Recent news reports from Texas to Jamaica to the Bahamas have documented the rapid spread of the lionfish—an invasive marine species. Lionfish have quickly become established across the waters of the southeastern U.S. and the Caribbean. New sightings abound—earlier this month lionfish reached the Flower Garden Banks National Marine Sanctuary off the coasts of Texas and Louisiana. Because of their role in upsetting the ecological balance of coral reef ecosystems, the rapid growth in the populations of these fish poses a grave threat to the region’s coral reefs. Consequently, the region’s fishing and tourism industries, which depend on coral reefs, may also be at risk. Governments across the region are trying to respond to the lionfish invasion by developing new campaigns and cooperation strategies that could pose important lessons for how to deal with invasive marine species in the future.
Two species of lionfish (Pterois volitans and P. miles) are responsible for this recent and growing threat to Atlantic and Caribbean reefs. Native to the Indo-Pacific, these species’ colorful and dramatic appearance make them popular ornamental fishes in saltwater aquariums (see photo above). Though no one is certain how or when the lionfish invasion began, strong evidence suggests that people first introduced lionfish to the Atlantic along the southeastern coast of Florida, where they were first sighted in 1985. By 2001, people reported sightings in waters off the coasts of Georgia, the Carolinas, and Bermuda. Over the last decade, lionfish population densities have increased in these areas and these species have spread southward, and are now established throughout much of the Caribbean (see slideshow below). Lionfish are now invading the Gulf of Mexico and the northern coast of South America. These fish pose a serious threat to reef fish populations across the region, and thus to coral reef ecosystems and the people who depend on them.
In the Caribbean, more than 75 percent of coral reefs are already threatened by a combination of overfishing, pollution from land and sea, and coastal development. Overfishing, the most pervasive threat to Caribbean reefs, has already devastated populations of many large predators such as groupers and snappers. On some reefs even herbivorous fish populations have been greatly reduced. As populations of herbivorous fish have declined, the health of coral reefs has been negatively impacted by the growth of algae on the reefs. Other threats, including disease, hurricanes and coral bleaching, further add to the pressure on the region’s coral reefs. An unchecked lionfish invasion, on top of these threats, could possibly lead to irreversible changes to Caribbean reef ecosystems, including further reductions in forage (prey) fish species, competition with predator fish species, and increased algal growth and degradation of reefs due to the reduction in herbivorous fish.
In a region where more than 42 million people are very dependent on coral reefs for food and livelihoods, the lionfish invasion could have serious socioeconomic implications. Commercial and subsistence fisheries may suffer losses as lionfish either prey on economically important species (such as snapper and grouper) or compete with those species for food. Lionfish could even impact the Caribbean’s $2.1 billion dive tourism industry, as they have the potential to greatly reduce the diversity (and thus the attraction) of the reef ecosystem. Divers, swimmers and fishermen are also at risk of being stung by the venomous lionfish.
Governments across the region are developing lionfish management plans, hoping to bring lionfish populations back to a level where they no longer impact other fisheries.
Going forward, it will be critical to learn as much as possible from the lionfish invasion to prevent future invasions before they reach such critical levels. Early detection and rapid response programs, increased awareness of invasive species and their impacts, species risk assessments and increased regulation of the aquarium trade could all help reduce the risk of future invasions in the marine environment.
Many thanks to: James Morris (NOAA) for providing up-to-date information; Amy Benson (U.S. Geological Survey) for providing the latest maps; and Lloyd Gamble (U.S. Department of State), Mark Spalding (TNC), and Paula Whitfield (NOAA) for reviewing this story.
Morris, J. A. 2011. “Invasive Lionfish Facts.” Silver Spring, MD: NOAA National Centers for Coastal Ocean Science. ↩