Field experiment on artificial patch reefs to test for presence of density dependence in invasive red lionfish recruitment, immigration, loss, and growth (in mass and length).  Juvenile lionfish (40 - 71 mm total length [TL]) were collected from surrounding reefs by SCUBA divers using handnets and held in 190-l flow-through aquaria prior to release onto the experimental matrix. All lionfish were tagged subcutaneously using colored elastomer (Northwest Marine Technology Inc., Shaw Island, Washington, USA) on the caudal peduncle and/or slightly anterior to the caudal peduncle just under the dorsal fins.  All fish were held for at least 12 hours after tagging to allow for recovery from any tagging effects and measured (TL to nearest 1 mm) and weighed (wet weight [WW] to nearest 1 mg) just before being released onto the experimental reefs.  Lionfish were transplanted to 10 artificial patch reefs (each measuring 1 cubic meter) so that 4 reefs had 0 lionfish on them (controls) and 6 each had a unique density of lionfish (2, 4, 6, 8, 10, or 12 lionfish).  To account for changes in lionfish density throughout the course of the experiment, we also calculated the weighted average weekly lionfish density for each reef (1, 2, 4, 7, 10, and 12 lionfish/m^2 rounded to the nearest fish).

A pair of trained observers using SCUBA recorded the number and identity of tagged lionfish present on each reef weekly.  If a lionfish was not seen on a reef, we searched the surrounding sand and seagrass for approximately 10 minutes. If the lionfish was still not found, it was marked as absent for that week. If never found again, it was marked as lost from the last day it was seen.  We recorded the number of new lionfish recruits present on each reef weekly.  Any new lionfish were immediately removed to preserve the treatment densities.  Every two weeks, we recaptured all tagged lionfish on scuba using handnets, re-measured their TL in situ, and immediately released them back to their original locations on the reef. At the conclusion of the experiment (after 8-weeks), lionfish were re-captured and re-weighed.

All data were entered by one person, and then subsequently checked by another person to ensure accuracy.