SPERM MOTILITY PATTERNS OF ATLANTIC COD (GADUS-MORHUA) IN RELATION TOSALINITY - EFFECTS OF OVARIAN FLUID AND EGG PRESENCE

A significantly greater proportion of Atlantic cod (Gadus morhua) sper m were motile in the presence of ovarian fluid and egg compared with s eawater. Sperm mean and maximum swimming speeds were also significantl y greater in the presence of ovarian fluid and egg compared with seawa ter. However, there was no significant difference in path linearity am ong treatments. We also examined the interaction between maternal stim uli (egg and ovarian fluid), time sperm spent in seawater prior to exp osure to each stimulus, and salinity on proportion of motile sperm and their swimming behaviours. Proportion of motile sperm decreased signi ficantly with a decrease in salinity in the presence of both maternal stimuli. Proportion of motile sperm also decreased with time spent in seawater prior to exposure to ovarian fluid but not to an egg. Both me an and maximum swimming speeds were maintained in the salinity range o f 20-30 ppt and only declined significantly at lower salinities (15 an d 17.5 ppt). Mean and maximum swimming speeds decreased with time spen t in seawater. This study demonstrates the importance of maternal fact ors when examining sperm swimming behaviour and highlights the signifi cance of maternal-paternal gametic interactions in understanding ferti lization success.