Pterois is a genus of venomous marine fish, commonly known as lionfish, native to the Indo-Pacific. Also called zebrafish, firefish, turkeyfish, tastyfish or butterfly-cod, it is characterized by conspicuous warning coloration with red, white, creamy, or black bands, showy pectoral fins, and venomous spiky fin rays. Pterois radiata, Pterois volitans, and Pterois miles are the most commonly studied species in the genus. Pterois species are popular aquarium fish. P. volitans and P. miles are a recent and significant invasive species in the west Atlantic, Caribbean Sea and Mediterranean Sea.
Two of the twelve species of Pterois, the red lionfish (P. volitans) and the common lionfish (P. miles), have established themselves as significant invasive species off the East Coast of the United States and in the Caribbean. About 93% of the invasive population in the Western Atlantic is P. volitans. They have been described as "one of the most aggressively invasive species on the planet".
The red lionfish is found off the East Coast and Gulf Coast of the United States and in the Caribbean Sea, and was likely first introduced off the Florida coast by the early to mid-1990s. This introduction may have occurred in 1992 when Hurricane Andrew destroyed an aquarium in southern Florida, releasing six lionfish into Biscayne Bay. However, a lionfish was discovered off the coast of Dania Beach, south Florida, as early as 1985, before Hurricane Andrew. The lionfish resemble those of the Philippines, implicating the aquarium trade. The lionfish may have been purposely discarded by unsatisfied aquarium enthusiasts. This is in part because lionfish require an experienced aquarist, but are often sold to novices who find their care too difficult. In 2001, NOAA documented several sightings of lionfish off the coast of Florida, Georgia, South Carolina, North Carolina, Bermuda, and Delaware. In August 2014, when the Gulf Stream was discharging into the mouth of the Delaware Bay, two lionfish were caught by a surf fisherman off the ocean side shore of Cape Henlopen State Park: one red one that weighed 1 pound 4.5 ounces and one common one that weighed 1 pound 2 ounces. Three days later a 1-pound 3 ounce red lionfish was caught off the shore of Broadkill Beach which is in the Delaware Bay approximately 15 miles north of Cape Henlopen State Park. Lionfish were first detected in the Bahamas in 2004. In June 2013 lionfish were discovered as far east as Barbados, and as far south as the Los Roques Archipelago and many Venezuelan continental beaches. Lionfish were first sighted in Brazilian waters in late 2014. Genetic testing on a single captured individual revealed that it was related to the populations found in the Caribbean, suggesting larval dispersal rather than an intentional release.
Adult lionfish specimens are now found along the United States East Coast from Cape Hatteras, North Carolina, to Florida, and along the Gulf Coast to Texas. They are also found off Bermuda, the Bahamas, and throughout the Caribbean, including the Turks and Caicos, Haiti, Cuba, the Dominican Republic, the Cayman Islands, Aruba, Curacao, Trinidad and Tobago, Bonaire, Puerto Rico, St. Croix, Belize, Honduras, and Mexico. Population densities continue to increase in the invaded areas, resulting in a population boom of up to 700% in some areas between 2004 and 2008.
Extreme temperatures present geographical constraints in the distribution of aquatic species, indicating temperature tolerance plays a role in the lionfish’s survival, reproduction, and range of distribution. The abrupt differences in water temperatures north and south of Cape Hatteras directly correlate with the abundance and distribution of Pterois. Pterois expanded along the southeastern coast of the United States and occupied thermal-appropriate zones within 10 years, and the shoreward expansion of this thermally appropriate habitat is expected in coming decades as winter water temperatures warm in response to anthropogenic climate change. Although the timeline of observations points to the east coast of Florida as the initial source of the western Atlantic invasion, the relationship of the United States East Coast and Bahamian lionfish invasion is uncertain. Lionfish can tolerate a minimum salinity of 5 parts per thousand and even withstand pulses of freshwater, which means they can also be found in estuaries of freshwater rivers.
The lionfish invasion is considered to be one of the most serious recent threats to Caribbean and Florida coral reef ecosystems. To help address the pervasive problem, in 2015 National Oceanic and Atmospheric Administration (NOAA) partnered with the Gulf and Caribbean Fisheries Institute to set up a lionfish portal to provide scientifically accurate information on the invasion and its impacts. The lionfish web portal is aimed at all those involved and affected, including coastal managers, educators and the public and the portal was designed as a source of training videos, fact sheets, examples of management plans, and guidelines for monitoring. The web portal draws on the expertise of NOAA's own scientists as well as other scientists and policy makers from academia NGO and managers.