ABSTRACT
The concentration of gametes affected fertilization success. The sperm concentrations of 10, 102 and 103 cells/ml had the maximal fertilization rates (Figure 1). Fertilization rates were higher for gametes fertilized within 2 h post-spawning and decreased after 3 h (Figures 2 and 3). There was a significant influence of spermegg contact time on fertilization rates (Figure 4). Fertilization rates were high and deformation rates low when fertilized eggs were washed right after eggs were inseminated at sperm concentrations of 103 cells/ml. Washing the fertilized eggs 3 times resulted in better fertilization rates (Figure 5). The highest post-thaw sperm motility was obtained when sperm was frozen at a rate of -12 or –15ºC/min to the transition temperature –30ºC (Table 1). The transition temperature of –90ºC seemed to be more beneficial than other tested temperatures (Table 2). The optimal thawing condition for the sperm of small abalone was in a water bath at 70ºC for 1 min. Small abalone sperm cryopreserved in DMSO resulted in fertilization rates between 7 to
48%, depending on the sperm concentration (Figure 6). The fertilization capacity of the frozen sperm is about half that of the fresh sperm using the same sperm concentration of 103 (Figs. 1 and 6).
