Fernandez-Carvalho et al.: Age and growth of Alopias superciliosus in the Atlantic Ocean 
475 
Table 2 
Estimated means for growth parameters of bigeye thresher ( Alopias superciliosus) collected from the Atlantic Ocean between 
2007 and 2009, obtained with the regular 3-parameter von 
Bertalanffy growth function (VBGF) 
model, the VBGF model 
with a fixed size 
at birth (Lq), the 3-parameter Gompertz growth function (GGF) model, and the GGF model with a fixed 
L 0 (Lq= 84 cm in 
fork length). For each model, the estimated 
means for parameters, including asymptotic maximum length 
(Lj n f), growth coefficient ( k ), size at birth (Lq), and instantaneous rate of growth (G), are 
given with their respective standard 
errors (SE) and 95% confidence intervals (CIs). The Akaike 
nformation criterion (AIC) and Bayesi 
an information criterion 
(BIC) values are given for a comparison of models within each sex group. 
95% Cl 
Sex 
Model 
AIC 
BIC 
Parameter 
Mean 
SE 
Lower 
Upper 
Sexes combined 
L; n f 
263.50 
7.516 
248.75 
278.28 
VBGF 
3827.1 
3843.9 
k 
0.07 
0.006 
0.06 
0.08 
Lo 
108.80 
1.623 
105.63 
112.01 
VBGF fixed L 0 
3984.0 
3996.6 
^inf 
k 
224.70 
0.14 
2.513 
0.005 
219.72 
0.13 
229.59 
0.15 
G 
0.80 
0.016 
0.77 
0.83 
GGF 
3837.1 
3854.0 
k 
0.11 
0.007 
0.09 
0.12 
Lo 
110.90 
1.494 
107.91 
113.79 
GGF fixed L 0 
4042.2 
4054.8 
G 
k 
0.94 
0.22 
0.009 
0.006 
0.92 
0.20 
0.96 
0.23 
Males 
-^inf 
245.60 
7.535 
230.73 
260.42 
VBGF 
1831.0 
1845 
K 
0.09 
0.009 
0.07 
0.10 
Lq 
108.50 
2.306 
103.91 
113.00 
VBGF Fixed L 0 
1908.8 
1919.2 
^inf 
K 
218.10 
0.16 
3.077 
0.008 
211.99 
0.14 
224.11 
0.18 
G 
0.75 
0.020 
0.71 
0.79 
GGF 
1835.4 
1849.4 
K 
0.12 
0.010 
0.10 
0.14 
Lq 
110.30 
2.143 
106.10 
114.55 
GGF fixed L 0 
1936.2 
1946.6 
G 
K 
0.92 
0.23 
0.011 
0.009 
0.90 
0.21 
0.94 
0.25 
Females 
Linf 
284.20 
14.430 
255.76 
312.60 
VBGF 
1993.3 
2007.5 
k 
0.06 
0.008 
0.04 
0.08 
Lq 
109.00 
2.249 
104.61 
113.47 
VBGF fixed L 0 
2073.7 
2084.3 
^inf 
k 
231.90 
0.13 
4.037 
0.007 
223.99 
0.12 
239.89 
0.15 
G 
0.86 
0.027 
0.80 
0.91 
GGF 
1998.5 
2012.8 
k 
0.10 
0.009 
0.08 
0.11 
L 0 
111.20 
47.000 
107.20 
115.27 
GGF fixed L 0 
2105.9 
2116.5 
G 
k 
0.96 
0.20 
0.014 
0.008 
0.94 
0.19 
0.99 
0.22 
age counts by using a hexagon plot, as described by 
Evans and Hoenig (1998). The values obtained in this 
study, together with the results of the age-bias and 
symmetry plots, indicate that our age estimates are 
consistent and adequate for this species. 
It was not possible to objectively determine mar- 
ginal growth increments because of the morphological 
structure of the vertebrae of bigeye thresher; these ver- 
tebrae were very difficult to read as a result of the nar- 
row and faint bands at their edges. Few studies on the 
age and growth of alopiid sharks exist, and of these the 
majority of studies have focused on the Pacific Ocean 
(bigeye thresher: Liu et al., 1998; common thresher 
shark (A. vulpinus ): Cailliet and Bedford, 1983; Smith 
et ah, 2008; and pelagic thresher (A. pelagicus): Liu et 
al., 1999), only 2 studies have been conducted within 
the North Atlantic Ocean (bigeye thresher: Fernandez- 
Carvalho et ah, 2011; common thresher shark: Gervelis 
and Natanson, 2013), and 1 study in the South Atlantic 
Ocean (bigeye thresher: Mancini, 2005). 
