Cryopreservation of Embryos and Oocytes of South American Fish Species

Abstract

The importance of animal genetic resources for wildlife maintenance as well as farming production has become more and more evident in recent years. Fish stocks are globally threatened mainly due to overfishing and environmental pollution. Cryopreservation of aquatic germplasm brings the possibility of preserving the genome of endangered species, increasing the representation of genetically valuable animals for farming purposes and avoiding genetic losses through diseases and catastrophes. In fish, successful cryopreservation of semen from many species has been well documented and cryopreserved semen has been used for reproduction of many wild and farmed species. Attempts to cryopreserve fish embryos have been conducted over the past three decades, nevertheless successful cryopreservation protocol for long-term storage still remains elusive. In this chapter we cover the cryobiology applications on assisted reproduction for fish farming, focused on embryo and oocyte cryopreservation. Our research group has been working in this area for more than 10 years and the chapter shows the main results that we have achieved from researches on embryos cryopreservation. The barriers that have been identified as a hamper for successful cryopreservation and the sensitiveness of tropical fish embryos to low temperature exposure are also detailed here. Recently, researches have reported that the use of oocytes may offer some advantages when compared to fish embryos, improving the chances of a successful cryopreservation. On this point, the chapter presents the most recent achievements in oocytes cryopreservation from South American fish, new trends and future works on this area.