Feminización de juveniles del Robalo Blanco Centropomus Undecimalis (Bloch 1792) usando 17β-Estradiol

Abstract

El robalo blanco Centropomus undecimalis es un pez protándrico hermafrodita con un alto valor comercial y potencial de cultivo en México y Estados Unidos de América, y en Centroamérica y el Caribe es sustento importante de su pesca artesanal. Diversos estudios indican que las hembras aparentemente presentan un mayor crecimiento que los machos. El objetivo del presente estudio consistió en evaluar el efecto de la suplementación del esteroide 17-β estradiol (E2) en el alimento sobre la proporción de sexos de esta especie bajo condiciones de laboratorio. Para ello se realizó un estudio donde se evaluaron seis tratamientos (tiempos de exposición) con 17-β estradiol (7, 14, 21, 28, 35 y 42 días) usando alimento impregnado con 50 mg kg-1 de 17-β estradiol y una dieta control sin esteroide.Después de los días de exposición, los peces fueron mantenidos con dieta sin 17-β estradiol hasta completar 204 días de crianza, determinándose la proporción de sexos, crecimiento y supervivencia. Al final del período de crianza, los peces alimentados con dieta enriquecida con 17-β estradiol por 21 y hasta 42 días muestran la mayor proporción de hembras (93%), mientras que el grupo control presentó el 100% de machos. El mayor crecimiento en longitud y peso se obtuvo en los peces alimentados por 21 días con el E2 (193.11 ± 1.83 mm y 28.56 ± 0.63 g) comparado con el resto. La supervivencia no mostró diferencias significativas entre los tratamientos (92% a 98%). Se concluye que es posible obtener altos porcentajes de feminización utilizando 17-β estradiol al alimentar a los peces por al menos 21 días. Abstract Common snook Centropomus undecimalis is a protandric fish with a high commercial importance and aquacultural potential in Mexico and the United States. Several studies indicate that females have higher growth capacity than males. For this reason, the objective of this research was to evaluate the effect of a 17β-estradiol (E2) diet supplementation on sex proportion for this species. In this sense, an experimental study was conducted where fish were fed for different time periods (7, 14, 21, 28, 35, and 42 days) with food impregnated with 50 mg of E2/Kg, and one control diet without the presence of the steroid. After feeding times, fish were raised for additional 204 days with the control diet to evaluate sex proportion, growth and survival. Our results showed that fish fed with E2 for 21 days or more had the highest female sex proportion (93-100%), while the control group showed the highest male proportion (100%). The highest growth (weight and total length) was detected in fish fed with E2 for 21 days (193.11 ± 1.83 mm and 28.56 ± 0.63 g) compared with the rest of the treatments. Survival did not show statistical differences between treatments (92-98%). We conclude that high percentage of C. undecimalis females can be obtained when fish are fed for 21 days or more with artificial food supplemented with E2.

Distribution and Habitat Associations of Juvenile Common Snook in the Lower Rio Grande, Texas

“…Differences in size and development within each age-group were presumably due to the protracted spawning period that is typi-cal for Common Snook (April through September; Taylor et al 1998). Our observations on the development of juvenile testes are consistent with the results of a laboratory study describing the early gonadal development in Common Snook (Vidal-López et al 2012). However, it is highly unlikely that any age-2 males examined reached breeding condition during their first potential spawning season as age-1 fish in the preceding year (springsummer 2005), given the very early developmental stage of age-1 testes.…”

Functional feminization of the Mexican snook (Centropomus poeyi) using 17β estradiol in the diet

“…These studies have examined the use of different steroids and dosages, lengths of steroid treatment and gonad development. With centropomids, specifically C. undecimalis and C. parallelus, positive results were obtained when the steroid was supplied using food or implants, obtaining high percentages of feminization in both species (Vidal-López et al, 2012;Passini et al, 2016).…”

“…Green et al (1997) attempted to differentiate induction of sex change, in undifferentiated and differentiated fish, by arguing that the term "sex inversion" is defined as the process where the undifferentiated gonad is directed to a particular sex, and "sex reversal" as the induction of a differentiated gonad to become that of the opposite sex. In the case of hermaphroditic species, both terms stand, since sex change can be induced during both stages of gonadal development, supported by the successful sex inversion of juvenile sea bream, Sparus aurata (Condeça & Canario, 1999); common snook, C. undecimalis (Vidal-López et al, 2012; and fat snook, C. parallelus . While sex reversal has been documented for adult blue-spotted grouper, Epinephelus fario (Kuo et al, 1988), black porgy, Acanthopagrus schlegeli (Chang, et al, 1994(Chang, et al, , 1995, black sea bass, Centropristis striata L. (Benton & Berlinsky, 2006), three-spot wrasse, Halichoeres trimaculatus (Nozu, et al, 2009), and adult fat snook (Passini et al, 2016).…”

Induction of sex inversion in common snook (Centropomus undecimalis) males, using 17-β oestradiol implants

“…In a recent study of feminization with common snook juveniles, the administration of 50 mg kg −1 of E2 in the diet for 21 days resulted in up to 93% of females (Vidal‐López et al . ). These results, together with the present study, demonstrate that E2 can induce both change in undifferentiated fish (feminization) and sex reversal in adult common snook.…”

“…; Du, Lee, Tacon, Lee, Yen, Tanaka, Dufour & Chang ; Wu, Tomy, Lee, Lee, Yueh, Lin, Lau & Chang ). There has also has been a study on feminization of the common snook by the E2 hormone (Vidal‐López, Álvarez‐González, Contreras‐Sánchez, Patiño, Hernández‐Franyutti, Hernández‐Vidal & Martínez‐García ), but there are no records in the literature of studies using implants with 17‐β oestradiol in adult common snook.…”