Lionfish stable isotope values and stomach contents from the Florida Keys, 2018-2019, 74 samples

Seventy-four lionfish (Pterois volitans and Pterois miles) specimens were collected from September 2018 to June 2019 near Marathon Key, Florida. The sampling sites were all within 30 km of each other. Fish were collected from patch reefs of predominantly hard corals with some octocorals and sponges. The depths of collection sites ranged from 13.7 m to 57.9 m and were separated into “shallow <30 m” (n=35) and “deep >30 m” (n=39) categories based on the recreational diving depth limit and the distribution of sample depths. Forty-five of these fish were caught using a pole-spear, both in deep and shallow waters, by recreational divers. The remaining 29 fish were captured in passive traps deployed from 34-58 m depth by Florida Fish and Wildlife Conservation Commission. Due to the opportunistic collection of samples, there were no shallow lionfish caught in traps. To account for the temporal variation, a “season” factor was used to split between 21 samples collected during September 2018 using pole spears (“fall”), and 53 samples collected between April and June 2019, 29 of which were caught in traps and 24 with pole spears (“spring”) to capture any seasonal variability. Specimens were frozen after collection and during transportation or shipment to Baton Rouge, Louisiana. Four “spring deep” samples were not used for isotope analysis because of poor tissue condition. A 1 cm^3 piece of muscle tissue was removed posterior to the dorsal fin of 70 lionfish samples (Layman and Allgeier 2012). Prior to dissection, fish standard length (SL) and mass were recorded. Samples were freeze-dried and ground until homogenous. For each muscle sample, 0.5 mg was placed into individual tin cups and flash-combusted using a Thermo-Finnigan element analyzer. Samples were analyzed for δ 13 C and δ 15 N values using the Thermo-Fisher Delta Plus XL continuous flow stable isotope mass spectrometer at the Stable Isotope Ecology Laboratory at Louisiana State University. Raw δ values were normalized using a two-point system using glutamic acid reference material (USGA-40 and USGS-41) and the sample precision was <0.1. Fish stomachs were removed and the contents examined. Prey objects were identified to the lowest taxonomic group.