THE AGING PHENOMENON OF TURBOT SPERMATOZOA - EFFECTS ON MORPHOLOGY, MOTILITY AND CONCENTRATION, INTRACELLULAR ATP CONTENT, FERTILIZATION, AND STORAGE CAPACITIES

The deleterious effect of the ageing phenomenon of turbot spermatozoa was investigated in relation to the sampling date. Spermatozoa with a low or highly condensed chromatin and a middle piece containing numero us or a few vesicles were observed simultaneously 80 and 47 days befor e the beginning of the spawning period of the females. The middle piec e of spermatozoa contained few vesicles, 39 days after the end of the reproductive period. At the same date, some spermatozoa appeared in wh ich the plasma membrane was broken. Sperm motility, assessed just afte r collection in terms of arbitrary motility scores from 0 to 5, was si gnificantly increased both at 10 and 60 s post-activation, for samples collected 18 days after, 25 days before and 9 days after the beginnin g of the spawning period of the females, respectively compared to samp les collected 6 days before, 55 days after and 88 days after the end o f this period. A lower short-term storage capacity was recorded at 10 and 60 s post-activation for sperm samples collected 6 days before and 88 days after the end of the reproductive period, respectively compar ed to 18 days and 9 days after the beginning of the spawning period. A t 60 s post-activation, a higher motility of thawed spermatozoa was ob served for samples collected 5 days before the beginning of the spawni ng period (motility recovery index: 86.4 +/- 19.4%) compared to 71 day s after the end of this period (55.0 +/- 12.0%). The fertilizing capac ity of sperm samples collected 61 days after the end of the spawning s eason (66.1 +/- 14.6%) was significantly lower than that recorded for samples collected 34 days after the beginning of the spawning period ( 75.2 +/- 9.6%). On the contrary, there was no significant decrease in endogenous ATP content (31 days after the beginning of the spawning pe riod, 14.53 +/- 0.84; 48 days after the end of this period, 10.75 +/- 5.26 nmol 10(-8) spermatozoa). Furthermore, sperm concentration signif icantly increased between the same dates (respectively 3.3 +/- 0.8-9.4 +/- 4.8 x 10(9) spermatozoa ml(-1)). (C) 1998 The Fisheries Society o f the British Isles.