126 
Fishery Bulletin 117(3) 
species on native fish species and coral reef communities 
(Dahl and Patterson, 2014; Albins, 2015; Benkwitt, 2015; 
Ingeman and Webster, 2015; Rocha et al., 2015; Acero 
et ah, 2019) and on aspects of landscape-level movements 
among reef systems and invasion control efforts (Frazer 
et ah, 2012; Green et ah, 2014; Tamburello and Cote, 2015). 
Results from a recent study indicate that red lionfish have 
unique morphological functional traits that reduce the 
theoretical ecological space of 5 coral reef mesopredators 
of the Caribbean Sea (Rojas-Velez et ah, 2019). However, 
data are limited for age and growth of lionfish species 
throughout the geographic range that they have invaded. 
Knowledge of weight-length relationships, size and age 
structure, and growth patterns are important for the suc¬ 
cessful assessment and management of species. This infor¬ 
mation can also be used to assess the effects of invasive 
species on native species and the ecosystems they inhabit. 
For example, although data such as weight-length relation¬ 
ships are generally useful for quantifying changes in size or 
age structure that relate to potential overexploitation of a 
species (Berkeley et al., 2004; Dulvy et al., 2004), such data 
also could be used as indicators of success in management 
of invasive species (Pasko and Goldberg, 2014). Addition¬ 
ally, weight-length relationships could be used to exam¬ 
ine changes in population structure during post-culling 
activities or following large-scale disease or environmental 
perturbation (e.g., an algal bloom). Although a number of 
studies have reported basic weight and length data for inva¬ 
sive lionfish (Barbour et al., 2011; Fogg et al., 2013; Dahl 
and Patterson, 2014; Edwards et al., 2014; Sabido-Itza et al., 
2016), few make comparisons between regions or sexes. 
Estimations of age and growth relationships for species 
within invaded geographic ranges are important for describ¬ 
ing spatially explicit variation in life history. Larger and 
older fish tend to affect ecosystems differently than smaller 
and younger individuals because diet and habitat use can 
change with age and size (Curtis et al., 2017; Mizrahi et al., 
2017; Garcia-Rivas et al., 2018). Age and growth patterns 
of lionfish vary geographically. Johnson and Swenarton 
(2016) verified their length-based model outputs with ages 
determined from a subsample of 100 sectioned otoliths from 
fish (age 0-3; maximum size of 342 mm in total length [TL]) 
captured offshore of Jacksonville, Florida. Additional infor¬ 
mation from other studies conducted outside of the COM 
illustrates this variation. Lionfish captured in Onslow 
Bay, North Carolina, had a maximum age of 8 years, with 
more than 90% of these fish (number of samples examined 
[n]=814) <3 years old (Potts et al., 2010; Barbour et al., 2011). 
Two red lionfish collected off the coast of South Carolina, at 
sizes of 352 and 389 mm TL, were determined to be 5 and 6 
years old, respectively (Meister et al., 2005). 
Limited data from regions in the GOM and the Caribbean 
Sea indicate similar variation. Red lionfish collected from 
the Dry Tortugas in the Florida Keys had a maximum age of 
7 years (Dubel 1 ). Rodriguez-Cortes et al. (2015) provided the 
1 Dubel, A. M. 2017. Age structure and growth of lionfish (Pterois 
volitans ): the Dry Tortugas National Park. Internship Rep. 32, 
40 p. Univ. Miami, Miami, FL. [Available from website.] 
first growth and mortality estimates for the southern region 
of the GOM (Mexico), although the modeled lengths of red 
lionfish (n=776; range: 90-389 mm TL) from that study were 
not verified by using otoliths. Edwards et al. (2014), using 
otoliths from 110 male and 128 female lionfish captured off 
Little Cayman, found a maximum age of only 5 years and 
confirmed annual annuli formation for fish from that region 
of the Caribbean Sea. However, no ages determined from 
analysis of wild-caught lionfish are as old as the ages of lion¬ 
fish held in captivity (30-33 years; Potts et al., 2010). 
Lionfish species have invaded different regions of the 
GOM and the Caribbean Sea at different times (Schof¬ 
ield, 2010) and can be found in vastly different ecosystems 
(Barbour et al., 2010; Jud et al., 2011; Claydon et al., 2012; 
Ruttenberg et al., 2012) and different densities (Green and 
Cote, 2009; Darling et al., 2011; Dahl and Patterson, 2014). 
Therefore, we expected that age and growth parameters 
would vary by location, a notion that Villasenor-Derbez and 
Fitzgerald (2019) have since verified. Additionally, rapid 
growth rates generally lead to successful invasion of an area 
by a species; therefore, it is important to estimate growth rates 
(Copp and Fox, 2007). Although age and growth data have 
been reported for portions of the invaded geographic range, 
growth of red lionfish could differ between the southern and 
northern regions of their non-native range (Barbour et al., 
2011). Therefore, we hypothesized that the age structure of 
red lionfish is much younger in the northern GOM than in 
other invaded regions where they have been established for 
a longer period. The goal of this study was to determine if 
differences in weight and length and in age and growth rela¬ 
tionships exist by sex or across the northern GOM. 
Materials and methods 
Initially, we did not identify our specimens to species, 
instead putting them in a complex that comprises both 
Pterois volitans and P. miles because it was unknown at 
the beginning of our study if both species occurred in the 
GOM (Hamner et al., 2007; Brown-Peterson and Hendon, 
2013; Fogg et al., 2013) or if there were hybrids in the 
GOM. Results from subsequent work, including a study 
that used specimens we provided for genetic analysis, 
indicate that the red lionfish is the only species detected 
to date in the northern GOM (Johnson et al., 2016). There¬ 
fore, we identify all specimens that we collected in the 
northern GOM throughout our study as P. volitans. 
From 2012 through 2015, red lionfish were collected 
opportunistically every month (for details about speci¬ 
men collection, see Fogg et al., 2017) across 3 ecological 
regions (or ecoregions) of the northern GOM: southeast 
(from the Florida Keys north to Anclote Keys, Florida), 
northeast (from the Anclote Keys north to Mobile Bay, 
Alabama), and central (west of Mobile Bay to Galveston 
Bay, Texas; 1 fish was collected west of Galveston Bay) 
(Fig. 1). Clearly identified, ecologically relevant ecoregions 
in the GOM and the Caribbean Sea vary and are debated 
because authors use somewhat different environmental 
data and quantitative approaches to delineate ecoregions 
