By John Dawes

The first report of the popular Indo-Pacific lionfish existing along the coast of Florida (off Palm Beach, Boca Raton and Miami) dates back to 1992. Several years later, further reports followed from Bermuda, Georgia, North and South Carolina, and more recent sightings extend their range as far as New York (though these waters are deemed too cold for the species to survive during winter), the Cayman Islands, Jamaica and the Dominican Republic, to name but a few non-native locations.

Pterois volitans…or is it P. miles? Credit: John Dawes

To date, all reports have referred to these lionfish as belonging to the species Pterois volitans. However, genetic analyses carried out in 2007 revealed that there are two species, rather than one: P. volitans (the red, common or peacock lionfish, turkeyfish, firefish or butterfly cod)  and P. miles (variously known as the devil’s firefish, soldier lionfish or Indian turkeyfish). According to the report, both species have been introduced along the eastern U.S. coast, with approximately 93 percent of these introductions consisting of P. volitans. These findings were recorded in 2008 by James A. Morris Jnr., J.L. Akins, A. Barse, D. Cerino, D.W. Freshwater, S.J. Green, R.C. Muñoz, C. Paris and P.E. Whitfield in “Biology and Ecology of the Invasive Lionfishes, Pterois miles and Pterois volitans: Proceedings of the 61st Gulf and Caribbean Fisheries Institute.”

Because these stocks exhibit low genetic diversity, they could evolve along different lines to their more widely and naturally distributed counterparts. This could then result in these exotics developing different morphological and genetic characteristics, which could eventually result in new species.

Studies to estimate lionfish densities in their non-native waters have been under way for several years now. In 2004, for example, it was estimated that there were about 21 fish per hectare in 17 locations studied off North Carolina. Figures more than 18 times higher were obtained off New Providence in the Bahamas in 2008—“more than eight times higher than estimates from their native range.” There is, however, some uncertainty over this last estimate, since few data are available from lionfish home-range waters.

Dispersal ability is considered to be high among alien lionfish, largely owing to their method of reproduction. This includes the production of floating egg masses by females. These disintegrate within a few days, releasing planktonic larvae, which remain as such for 25-40 days and can be spread by currents. Morris conclude that “lionfish establishment along the southern edges of Central America (Nicaragua, Costa Rica and Panama), the Yucatán Peninsula and the Western Gulf of Mexico is likely within a few years or less.”

Data regarding the ecological impact of exotic lionfish are scant, although some do exist and several studies are under way. In 2008, one such study reported that, during a dive week observation period, there was a “79 percent reduction in forage fish recruitment on experimental patch reefs.” However, detailed knowledge of lionfish impact is still lacking and the effect that high lionfish densities can or will have on the tourist industry is not known.

Morris’ paper refers to prevention as being “the least expensive and most effective management option.” However, since lionfish are already present, prevention programs can only aim at eliminating or minimising potential future releases. Most programs currently involve removing lionfish (by netting or spear fishing), culling, promoting lionfish as food fish and supporting “adopt a reef” programs to encourage local citizens “to take ownership of small reefs and to protect them from lionfish impacts.” Our industry can continue to do its part by spreading the message that no species (not just lionfish) must be released into non-native waters. <HOME>