Cryopreservation of Fish Spermatozoa and Ova

Abstract

This paper summarizes historical and current attempts to cryopreserve the gametes of fish, and suggests future uses of cryogenics in fishery biology. Particular attention is given to the evaluation of procedures for collecting, freezing, thawing, and testing spermatozoa. Best methods entail manual stripping for semen, rapid freezing in the vapor of liquid nitrogen, rapid thawing of sperm cells, and fertilization tests with fresh ova. Assessment of the cryoprotective influence of common constituents of fish sperm extenders and life protectors is given. Based on current studies, a simple extender containing two salts and lecithin seems as adequate as more complex diluents. Dimethyl sulfoxide repeatedly provides best protection of salmomd spermatozoa from damage by freezing. Considering current developments, recommendations are made for improving cryoprotective procedures. The paper concludes with speculation on cryopreserving eggs, and on possible areas for further research.