Explorations |Natural Sciences and Engineering Age And Growth Of The Invasive Lionfish: North Carolina, USA, vs Bonaire, Dutch Caribbean Samantha Farquhar University of North Carolina Wilmington Faculty Mentor: Thomas Lankford University of North Carolina Wilmington ABSTRACT Lionfsh are an invasive species that are now well established throughout the Atlantic. Originally from the Indo-Pacifc, they have decimated local fshes’ populations due to their rapid repro- duction, broad environmental tolerance, voracious appetite, and lack of predators. Through the examination of otoliths paired with morphometric data, this study investigates the age and growth of lionfsh (sp. P. volitans) from two locations: North Carolina, USA and Bonaire, Dutch Caribbean. Otoliths were extracted from lionfsh samples, embedded in resin, and then sec- tioned so that age could be determined with microscopic analysis. These age estimates along with the corresponding total lengths were used to calculate growth rates via the von Bertalanffy growth equation. Results returned a K and L-infnity value of 0.32 cm and 42.5 cm for lionfsh from NC and 0.39 cm and 38.7 cm for Bonaire, respectively. These fndings suggest that lionfsh from NC have slower growth but grow older and larger than that of lionfsh from Bonaire. This likely attributes to location as well as convenience and strength of removal efforts. In Bonaire, lionfsh are hunted often and are easily accessible to the public, whereas in North Carolina, lionfsh are found miles off the coast and their harvesting is not as popular. ionfsh are an invasive species deriv- (Schofeld 2009). This study focuses on spe- Ling from the Indo-Pacifc that have now cies P. volitans. come to thrive in the Atlantic and Caribbean. The earliest sighting of lionfsh in the Invasive lionfsh can be classifed into two Atlantic dates to 1985 off the southeastern species, the fre devil fsh (P. miles) and red coast of Florida and thought to be caused lionfsh, (P. volitans). Both species look and by negligent aquarists. Through mitochon- behave very similar; they both appear to have dria DNA analysis, this was shown to be red and white zebra-like stripes, long pecto- likely source of the invasive (Freshwater et ral fns, venomous spines, and a sedentary, al. 2009). In 2000, multiple individuals were fearless demeanor (Schultz 1986). However, sighted off North Carolina and the surround- meristic counts differ between the species. P. ing states; nine years later, in 2009, lionfsh miles generally has 10 dorsal-fn rays and 6 were seen in Bonaire (de León et al. 2013). anal-fn rays while P. volitans usually has 11 Presently, lionfsh have been found as far dorsal-fn rays and 7 anal-fn rays (Schultz south as Brazil and as far north as New York 1986). Also, Species P. volitans has a wider (Morris and Whitfeld 2009, Freshwater et geographic invasive range than P. miles al. 2009, Green et al. 2012, Ferreira et al. 112 Samantha Farquhar 2015). Lionfsh are expected to continue in- infuences for two very different locations: vading the remainder of the Caribbean and to North Carolina, USA and Bonaire, Dutch continue southward along the coast of South Caribbean. America until the water temperatures fall be- low their thermal tolerance limit (Morris and METHODS Whitfeld 2009). Lionfsh are classifed as generalist car- Lionfsh samples were obtained from both nivores that feed on a wide variety of fshes locations during the summer of 2015 (June and crustaceans (Morris and Akins 2009). – August) (Figure 1). In North Carolina, 21 Lionfsh consume prey at high rates, largely lionfsh were purchased from local fsherman during crepuscular periods (Green et al. after their returns from the Onslow Bay area. 2012). Their hunting strategy is unique In Bonaire, 17 lionfsh were speared and do- among predatory fshes within the Caribbean. nated by locals. Bonaire samples all were Lionfsh hover motionless over prey with from the west coast of the island. However, their large pectoral fns extended and are able due to human or experimental error, only 13 to approach their prey closely before making otoliths from each location were able to be a rapid strike. They also can extrude water completely evaluated. jets to orient the prey towards the mouth be- For all samples collected, the species was fore striking (Albins and Lyons 2012). Their verifed, total length (TL) recorded, and the relentless predation wreaks havoc on com- sagittal otoliths were extracted. Otoliths are munities. For example, a 79% reduction in small bones that are found within fshes’ cra- fsh recruitment on experimental patch reefs niums that help facilitate balance, orienta- in the Bahamas was observed during a fve- tion, and sound (Secor et al. 1991). As these week observation period in the presence of bones grow, they form annual rings similar a single small lionfsh (Albins and Hixon to like rings of a tree. These annuli can be 2008). Another study reported lionfsh prey counted to give age estimates and used in biomass reduced by an average of 65% over further calculations to produce growth curves a two-year-period (Green et al. 2012). This (Secor et al. 1991). The otoliths were embed- mass predation is cause for concern as the ded in resin, mounted, and sectioned with an over-consumption of herbivore fshes can Isomet™ Low Speed Saw as following pro- shift ecosystems to algae dominated coral as tocol from the Manual for Otolith Removal shown by Lesser and Slattery (2011). These and Preparation for Microstructural shifts that can effect both habitat and econ- Examination (Secor et al. 1991). Sections omy as seen during the mass extinction of the were then analyzed for annuli under a com- sea urchin, Diadema antillarum in the 1980’s pound microscope to determine age. Further (Mumby et al. 2006). analysis for growth was conducted follow- Lionfsh are extremely tolerant and adap- ing protocol set forth by the FAO’s (Food tive. They have been reported from all major and Agriculture Organization of the United marine seafoor and substrate types within Nations) manual, Introduction to Tropical the invaded Atlantic, and they occupy a Fish Stock Assessment (Sparre and Venema range of depths (Morris et al 2009). They 1998). have no known predators and a proven vora- The age estimates from the otolith analy- cious appetite; this paired with their ability to ses along with the corresponding total lengths reproduce every 4 days drives their success were used to calculate a growth rates via the (Morris et al 2009). Through the analysis of von Bertalanffy growth equation (Table 1.): otoliths and recorded total lengths, this study aims to (1) produce von Bertalanffy growth curves and (2) investigate the age structure and growth with regards to environmental where l(t) is length at time, t(0) is the 113 Explorations |Natural Sciences and Engineering Figure 1. Map of study area 114 Samantha Farquhar Table 1. Raw otolith and corresponding age data for samples from North Carolina and Bonaire Table 2. Comparison between parameters of von Bertalanffy growth equation for North Carolina and Bonaire 115 Explorations |Natural Sciences and Engineering theoretical length at age 0, K is the growth the parameter, t(0) was calculated by creat- rate and L∞, termed ‘L infnity’ in fsheries ing a Von Bertalanffy plot. This plots age (t) science, is the asymptotic length at which against: growth is zero(von Bertalanffy 1934). This equation assumes that body length is a func- tion of age. Parameters for this equation were from the linear regression of this plot, t(0) calculated by the Ford-Walford plot. This plot can be simply calculated by: graphs a fsh’s length at year (t+1) against the fsh’s length the previous year (t) producing the equation: RESULTS AND DISCUSSION Results return a K and L-infnity value of From this, the following parameters can 0.32 cm and 42.5 cm for lionfsh from NC be calculated from the linear regression via: and 0.39 cm and 38.7 cm for Bonaire, re- spectively (Table 2 and Figure 2). The age range of lionfsh found in North Carolina was 0.6-6.0 years old with an average age of 2 years old (Figure 3). Bonaire lionfsh showed a range of 0.1-5.0 years old with an average Figure 2. Von Bertalanffy growth curves calculated from lionfsh samples for both North Carolina and Bonaire 116 Samantha Farquhar Figure 3. Age structure of lionfsh samples from Bonaire and North Carolina age of 1 year (Figure 3). 29°C (84°F). These warmer temperatures These results are similar to those found increase metabolic efforts which in turn af- in past studies from the Western Atlantic fects growth (Thresher et al. 2007). The age and Caribbean. One study from the Cayman structure seen in Figure 3 is likely attributed Islands reported lionfsh with a K growth rate to other environmental infuences such as lo- of 0.42 and a L∞ value of 34.9 cm (Edwards cation and accessibility. Bonaire is a small et al. 2014) while another from Onslow Bay, island renowned for its convenience for pris- NC reported lionfsh with a K growth rate tine diving. Local efforts to eliminate lion- of 0.32 and a L∞ value of 45.5 cm (Potts et fsh and help protect and conserve Bonaire’s al. 2010). While the von Bertalanffy growth reefs are strong. Government organizations function (VBGF) is widely accepted, the (STINAPA), educational institutes (CIEE assumptions and limitations should be rec- Research Station Bonaire), local dive shops, ognized (Pardo et al. 2013). The VBGF is and visitors work closely together reporting was not adjusted for seasonality which could and monitoring lionfsh sightings to each produce variations in the growth coeffcient.