Invasive Lionfish

A single lionfish hovering above the reef at Flower Garden Banks National Marine Sanctuary
Invasive lionfish first reached the sanctuary in 2011 (Image: FGBNMS/Schmahl)

Lionfish (Pterois volitans, Pterois miles), venomous fishes native to the Indo-Pacific and Red Sea, are the first invasive species of fish to establish themselves in the Western Atlantic (Schofield 2009).

Although they are quite beautiful, they are also skilled predators capable of eating any fish or invertebrate that will fit in their gaping mouths, and they have venomous spines that can cause serious injury to people.

The Invasion

The first lionfish recorded in the Western Atlantic (east coast of the United States, Caribbean Sea and Gulf of Mexico) was a specimen captured near Dania, Florida in 1985. No other lionfish sightings were reported until 1992. The most likely source of these fish was the home aquarium trade.

Map of the eastern U.S. and Mexico, Gulf of Mexico, Central America, Caribbean and northern South America with red dots showing locations of lionfish sightings in 2003
Click on this map to see an animated version of the spread of lionfish in the Tropical Western Atlantic from 1985 forward.

At first, the spread of the lionfish population was rather gradual, but in 2000 the number of sightings began to increase exponentially. By 2009, lionfish were pretty well established along the Atlantic coast and throughout the Caribbean.

In 2010, sightings were also recorded in the northwestern Gulf of Mexico, along the coasts of Alabama, Mississippi and Louisiana. In July 2011, the first lionfish was observed in the sanctuary, at Stetson Bank.

Lionfish on a rocky reef at Sonnier Bank
A lionfish at Sonnier Bank in 2010.

By the end of 2015, over 2,600 lionfish were observed within the sanctuary. About 1,500 of those were successfully removed and analyzed for important data.

Lionfish Observed and Removed in FGBNMS
 Year  Stetson Bank  East Flower Garden Bank  West Flower Garden Bank
 2011 11 
 2012 30  40  105 
 2013 89  172  265 
 2014 32  232  363 
 2015 112  437  720 
 2016 116  325  288 
 2017 14  44  35 
 Lionfish Totals 404  1247  1774 


Graph of Lionfish Observations table data showing rise in number of lionfish at all three banks from 2010-2015 then steady drops through 2017
Trends in lionfish sightings at all three banks since 2010.

The Problems

Lionfish are indiscriminate eaters. If it fits in their mouths, they will eat it! This includes many smaller species of fish and invertebrates that are important herbivores, keeping algae in check on the reef. It also includes the young of commercially important fish species, such as snapper and grouper. Not only can this affect the ecological balance of the reef system, but it may also impact fisheries.

Lionfish with mouth wide open and fins flared
Lionfish gulp their food whole and will eat anything that fits inside their gaping mouths. (Image: FGBNMS/A. Sterne)

Lionfish have 18 venomous spines. Thirteen spines are found at the front of the dorsal fin, two at the front edge of each pelvic fin, and one at the front edge of the anal fin. An encounter with a lionfish can have painful consequences for people and potential predators.

Lionfish reproduce year round. Mature females (>1 year old) release 50,000 eggs every three days for the rest of their lives. Most reef fishes only spawn once a year, so lionfish may quickly outnumber native fish populations.

Lionfish have no natural predators in their invasive range. We're not entirely certain what eats lionfish in their native range, but it's most likely large predators like grouper, snapper, eels and sharks. We're hopeful that the same predator groups here will some day figure out that they can eat lionfish, but that won't happen quickly and it won't help in areas that have already been overfished.

A headless lionfish carcass on a cutting board next to 15 small fish that were taken out of its stomach
Small fishes fall easy prey to lionfish. All of these were eaten by one lionfish at about the same time. (Image: FGBNMS/Drinnen)

Lionfish aren't recognized as predators. This is known as prey naivete and results in native fish and invertebrates not knowing to avoid lionfish to keep from being eaten.

The Response

Experts say it is unlikely that we will ever be able to completely eliminate lionfish from the Western Atlantic. So, the objective now is to minimize their impact on sanctuary resources. At this time, sanctuary policy is to remove any lionfish encountered. Research has shown that targeted removals in localized areas can be an effective control mechanism.

Most of the lionfish removed from the sanctuary are dissected and evaluated as part of ongoing research to learn more about invasive lionfish populations.

Two divers spearing lionfish on the reef
Researchers Emma Hickerson (left) and Marissa Nuttall remove two invasive lionfish using small pole spears. (Image: FGBNMS/Schmahl)

Permits for lionfish removals have been issued to a recreational dive charter that frequents the sanctuary to assist us in this effort. Permits are also issued for the annual, sanctuary-managed Lionfish Invitational, a derby-like event that allows recreational divers to assist in a mass removal and survey effort.

Without appropriate permits, sanctuary regulations only allow for removal of lionfish by traditional hook and line fishing methods.

What You Can Do

1. Make sure you aren't part of the problem. DO NOT release non-native species of any kind into your local ecosystem. Not all will survive, but those that do become established can wreak havoc. Lionfish are just one example.

2. Participate in removal events in places where they occur. Derbies are hosted at regular intervals in the Florida Keys and many other Caribbean locations. FGBNMS hosts more structured Lionfish Invitationals that also serve to collect important scientific information.

3. Spread the word!