169 
National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
established in 1881 
Spencer F. Baird 
First U S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Age and growth parameters of the Panamic 
stingray (Urotrygon aspidura) 
Katherine Torres-Palacios (contact author) 1,3 
Paola A. Mejia-Falla 1,2 
Andres F. Navia 1 
Victor H. Cruz-Escalona 3 
Roberto Fllfx-Uraga 3 
Casimiro Quinonez-Velazquez 3 
Email address for contact author: ktorres@squalus.org 
1 Fundacion Colombiana para la Investigation y Conservation de Tiburones y Rayas 
SQUALUS 
Caile 10A #72-35 
Apartamento 310E 
760033 Cali, Valle del Cauca, Colombia 
Abstract— The aim of this study 
was to estimate the age and growth 
parameters of the Panamic stingray 
(Urotrygon aspidura ) of the Pacific 
coast of Colombia. Vertebral centra 
were removed from 309 individuals 
and used for estimation of age. The 
results of edge type and marginal 
increment analysis indicate an annual 
formation of band pairs. The maximum 
ages estimated were 7.5 and 5.5 years 
for female and male Panamic sting¬ 
rays, respectively. Individual growth 
was described through a multi-model 
approach and inference, by using von 
Bertalanffy, Gompertz, and logistic 
models with 2 and 3 parameters each 
and a two-phase growth model with 4 
and 5 parameters. A two-phase growth 
function of 5 parameters with adjusted 
age provided the best description of 
growth for females (asymptotic disc 
width [DWJ-24.71 cm, growth coef¬ 
ficient [&]=0.47 cm/year, disc width at 
birth [DW 0 ]=8.18 cm, age at transition 
between 2 phases [t h or inflection point 
of the curve] =2.32 years, and maximum 
difference in disc width at age between 
von Bertalanffy and two-phase models 
]/i]=0.36) and males (DV1G--15.96 cm, 
&=1.63 cm/year, DW 0 = 8.07 cm, t h = 
2.22 years, h= 0.54). The growth curves 
were dissimilar between sexes mainly 
after the inflection point, and differ¬ 
ences were found for all parameters, 
except for t h . The Panamic stingray is 
a fast-growing and short-lived elasmo- 
branch, similar to other species of the 
Urotrygonidae. 
Manuscript submitted 24 October 2018. 
Manuscript accepted 16 July 2019. 
Fish. Bull. 117:169-179 (2019). 
Online publication date: 30 July 2019. 
doi: 10.7755/FB. 117.3.4 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
2 Wildlife Conservation Society Colombia 
Avenida 5N #22N-11 
760046 Cali, Valle del Cauca, Colombia 
3 Centro interdisciplinario de Ciencias Marinas 
Institute Politecnico Nacional 
Avenida Instituto Politecnico Nacional s/n 
Colonia Playa Palo de Santa Rita 
Apartado Postal 592 
23096 La Paz, Baja California Sur, Mexico 
Understanding the growth, age, mat¬ 
uration processes, and longevity of 
elasmobranch species is necessary to 
evaluate population status and to pre¬ 
dict variations over time (Cailliet and 
Goldman, 2004), as well as to develop 
management and conservation initia¬ 
tives (Harry et ah, 2010; Smart et ah, 
2013). Rajiformes are the batoid group 
for which the greatest number of stud¬ 
ies on age and growth have been car¬ 
ried out (Shark-References, vers. 2015, 
bibliography database available from 
website), mainly because of their size 
and commercial importance. Con¬ 
versely, small species of no commercial 
importance, such as those belonging 
to the Urolophidae and Urotrygonidae 
(Order Myliobatiformes), have received 
less attention, despite being abundant 
bycatch in shrimp trawl fisheries (Rico- 
Mejfa and Rueda, 2007; Santander- 
Neto, 2015; Clarke et ah, 2016). 
Age and growth studies for the Uro¬ 
trygonidae, both in the American 
Pacific and Atlantic Oceans, have iden¬ 
tified that species of the genus Uroba- 
tis (Babel, 1967; Hale and Lowe, 2008; 
Morales-Azpeitia et ah, 2013; Smith 
et ah, 2013; Spieler et ah, 2013) as well 
as those of the genus Urotrygon (Mejia- 
Falla et ah, 2014; Guzman-Castellanos, 
2015; Santander-Neto, 2015) have high 
growth rates, low maximum ages, and 
early maturation, compared with other 
batoid species (Frisk, 2010) and with 
elasmobranchs in general (Cortes, 2000). 
The Panamic stingray inhabits the 
Eastern Tropical Pacific (Robertson 
and Allen, 2015) and is abundant as 
bycatch in the shrimp trawl fishery 
of that region (Amezcua et ah, 2006; 
Navia et ah, 2009; Navarro-Gonzalez 
et ah, 2012). Despite its high incidence 
in this fishery, this species has been 
little studied with work done on only 
