Preliminary studies on the cryopreservation of spermatozoa in the fresh water fish common carp (Cyprinus carpio L.)

Common carp [Cyprinus carpio (C. carpio)] is an economically important fish species cultured mostly in Asia and Europe. Global production of farmed common carp was about 6.14% (3 172 488 tonnes) of the total world aquaculture production[1]. Artificial insemination can be applied to increase the production to meet this demand due to exploitation of natural stocks. Cryopreservation is a valuable technique to assist in the genetic improvement of cultured stocks as well as providing a continuous supply of good quality sperm for artificial insemination. Successful storage of fish sperm in liquid nitrogen has been reported for more than 200 species[2], but the protocol varies with species. Extender composition, cryoprotectant concentration, and freezing method are known to affect cryopreservation success[3,4]. Cryopreservation of common carp sperm using saline extenders and dimethyl sulfoxide (DMSO) or dimethylacetamide (DMA) produced variable results on post-thaw sperm motility and/or fertilization and hatching success[5-7]. However, evaluation of the various cryopreservation methods is hindered by the different extenders, cryoprotectants and freezing methods that have been used. In contrast, damaging effects to carp sperm by equilibration with DMSO were observed[8], and other comparative DMSO studies showed a better suitability of methanol and glycerol and DMA for freezing of carp sperm[9,10]. The usefulness of the latter cryoprotectants for cryopreservation of fish sperm was first reported for PEER REVIEW ABSTRACT