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

Abstract

The Mexican snook, Centropomus poeyi, supports an important fishery in southeastern Mexico. Due to its protandrous hermaphroditism, females may be especially sensitive to overfishing because they tend to be larger and selective removal has the potential to negatively affect natural populations, thus making urgent the need to contribute on management strategies for the species. The objective of this study was to produce batches of reproductive females at an early age and a small size by using 17β-estradiol (E2) in the diet. In two separate experiments, we fed fish 0, 10, 20, 30, 40, 50, or 60 mg of 17β-estradiol per kg of food for 60 days during gonadal differentiation. Fish fed with 50 and 60 mg of E2 per kg of food resulted in 100% feminization, while the control group (0 mg of E2) was 100% male. Three years after feminization, sex-reversed fish remained female, producing oocytes and were capable of spawning, while fish in the control group were ripe males with running milt. E2-treated groups were significantly larger (weight and length) than the control groups for up to six months after treatment, but the difference was undetectable at 300 days post-treatment. Survival was high in all treatments (100%). We obtained high percentages of functional females using dosages of 50 and 60 mg kg -1 of E2 for 60 days, with 80% of the induced fish spawning and producing fertilized eggs and larvae. The results obtained in this study provide opportunities for broodstock management and sex manipulation.

EFFECTS OF THE USE OF 17Î"™-ESTRADIOL FOR <i>Leporinus macrocephalus</i> FEMINIZATION

“…Although sexual steroids have a direct influence on the growth and survival of teleosts (Piferrer, 2001;Lin et al, 2012;Thuong et al, 2017;Alcántar-Vázquez, 2018;Vidal-López et al, 2019), in this study, we did not observe mortality and differences in food intake or growth among treatments and controls. According to Vidal-López et al (2019), estrogens show no anabolic effect in most teleost. This agrees with that we observed in our study, since exposure to estrogen did not cause a significant reduction or increase in growth rate.…”

“…Thus, it is possible that diets supplemented with E 2 increase the circulating levels of this hormone in the treated fish, promoting the gonadal differentiation during the initial development of this species. In fact, this has been seen in several studies (Marín-Ramírez et al, 2016;Juárez-Juárez et al, 2017;Alcántar-Vázquez, 2018;Vidal-López et al, 2019) in which diets supplemented with E 2 promote fish gonadal differentiation.…”

“…The action of E 2 on gonadal differentiation in fish is well documented in the literature (Nagahama and Yamashita, 2008;Thuong et al, 2017;Alcántar-Vázquez, 2018;Vidal-López et al, 2019), and this steroid binds to specific nuclear receptors, which are three main subtypes in fish (α, β1 and β2) (Thomas et al, 2006). Such receptors are expressed at different sites and they also regulate ovarian development and growth (Pankhurst, 2016).…”

“…The production of monosex fish populations is one of the alternatives that can help to boost the cultivation of native fish (Fernandino and Hattori, 2019). Monosex batches provide high economic profitability in production, adding value to the exclusive production of the sex with the best growth rates (Singh, 2013;Budd et al, 2015;Thuong et al, 2017;Alcántar-Vázquez, 2018;Vidal-López et al, 2019). Among the native species of fish considered of great commercial potential, the Leporinus macrocephalus deserves to be highlighted, since it is a large-sized fish, commercially relevant for fisheries and aquaculture (Pereira et al, 2017).…”

“…Leporinus macrocephalus females show higher growth rates than males (Reidel et al, 2004), which is a factor that can be used to increase productivity without the need to enlarge the area of cultivation, and, in addition, to reduce the time of slaughter. The use of endocrine techniques for sexual inversion is widely used in fish production, and it directs the formation of monosex populations for the genus that presents zootechnical advantages (Devlin and Nagahama, 2002;Cnaani and Levavi-Sivan, 2009;Singh, 2013;Örn et al, 2016;Thuong et al, 2017;Alcántar-Vázquez, 2018;Vidal-López et al, 2019). In aquaculture this may represent significant economic gain, adding value to the product if only individuals from the sex with the best growth rates are produced.…”