Recombinant gonadotropins in meagre (Argyrosomus regius): In-vivo effect on sexually undifferentiated fish

Abstract

Meagre (Argyrosomus regius) is a teleost fish that has experienced an increase in Mediterranean aquaculture production in recent years. To improve productivity, it is necessary to establish a genetic selection program, but the generational interval in meagre is very high (2 and 3 years in males and females respectively). The objective of this survey is to evaluate the effect of specific A. regius single-chain recombinant gonadotropins (rGths) in prepubertal and sexually undifferentiated meagre. For this, 8 treatment groups were established, in which doses of 6, 12 or 18 μg / kg of rFSH or rLH were injected weekly for 3 weeks. Results did not show significant differences in GSI, but they did in plasma E2. Furthermore, early gonadal development was induced with the appearance of oocytes and spermatids in localized regions, while 100% of the fish in the saline group remained sexually undifferentiated. Our results on sexual differentiation show that with rGths therapy 1) males sexually differentiate earlier than females; 2) there is a higher proportion of males; 3) there are intersex fish. This is the first report of the presence of intersex fish and a male skewed ratio in this species. In conclusion, rGths therapy represent a potential solution to reduce the generation interval in prepubertal meagre, but more studies are needed to know how its administration affects during the period of sexual differentiation.