Age and Growth of the Round Stingray Urotrygon rogersi, a Particularly Fast-Growing and Short-Lived Elasmobranch Paola A. Mejı´a-Falla 1,2 *, Enric Corte ´s 3 , Andre ´s F. Navia 1 , Fernando A. Zapata 2 1 Fundacio ´ n Colombiana para la Investigacio ´ n y Conservacio ´ n de Tiburones y Rayas, SQUALUS, Carrera 60A No 11-39, Cali, Colombia, 2 Grupo de Investigacio ´n en Ecologı ´a de Arrecifes Coralinos, Departamento de Biologı ´a, Universidad del Valle. A.A. 25360, Cali, Colombia, 3 NOAA/National Marine Fisheries Service, Panama City, Florida, United States of America Abstract We examined the age and growth of Urotrygon rogersi on the Colombian coast of the Eastern Tropical Pacific Ocean by directly estimating age using vertebral centra. We verified annual deposition of growth increments with marginal increment analysis. Eight growth curves were fitted to four data sets defined on the basis of the reproductive cycle (unadjusted or adjusted for age at first band) and size variables (disc width or total length). Model performance was evaluated using Akaike’s Information Criterion (AIC), AIC weights and multi-model inference criteria. A two-phase growth function with adjusted age provided the best description of growth for females (based on five parameters, DW ‘ = 20.1 cm, k = 0.22 yr –1 ) and males (based on four and five parameters, DW ‘ = 15.5 cm, k = 0.65 yr –1 ). Median maturity of female and male U. rogersi is reached very fast (mean 6 SE = 1.0 6 0.1 year). This is the first age and growth study for a species of the genus Urotrygon and results indicate that U. rogersi attains a smaller maximum size and has a shorter lifespan and lower median age at maturity than species of closely related genera. These life history traits are in contrast with those typically reported for other elasmobranchs. Citation: Mejı ´a-Falla PA, Corte ´s E, Navia AF, Zapata FA (2014) Age and Growth of the Round Stingray Urotrygon rogersi, a Particularly Fast-Growing and Short- Lived Elasmobranch. PLoS ONE 9(4): e96077. doi:10.1371/journal.pone.0096077 Editor: A. Peter Klimley, University of California Davis, United States of America Received January 7, 2014; Accepted April 2, 2014; Published April 28, 2014 This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Funding: This study was partially supported by the PADI Foundation (www.padifoundation.org), the Initiative of Endangered Species (IEA-Scolarships, http:// www.omacha.org/2012-04-12-18-55-26/iniciativa-de-especies-amenazadas) and the Colciencias-Universidad del Valle-SQUALUS project (Code: 1106-452-21080, Contract: RC-258-2008). P.A.M. was funded by a scholarship from Colciencias (www.colciencias.gov.co) for PhD studies. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: pmejia@squalus.org Introduction Knowledge of age and growth characteristics allows construc- tion of age-based population models and, together with the consideration of other life history aspects and removal rates by fisheries, can eventually lead to an assessment of the population status of a given species [1]. While target species have often been intensely studied, bycatch species are often ignored. These commercially unimportant species, such as the stingrays in the Family Urotrygonidae, are also impacted by fisheries and information on their life history is needed as input to formulate fisheries management decisions. The round stingray Urotrygon rogersi (Jordan and Starks 1895) is an endemic batoid of the Eastern Tropical Pacific Ocean that occurs on soft bottoms in coastal and shallow zones at depths of 2 to 30 m [2]. It is the most abundant elasmobranch species in the bycatch of artisanal and industrial prawn trawl fisheries on the Colombian Pacific coast and does not have any commercial value [3]. This species is a specialist that feeds mainly on crustaceans and polychaetes, showing a strong diet overlap between sexes and size classes [4]. This aplacental viviparous species attains a maximum size of 20 cm disc width (DW), its median size at maturity is 11.5– 11.8 cm DW in males and 11.8–12.3 cm DW in females, size at birth is 7.5–8.2 cm DW and 11.5–14.7 cm total length, gestation lasts about 5–6 months, and the reproductive cycle is triannual and aseasonal [5]. Seasonally reproducing species usually have relatively well- defined birth dates [6] and therefore the age of individuals can be determined with reasonable accuracy [7]. In contrast, non- seasonally reproducing species can have several reproductive peaks or reproduce throughout the year [6], and consequently the age at which the first growth band is formed in a vertebra is unknown. Therefore, age determination based on vertebral growth bands in these species requires that the data be adjusted, specifically by averaging the time between births and the formation of the first growth band [7]. Important considerations when fitting growth curves to observed size-at-age data include the metric of body size and the type of growth curve used. Most studies use total length, yet other metrics may be more relevant for some shark and batoid species [8–10]. Although the von Bertalanffy growth curve has been most extensively used to describe growth in fishes, use of more than one growth function to adequately characterize the growth of a given species has been recommended [11] and used in different elasmobranch species [10,12–15]. However, few elasmobranch studies [13,15,16] have used multi-model inference, as proposed by Katsanevakis [17], to determine a model-averaged set of PLOS ONE | www.plosone.org 1 April 2014 | Volume 9 | Issue 4 | e96077