Sperm characteristics of wild and captive lebranche mullet Mugil liza (Valenciennes, 1836), subjected to sperm activation in different pH and salinity conditions

In this article we describe basic aspects of the sperm biology of lebranche mullet (Mugil liza) in the wild and in captivity, in particular assessing the effects of salinity (0, 10, 20, 30, 35, 40, 50 and 60 g L-1) and pH (6, 7, 8, 9 and 10) on sperm motility. Our results indicate that the highest percentage of motility was recorded with salinity 34.6 g L-1 (95 +/- 10%) and the longest motility time was obtained with a salinity of 34.8 g L-1 (189 15 s). Variations in the salinity between 30 and 35 g L-1 did not produce any significant alterations in sperm motility; however salinities of 20 and 50 g L-1 produced a significant loss of sperm motility. The highest percentage of motility was obtained at pH 8.5 (93 +/- 12%), and the longest motility period at pH 8.7 (218 13 s), while pH lower than or equal to 7 and equal to 10 both produced a significant loss in sperm motility. A positive correlation was found between pH/salinity and the motility percentage (R-2 = 0.94 and R-2 = 0.97) and motility time (R-2 = 0.86 and R-2 = 0.98). In seminal and morphometric parameters, statistically significant differences were observed in semen volume, sperm density, plasma membrane integrity and sperm morphometry between the groups studied, showing that the characteristics of the fish have a direct influence on sperm quality. The information generated in this research will be useful for developing biotechnology tools for the effective management of Mugil liza gametes