National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
@& established in 1881 << 
Spencer F. Baird C \ 
First U.S. Commissioner aN 
of Fisheries and founder His 
of Fishery Bulletin 
Abstract—The aim of this study was to 
use a Bayesian approach to estimate age 
and growth parameters for the golden 
cownose ray (Rhinoptera steindachneri) 
in the southern Gulf of California in 
Mexico. Age estimates were obtained 
through analysis of vertebrae of 249 
individuals. The von Bertalanffy growth 
function (VBGF) and Gompertz growth 
model (GM) were fit to length-at-age 
data by using a Markov chain Monte 
Carlo algorithm for parameter estima- 
tion. Prior distributions of parameters 
were included for an informative prior 
for disc width at birth (DW,) and unin- 
formative priors for the theoretical 
maximum disc width (DW.,) and growth 
coefficients (k and g, for the VBGF and 
GM, respectively). Our results indicate 
that the golden cownose ray lives up to 
13 years. The GM for combined sexes 
was selected as the best model by using 
the Watanabe—Akaike information cri- 
terion for model selection suitable for 
Bayesian estimation. The mean values 
of the GM parameters were as follows: 
DW.=101.10 cm (95% credible inter- 
val [CI]: 94.19-110.43), g=0.15 year! 
(CI: 0.12-0.18), and DW,=40.00 cm 
(CI: 39.29-40.71). This study of the 
golden cownose ray contributes to the 
information available to develop better 
management and conservation strate- 
gies for this species. 
Manuscript submitted 30 June 2020. 
Manuscript accepted 3 March 2021. 
Fish. Bull. 119:10—20 (2021). 
Online publication date: 22 March 2021. 
doi: 10.7755/FB.119.1.3 
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. 
Bayesian estimation of the age and growth of the 
golden cownose ray (Rhinoptera steindachneri) 
in the southern Gulf of California in Mexico 
Luis D. Carrillo-Colin' 
J. Fernando Marquez-Farias (contact author)” 
Raul E. Lara-Mendoza? 
Oscar G. Zamora-Garcia* 
Email address for contact author: fmarquez@uas.edu.mx 
" Posgrado en Ciencias del Mar y Limnologia 
Universidad Nacional Autonoma 
de Mexico 
Avenida Ciudad Universitaria 3000 
04510 Coyoacan, Mexico City, 
Mexico 
? Facultad de Ciencias del Mar 
Universidad Autonoma de Sinaloa 
Paseo Claussen s/n 
82000 Mazatlan, Sinaloa, Mexico 
The golden cownose ray (Rhinoptera 
steindachneri) ranges from the Gulf of 
California (GOC) to Peru, including the 
Galapagos Islands. Abundant in the 
GOC in summer, this species inhabits 
coastal waters and migrates season- 
ally (McEachran and Notarbartolo-di- 
Sciara, 1995). Bizzarro et al. (2007) 
investigated the biology of the golden 
cownose ray in the GOC and reported 
a maximum length of 104 cm disc width 
(DW) and a median length at matu- 
rity of around 70 cm DW. This species 
produces a single embryo at a size of 
38-45 cm DW after 12 months of ges- 
tation. Low fecundity, typical of chon- 
drichthyan species, is recognized as a 
limiting factor for the sustainability 
of the fisheries that target them and 
leads to the rapid overexploitation of 
populations. 
The GOC supports the largest arti- 
sanal and multi-specific ray fishery in 
Mexico, and the golden cownose ray is 
among the most commonly captured 
3 Direccién General Adjunta de Investigacién 
Pesquera en el Atlantico 
Instituto Nacional de Pesca y Acuacultura 
Secretaria de Agricultura y Desarrollo Rural 
Avenida Mexico 190 
Colonia del Carmen 
04100 Coyoacan, Mexico City, Mexico 
“ Servicios Integrales de Recursos Biolégicos, 
Acuaticos y Ambientales 
Calle Genaro Estrada 406 Centro 
82000 Mazatlan, Sinaloa, Mexico 
species (Bizzarro et al., 2007). Its dor- 
soventrally flattened and broad body 
makes it susceptible to being caught in 
gill-net fisheries and as bycatch by the 
trawlers licensed to catch shrimp and 
operate in the GOC (Marquez-Farias, 
2002). Despite the importance of the 
golden cownose ray in the artisanal ray 
fishery of the GOC, detailed informa- 
tion on the life history of this species 
and age estimates are scarce. Aging is 
necessary to determine age-specific sur- 
vival and reproduction rates, which are 
useful for assessing species productivity 
(Cortés, 1998). However, determining 
age in chondrichthyans is challenging 
because of the logistical problems of col- 
lecting samples that result from their 
seasonal migrations and because of the 
difficulty of identifying growth bands in 
hard parts (Cailliet, 2015). Growth is a 
fundamental component of life history, 
and the ability to model it is impera- 
tive for practical fishery assessments 
(Smart et al., 2016). 
