Semen cryopreservation of dusky grouper Epinephelus marginatus (Lowe, 1834) (Teleostei, Serranidae)

Abstract

This study aims at developing a protocol of semen cryopreservation of the dusky grouper, Epinephelus marginatus. The effects of interaction between three extenders (pH 6.1 - 7.8 and 8.2), two concentrations of dimethylsulfoxide (DMSO, 5 and 10%) and three freezing speeds (110; 90 and 60°C í­"” min^-1) on the sperm motility and time of sperm motility were analyzed by means of a factorial experiment. A sample of 16 fishes (1,378 ± 358 g, 44 ± 4 cm) collected in the nature was kept in floating net cages and were sex inverted with methyl-testosterone. The semen was frozen using cryogenic slats in nitrogen steam and transferred to liquid nitrogen. The higher sperm motility rate and time of motility (P <0.05) was achieved by combining extender C (pH 8.2) with DMSO (5%) and freezing speed of 60°C min^-1 (P <0.05). These results made possible the implantation of the semen bank of dusky grouper in Brazil, which reduced the need of routine sex inversions for the species reproduction.