(Fertilization of Prochilodus scrofa Steindachner, 1881 with cryopreserved sperm in liquid nitrogen)

Abstract

Aiming at helping the induced spawning, freezing, cryopreservation and fertilization of "curimbatá", Prochilodus scrofa, sperm were studied at the Biology Laboratory of Freshwater Fishes of the Instituto de Pesca in Pirassununga (São Paulo State, Brazil) during the reproductive season of 1986. The sperm from 29 males was collected and assembled in a pool, obtaining the following data of percentage: sperm motility: 90%; sperm concentration: 35.25 x 10⁶/mm³; and live cells percentage by differential staining method: 92.72%. The diluted sperm was frozen and stored in liquid nitrogen (-196°C). After twenty-four hours of freezing, it was thawed and examined under phase-contrast microscopy and presented an average of 35% live spermatozoa. After twenty days, the cryopreserved sperm was thawed and then fertilized, revealing a rate of fertility success of 91.90%; fresh sperm fertility was 90.48% and hatched egg rates were: 77.42% and 84.21%, respectively. After two years of cryopreservation, two fertilization tests were done utilizing fresh eggs, revealing the following results, respectively: 78.01% and 92.68%; 54.78% and 84.27%. For the fresh sperm control the results were: 90.82% and 98.14% of fertilized eggs and 70.79% and 92.41% of hatching eggs. The obtained results suggest that sperm banks should be installed for the studied species.