding and trapping prey fishes
Lionfish experts are in agreement that invasive lionfish populations will continue to grow and cannot be eliminated using conventional methods. Lionfishes have become established along the southeastern coast of the United States, Bermuda, the Bahamas, and throughout the Caribbean. This places swimmers, snorkelers, divers, and fishermen at risk from their painful, venomous sting and leaves native reef fish populations and coral reef community stability at great risk from their interactions with this species. In a five-week experiment, scientists in the Bahamas established that lionfish can cause significant reductions (by 79%) in the recruitment of native fishes. One large lionfish was observed consuming 20 small fishes in a 30-minute period.
Lionfishes may, directly and indirectly, cause harm to coral reef ecosystems. As aggressive ambush predators with few predators of their own in their introduced range, lionfishes can quickly and alarmingly reduce local native reef fish (and some invertebrate) populations to the point where native piscivores cannot compete for these prey animals. This in-turn can cause a reduction in the growth and survival of the native predators. Stomach content analyses of lionfishes reveal a wide diversity in prey species and size classes. As stated by one participant in the discussion, lionfishes are eating nearly anything that will fit into their mouths.
Most lionfish prey on crustaceans and small-bodied forage fishes, including commercially and recreationally important snappers and groupers. Compared to total local reef biomass, lionfishes consume a considerable amount of prey biomass from the reef. In addition, experiments have shown that native reef fish may avoid feeding on juvenile lionfish, probably because of their venomous defense apparatus. There is great concern about the effect of the invaders on commercial and recreational fisheries. Since lionfishes feed on smaller fishes that are usually consumed by groupers and other native fishes, their existence could negatively affect the food chain of many commercial and other species. As one NOAA coral reef manager in North Carolina stated, "our biggest concern is how they impact the economic value of the shelf reef ecosystem. There may be reduced economic returns from commercial fisheries. The economic value of heavily impacted and devastated reefs may be reduced also as recreational divers and snorkelers stop visiting, and perhaps causing a major collapse of the local tourist industry. Recreational and commercial value of reef-related pelagic and benthic species is close to a half-billion dollars each year to the Carolinas."
As lionfish colonize more territory in the Caribbean, they can have a devastating effect on coral reefs already stressed by climate change, pollution, disease, overfishing, sedimentation, and other stressors.
Sightings and Dispersal
Lionfishes were first reported in Atlantic waters in the 1990s and have since become established along the U.S. east coast from Florida through North Carolina and east to Bermuda. They are also regular inhabitants throughout the Bahamas and Caribbean nations. They have been sighted as far south as Colombia and the Netherlands Antilles and as far east as the U.S. Virgin Islands. Their expansion has been extremely rapid and even exponential in scope.
Distribution of lionfish in the Atlantic Ocean in 2009
A NOAA flyer requesting information on lionfishes from divers
One of the topics discussed by participants related to whether any solid hypotheses existed explaining how lionfishes spread throughout the coastal United States and Caribbean. Through DNA analysis, scientists now believe the initial population of lionfish, which contained at least 10 females and was comprised of two species, Pterois volitans and Pterois miles, established itself in the western Atlantic waters of the Key Biscayne region. It is surmised that the eggs and larvae of this population were then carried northward in the warm waters of the Gulf Stream to different destinations, which most likely explains the lionfish sightings in New York and New England. It still remains a mystery, however, as to how lionfish populations exploded so rapidly and spread over large distances as far westward as Bermuda and southward to Colombia and Aruba. A question was posed as to whether a lionfish is such a strong swimmer that it could traverse large expanses of open water to Bermuda. (There has been reported sightings of lionfishes swimming in open waters off the east coast midway to Bermuda.) Another participant inquired whether regional water current pathways match the chronologies of lionfish sightings across the Caribbean.
Can dispersal of young lionfishes be aided by rafting? Is there DNA sequencing evidence to suggest that the invasive populations are related to the “founder” population in Key Biscayne? Or does the evidence suggest multiple releases by aquarists in the U.S. and Caribbean nations “who can’t be bothered to kill or return their pets to the pet shop?" Understanding how lionfish populations have been expanding and spreading so widely and quickly may help identify ways to slow its dispersal or at least prevent expansions of its range to Brazil and west African coasts.
In 2004, NOAA scientists collected 28 lionfish on one shipwreck off the coast of North Carolina during a single dive. Twenty five more were collected later at this same location. (Photo credit: Christine Addison)
Local experts in Puerto Rico reported sightings of lionfishes in both eastern and western coastal waters of the island during the daytime, which prompted one participant to inquire whether sightings included night-time censuses. (This participant would typically see more lionfishes while diving at night in Palau.) Another reported sighting was in Roatan, one of the islands in the Bay of Honduras. The Cayman Islands Government reported captures and sightings of significant numbers in Grand Cayman, Little Cayman, and Cayman Brac, from depths ranging from about one meter to 34 meters on all sides of the islands and in many different habitats. First reports of lionfishes in Cuba were in June 2007. The first observations from the Turks and Caicos (South Caicos) were also in 2007, when 23 individuals were observed in depths shallower than eight feet (2.4 meters) in habitats as diverse as patch reef, mangrove, seagrass, and deep reef. In January 2009, the first confirmed lionfish was reported and captured in the Florida Keys National Marine Sanctuary. Additionally, lionfishes were sighted in the Bay of Granate, Colombia on May 13, 2009.
Lionfishes adapt to many different habitats. In the Bahamas, they have been found at depths ranging from about four feet (1.2 meters) to more than 450 feet (137 meters) on reef walls, patch reefs, rocky areas, hard bottom with ledges and crevices, mangrove creeks, isolated coral heads, blue holes, ship wrecks, man-made structures, and various debris collections. One participant described them as “habitat generalists,” as they require only a habitat that provides shade and a surface against which to trap their prey. Another participant observed that lionfishes in Sri Lanka are more likely to be found on rocky reefs rather than coral formations, while juveniles are common in estuaries.
Education, Research, and Communication
A diver tracks a lionfish in a seagrass meadow
Some locations are now working to develop local lionfish response plans. To assist with this development, the Reef Environmental Education Foundation (REEF) has partnered with NOAA, USGS, and Simon Fraser University to hold lionfish workshops focused on educating local managers, dive operators, and fishermen about the current state of knowledge and ongoing lionfish research, potential solutions available for addressing the invasion, early grace detection and rapid response strategies, handling techniques, proposed legal changes related to lionfish collection, and local market development initiatives. Workshops have been conducted in the Bahamas with more than 40 representatives from government agencies and non-governmental organizations, in the Turks and Caicos Islands, NOAA’s Florida Keys National Marine Sanctuary, and elsewhere. REEF's critical research and education efforts on the invasion of the lionfish into Atlantic and Caribbean waters have been featured in several news stories, publications, and video media.
Scientists at NOAA’s Center for Coastal Fisheries and Habitat Research in Beaufort, North Carolina and others working in the South Atlantic Bight have taken lead roles in addressing the status and impacts of lionfishes along the U.S. east coast. Research on lionfish reproductive biology, age/growth studies, predatory relationships, population dynamics, parasites and diseases, genetics, and more has been published recently or is being reviewed for publication. Other scientists from Simon Fraser University, the University of British Columbia, and Oregon State University have been studying similar issues and impacts in the Bahamas and areas of the Caribbean Sea.
The U.S. Geological Survey (USGS) maintains a database of nonindigenous aquatic species (NAS), including lionfish sightings. The USGS also has developed mapping tools and an early warning alert system for lionfish sightings in new locations.
Lionfish Population Control
The participants agree that it is unlikely that the lionfish invasion can be reversed. Due to their extensive geographical range and diversity of habitats and depths they occupy, any major attempts to eradicate existing lionfish populations would be impractical and doomed to failure. Control is now the only option left. Possible control measures that have been considered include recovering and maintaining native populations of predators, such as large groupers, sharks, and others that prey on lionfish eggs, larvae, and juveniles. A participant noted that in Palau, locations with high numbers of large and medium-sized groupers also had low numbers of lionfish. Other measure to control the lionfish population explosion include killing those lionfishes that are easily spotted and captured; controlling the aquarium trade in lionfishes in the Americas; encouraging a lionfish fishery for human consumption and other commercial uses, such as harvesting for the aquarium trade; reducing fishing pressure on native competitors that occupy the same ecological niche; and biological control (although no specifics were offered).
A participant reflected upon missed opportunities to set up a coordinated observation network in the Caribbean during the mass mortality of the long-spined sea urchin, Diadema antillarum, in 1983-84. He suggested that now is the time to use “our superb and ubiquitous” skills in communication to establish a coordinated observation/communication network to determine the impact of lionfishes on populations of small reef fishes. Eradication, he feels, is not a workable solution to the invasion in the Caribbean. He thought it best to anticipate the future of Caribbean reefs with established populations of lionfishes. He recommended that scientists and managers continue to collect data and develop measures to control the expansion of lionfish populations, while also identifying and reducing the negative impacts of established populations on different marine communities in the Caribbean.
Another participant stated that while complete eradication is not an option, control efforts, such as culling lionfishes from coral reefs, are vital to limit the impacts on local reef communities which are already stressed. REEF trained and licensed over 160 dive professionals in the Cayman Islands alone to respond to lionfish sightings and remove them using early detection and rapid response protocols. The use of volunteer divers in early detection and response may help to slow the spread of lionfishes and control populations at key high-priority locations. Another participant was skeptical that volunteer collectors’ efforts at manual removal of lionfishes would achieve anything other than a “highly localized effect at few sites,” noting that the aquarium trade in the Pacific has not resulted in any reduction of lionfish numbers on their native reefs where their natural predators exist.
Another participant noted that the lionfish invasion story might have a silver lining compared with the devastating effects in the Mediterranean of an “escaped” invasive species of seaweed, Caulerpa taxifoliaused to decorate saltwater aquariums. It "escaped" from human control in the 1980s and has spread like a cancer throughout the Mediterranean, overwhelming native species and habitats. However, with adequate coordination, both removal of lionfish individuals (aimed at containment and control) and study of this organism (aimed at how the Caribbean will survive with a controlled lionfish population), we may diminish or control the disastrous effects of lionfishes on Caribbean reef fauna. If nothing is done, however, there may not be much of a future for Caribbean reef communities.
Several participants also suggested that a special fishery might be possible to help control lionfish populations. Although it requires careful harvesting, lionfishes “make wonderful sushi and cerviche.” They also are excellent when eaten fried whole or filleted. There are websites that provide recipes and techniques for harvesting and preparing lionfishes for edible consumption. The Bahamas Reef Environmental Educational Foundation (BREEF) encourages the consumption of lionfish and has been actively promoting the capture, safe handling, cleaning, and preparation for the table. One participant noted that while lionfishes have been exploited as a food fish in some areas, he has no information of any noticeable decline in their population numbers.
Threats to humans
The venomous spines of a lionfish
Another subject of discussion concerned the treatment of lionfish stings. The first response is to immerse the affected part in hot water for about 30 minutes. Lionfish toxins, which are proteinaceous in nature, are degraded and denatured by heat. Hospital treatment is then used to decrease the pain and monitor for systemic and allergic reactions. Medical analgesia, removal of spines, administration of prophylactic antibiotics, and tetanus immunization are the mainstays of treatment. A lionfish sting is usually non-fatal but in extreme cases could lead to allergic reactions, nausea, vomiting, and cardiovascular events.
Lionfish spines are not like hypodermic syringes or pit viper fangs, i.e., they are not hollow with venom sacks located at the base. Instead, a loose integumentary sheath covers each spine and during envenomation, the sheath is pushed down the spine, causing compression of two venom glands located at the base. The neurotoxic venom then travels from the glands through depressions (grooves) in the wall of the spine and into the puncture wound. There have been at least four toxins identified: an antigenic heat-labile protein (the primary toxin); acetylcholine (a neurotransmitter); a neuromuscular toxin; and a low molecular weight non-proteinaceous ichthyotoxin.
Future possible range extension of the lionfish
Potential future range of lionfish based on the lethal thermal minimum of
10°C (Morris J.A. 2009).
Assuming that lionfishes in the southeast U.S. coastal waters and Caribbean are here to stay and that their numbers will increase, the future potential range of these fishes can be predicted based on survivable minimum bottom temperatures. Morris (2009) presented a map (below) that shows the potential range of lionfishes encompassing the U. S. south Atlantic coast, Gulf of Mexico, Caribbean Sea, and South America from Colombia to southern Brazil.
Albins, M.A. and M.A. Hixon. 2008. Invasive Indo-Pacific lionfish (Pterois volitans) reduce recruitment of Atlantic coral-reef fishes. Marine Ecology Progress Series 367: 233-238.
Courtenay, W.R.. 1995. Marine fish introductions in south-eastern Florida. American Fisheries Society Introduced Fish Section Newsletter.
Morrel, V. 2010. Mystery of the Lionfish: Don't Blame Hurricane Andrew. Science Insider. http://news.sciencemag.org/scienceinsider/2010/04/mystery-of-the-lionfish-dont-bla.html
Morris Jr., J.A. The Biology and Ecology of the Invasive Indo-Pacific Lionfish. [doctoral dissertation]. [Raleigh (NC)]: North Carolina State University; 2009. 168pp.
Morris, Jr., J.A., J.L. Akins, A. Barse, D. Cerino, D. W. Freshwater, S J. Green, R. C. Muñoz, C. Paris, and P.E. Whitfield. 2008. Biology and Ecology of the Invasive Lionfishes Pterois miles and Pterois volitans. Proceedings of the 61st Gulf and Caribbean Fisheries Institute, Gosier, Guadeloupe, French West Indies, November 10-14, 2008.
Morris Jr., J.A. and J. L. Akins. 2008. Feeding Ecology of Invasive Lionfish (Pterois volitans) in the Bahamian Archipelago. Proceedings of the 61st Gulf and Caribbean Fisheries Institute, Gosier, Guadeloupe, French West Indies, November 10-14, 2008.
Morris Jr., J.A. and J. L. Akins. 2009. Feeding ecology of invasive lionfish (Pterois volitans) in the Bahamian archipelago. Environmental Biology of Fishes. 86(3): 389-398. doi: 10.1007/s10641-009-9538-8.
NOAA Ocean Service Education
Nonindigenous Aquatic Species (NAS) Fact Sheet