Cryopreservation of sperm of farmed European eel Anguilla anguilla

Sexual maturation and sperm release were induced in farmed European eels Anguilla anguilla kept exclusively in fresh water by using two dosages of human chorion gonadotropin (100 International Unit (IU)-Group one and 250 IU/individual per week-Group two). Sperm release took over 13 wk in both groups. The quality of sperm was investigated on the eighth, ninth, and tenth wk. The average cell densities were 0.94 +/- 0.4 x 10(10) (Group one) and 0.93 +/- 0.6 x 10(10) (Group two) spermatozoa/mL. The estimated motility of eel sperm was 33, 55, and 49% on the eighth, ninth, and tenth wk of treatment, respectively. The estimated average motility of samples selected for cryopreservation was 73 +/- 10%, while the post-thaw motility of cryopreserved samples was 36 +/- 11%. The extender originally developed for common carp sperm crypreservation together with methanol as cryoprotectant was found suitable for the cryopreservation of European eel sperm.