SEASONAL-CHANGES IN THE BIOCHEMISTRY OF SEMINAL PLASMA AND SPERM MOTILITY IN THE OCEAN POUT, MACROZOARCES AMERICANUS

Sperm motility, pH and osmolality of seminal plasma varied throughout the reproductive season spanning the period from June to September. In itially, sperm motility was low, peaked in July and August and then fe ll again towards the end of the spawning season. While the pH of semin al plasma increased from pH 7.4 to 7.9 during the period of spermiatio n, the average seasonal pH (7.78 +/- 0.03) remained close to an experi mentally determined optimum pH range for ocean pout sperm motility (pH 8 - 9). Likewise, although the values for seminal plasma osmolality f ell during the reproductive season, from 416 - 339 mmol kg(-1), the av erage osmolality value 356 +/- 3 was within the optimum for sperm moti lity (300 - 400 mmol kg(-1)). In comparing fluctuations in sperm motil ity with the biochemical composition of ocean pout seminal plasma duri ng the spawning season, this analysis showed that increased Mg++ level s were correlated with the summer period of maximum sperm motility. A seasonal decline in Na+ and Cl- ion levels was reflected in lower semi nal plasma osmolality values.