New research confirms increase in population density of invasive Lionfish
This story entered on 6th Oct, 2005 06:14:39 AM PST

In August 2004, NURP’s Center for the Southeast U.S. and Gulf of Mexico at the University of North Carolina at Wilmington and NOAA Ocean & Coasts’ NCCOS Center in Beaufort, NC, reported the sudden growth in the population of invasive lionfish (Pterois volitans) off the southeastern U.S. coasts, from Florida to Cape Hatteras. In this article, the extent and density of these invasive fishes is better defined as the result of research undertaken in 2004 and 2005 within the context of a specific area in North Carolina. The invasion of the lionfish is deemed a matter of importance as lionfish are venomous and may put both fishermen and deep divers at risk. In addition, lionfish are voracious predators feeding on shrimp and larval stages of commercially important snapper and grouper. Preliminary research has shown that water column temperature might be controlling the distribution of lionfish within the southeast region and that lionfish density estimates may be approaching abundances similar to many native grouper species.

During both, the summer 2004 and 2005 research missions, populations of lionfish were found to be widespread within Onslow Bay, North Carolina. A total of 22 sites were surveyed in 2004 and 27 sites in 2005 from Cape Fear to Cape Lookout, North Carolina in water depths of 95 to 150 feet deep. Lionfish were present at 86% of the sites in 2004 and 92% of the sites in 2005. In addition, anecdotal and verified reports confirm these findings. Lionfish reports continue to increase along the east coast but more alarmingly are becoming common in the Bahamas as well. This was not expected as the southern extent was thought to be West Palm Beach, Florida. It is unknown whether the Bahamian lionfish represent separate introductions or are a result of dispersal from Florida (Florida straits was thought to be a barrier to southward dispersal). These data suggest that lionfish have become rapidly established within the large southeast marine ecosystem.

Lionfish density estimates from diver transects were obtained from 17 sites in both 2004 and 2005. Preliminary lionfish density estimates suggest that lionfish may be approaching abundances similar to many native grouper species. Between 2004 and 2005 a total of 162 specimens were collected for life history analyses and 57 were collected alive for use in reproductive studies and early life history studies. The lionfish ranged in size from 5 to 45cm in length and weighed from 25 to 1380 grams. Preliminary results from the lionfish reproduction analyses show the sex ratio to be 43%: 57% female to male and that many of the lionfish were reproductively active during the summer off North Carolina but not in the winter. More data are needed from winter, but it appears there is spawning seasonality within the Atlantic lionfish population. Results also suggest that lionfish reproduce early in their life history sometime between 15 and 20 cm total length. More data on lionfish reproduction from the southern end of the range are needed to confirm these results as it is likely that lionfish spawning off Florida (or Bahamas?) are the source of the North Carolina lionfish population

Preliminary lionfish density estimates suggest that lionfish may be approaching abundances similar to many native grouper species. Minimum winter bottom water temperature still remains the single most important factor in controlling the distribution of lionfish within the southeast region.

More information: http://shrimp.ccfhrb.noaa.gov/lionfish/Mission2005/

Contact information
Name: Thomas Potts
pottst@uncw.edu