The short-term cold storage of blue tilapie (Oreochromis aureus) spermatozoa in HBSS

Abstract

Spermatozoa are an essential part of fertilization in sexual reproduction. Sperm are commonly collected for in vitro fertilization, quality assessment, and research purposes. Sperm cells have incredibly short lifespans which make it difficult for use in aquaculture management and in research. For that reason, it is essential to develop methods for optimal short-term storage of semen. Short-term storage of semen involves temporary cooling of sperm cells (>0 oC), which reduces the metabolic rate and thus extends the lifespan of the cell. That being said, sperm are vulnerable to desiccation as they are highly packed in seminal plasma. Diluents function to reduce the potential for dehydration and decrease sperm density while preventing activation. Extenders are added to semen to mitigate sperm cell damage when stored in cooler temperatures while supplying nutrients to the cells. This is particularly important for work on external fertilizing freshwater fish. Fortunately, there are a variety of diluents and extenders that have already been developed and tested on a variety of freshwater fish species. There has been no work currently done on Blue Tilapia (Oreochromis aureus) in this area. Blue Tilapia are a very important fish for aquaculture and in our lab. The goal of my honours research is to fill this gap and determine if we can successfully store Blue Tilapia semen. I collected semen samples from Blue Tilapia males, diluted it with HBSS, and left samples in the fridge for varying amounts of time. I then examined the effects of the length time in the fridge on sperm percent motility, and swimming velocity. I found that the velocity of spermatozoa of Tilapia in HBSS is not impacted by time in the fridge up to 18 hours. This work opens the door for further research on reproductive biology of Blue Tilapia and improved use for aquaculture and conservation purposes.