Latin American Journal of Aquatic Research E-ISSN: 0718-560X [email protected] Pontificia Universidad Católica de Valparaíso Chile Ramírez-Mosqueda, Edith; Pérez-Jiménez, Juan Carlos; Mendoza-Carranza, Manuel Reproductive parameters of the southern stingray Dasyatis americana in southern gulf of Mexico Latin American Journal of Aquatic Research, vol. 40, núm. 2, julio, 2012, pp. 335-344 Pontificia Universidad Católica de Valparaíso Valparaiso, Chile Available in: http://www.redalyc.org/articulo.oa?id=175024254008 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Lat. Am. J. Aquat. Res., 40(2): 335-344, 2012 Reproduction of Dasyatis Americana, Gulf of Mexico 335 DOI: 10.3856/vol40-issue2-fulltext-8 Research Article Reproductive parameters of the southern stingray Dasyatis americana in southern gulf of Mexico Edith Ramírez-Mosqueda1, Juan Carlos Pérez-Jiménez1 & Manuel Mendoza-Carranza2 1Departamento de Aprovechamiento y Manejo de Recursos Acuáticos El Colegio de la Frontera Sur (ECOSUR), Unidad Campeche, Calle 10 #264, Col. Centro, Campeche, México 2Departamento de Aprovechamiento y Manejo de Recursos Acuáticos El Colegio de la Frontera Sur (ECOSUR), Unidad Villahermosa, Carretera Villahermosa-Reforma km 15.5 Ranchería Guineo, sección II, 86280 Villahermosa, México ABSTRACT. The southern stingray Dasyatis americana (Hildebrand & Schroeder, 1928) is the most landed elasmobranch by small-scale fleets in southern gulf of Mexico. However, little is known of its life history parameters in this region. In this study, a total of 900 specimens were collected from February 2006 to December 2008 to determine the reproductive parameters needed for population assessments by means of ecological risk assessments or demographic analysis. Results suggested that females of D. americana reproduce annually, with a gestation of 7-8 months. The reproductive cycle of females is asynchronous, with ovulation and parturition occurring throughout the year. Females and males matured at 764 and 517 mm disc width (DW50) respectively. D. americana has one of the highest fecundity among dasyatids, from 2 to 7 embryos, with a sex ratio of embryos of 1:1. A linear relationship between maternal DW and fecundity was estimated, the larger females contain more embryos. The status of the population of D. americana is a cause of concern in the southern gulf of Mexico due to its high frequency of capture in artisanal fisheries and its apparently low biological productivity. Keywords: Dasyatis americana, disc width at maturity, reproductive cycle, fecundity, gulf of Mexico. Parámetros reproductivos de la raya látigo americana Dasyatis americana en el sur del golfo de México RESUMEN. La raya látigo americana Dasyatis americana (Hildebrand & Schroeder, 1928), conocida como balá en México, es el elasmobranquio más capturado y desembarcado por flotas artesanales en el sur del golfo de México. Sin embargo, se conoce poco de sus parámetros de historia de vida en esta región. En este estudio, fueron analizados 900 ejemplares entre febrero 2006 y diciembre 2008 para determinar los parámetros reproductivos necesarios para evaluaciones poblacionales por medio de análisis demográficos o evaluaciones de riesgo ecológico. Los resultados sugieren que las hembras de D. americana se reproducen anualmente, con una gestación de 7-8 meses aproximadamente. El ciclo reproductivo de las hembras es asincrónico, con la ovulación y alumbramiento ocurriendo a lo largo de todo el año. Las hembras y los machos maduran a los 764 y 517 mm de ancho de disco (AD50), respectivamente. D. americana tiene una de las fecundidades más altas entre los dasyatidos, de 2 a 7 embriones, y con una proporción de sexos de 1:1 en los embriones. Existe relación significativa lineal entre la longitud de las hembras y la fecundidad, las hembras más grandes contenían más embriones. El estado de la población de D. americana es motivo de preocupación en el sur del golfo de México debido a que es muy frecuente en las capturas de pesquerías artesanales y a que su productividad biológica es aparentemente baja. Palabras clave: Dasyatis americana, longitud de madurez, ciclo reproductivo, fecundidad, golfo de México. ___________________ Corresponding author: J.C. Pérez-Jiménez ([email protected]) 336 Latin American Journal of Aquatic Research INTRODUCTION there is a lack of life history parameters throughout most of its range (Grubbs et al., 2006). Mexican The southern stingray Dasyatis americana fisheries for elasmobranchs have been managed since (Hildebrand & Schroeder, 1928) is distributed from 2007 by the Mexican Official Standard NOM-029- New Jersey to Florida in United States, throughout the PESC-2006, Responsible Fisheries of Sharks and gulf of Mexico, Bahamas, and the Greater and Lesser Rays, Specifications for their Use (Poder Ejecutivo Antilles, and bordering the northern coast of South Federal, 2007) and available information from the America to southeastern Brazil (McEachran & de Atlantic coast of Mexico indicates that landings of Carvalho, 2002). It inhabits shallow waters and feeds batoids have been declining since the late 1990’s on bottom-dwelling invertebrates, mainly bivalves and (Poder Ejecutivo Federal, 2006), which indicates that worms (McEachran & de Carvalho, 2002). Although the intrinsic growth potential of the population of D. frequently captured near shore, this species is also americana must be assessed to determine its found in estuaries and rivers (McEachran & vulnerability to fishing pressure. Objectives of the Fechhelm, 1998). D. americana is abundant on sandy present study were to determine the reproductive bottoms of the inner shelf of the gulf of Mexico parameters for D. americana in the southern gulf of (Castro-Aguirre & Espinoza-Pérez, 1996). In the Mexico needed to develop, in the near future, age- western Campeche Bank, in southern gulf of Mexico, structured or stage-based demographic models. D. americana is the most frequently landed among elasmobranch species, with mean landings of 1.400 MATERIALS AND METHODS ton per year in the state of Campeche according to the statistics from the regional office of SAGARPA A total of 900 specimens were examined from (Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación, 2010). February 2006 to December 2008. Rays were obtained from commercial catches of the small-scale fleet from This species reaches a maximum disc width of San Pedro, Tabasco, in the southern gulf of Mexico 1520 mm (Bigelow & Schroeder, 1953). Females and (Fig. 1). Bottom-set longlines with 60 mm shank- males mature at 750-800 and 510 mm DW, length tune circle hooks were the primary method of respectively, young are 170 to 180 mm DW at birth capture. The catch depth ranged from 10 to 40 m. (Bigelow & Schroeder, 1953) and fecundity range from 3 to 5 (McEachran & de Carvalho, 2002). D. Disc width (DW) was measured between the tips americana, as the other dasyatid rays, display of the widest portion of the pectoral fins (McEachran aplacental viviparity with trophonemata (Hamlett et & de Carvalho, 2002). All rays were measured and al., 1996). examined to quantify reproductive parameters. Reproductive parameters estimated for D. ame- Maturity was assessed macroscopically for both sexes. ricana in captivity, showed a biannual reproductive Maturity in males was assessed by the extent of cycle, a gestation period of 4.4-7.5 months, a clasper calcification (Clark & Von Schmidt, 1965) and fecundity of 2-10 with a linear relationship with testes development (Snelson et al., 1988). Claspers maternal disc width, size at birth 200-340 mm disc were measured from the point of insertion at the width, and 1:1 sex ratio for neonates (Henningsen, cloaca to the tip of claspers. Males were assigned to 2000). However, an annual reproductive cycle has one of two stages as follows: 1) immature, testes and been observed on wild specimens from Florida and claspers undeveloped; 2) mature, claspers fully Virginia waters (Grubbs et al., 2006). developed, exceeding the posterior edge of the pelvic fins, presented hardened internal structure and, could The determination of reproductive parameters are be rotated toward the anterior part without bending needed for assessment of elasmobranch populations by means of demographic analysis or ecological risk (Clark & Von Schmidt, 1965), and had enlarged testes assessments due to the lack of time series of catch and with prominent lobes (Snelson et al., 1988). fishing effort by species in Mexican official catch Maturity in females was determined by the onset of statistics. For example, Smith et al. (2008) developed first ovulation (Walker, 2005). Follicle diameter of the age-structured demographic models for Dasyatis largest cohort in the ovary and the width of the left dipterura from the Mexican Pacific coast, concluding uterus were measured. In uteri, the trophonemata that this species has low intrinsic growth potential and development, presence of uterine milk, uterine eggs limited resilience to fishing pressure. and embryos were recorded. Uteri were examined to D. americana is classed as Data Deficient by the determine if embryos or uterine eggs were present. International Union for Conservation of Nature, When present, the sex and DW of embryos was because the status of their populations is unknown and recorded.