Factors affecting the activation, motility and cryopreservation of the spermatozoa of the yellowfin bream, Acanthopagrus australis (Günther)

Abstract

Abstract. The effects of varying temperature, salinity and pH on the activation and subsequent motility of sperm of the yellowfin bream, Acanthopagrus australis (Gunther), were assessed using a linear scale based on the overall activity of the sperm over time. Motility half‐life was calculated using log transformation. Conditions reflecting the natural habitat of the fish, oceanic salinity (1200 mOsM) and slight alkalinity (pH 8‐8‐5), were shown to produce both maximum activation and subsequent motility duration. The half‐life of activated sperm was shown to be greater at 4°C than at 20‐23°C (5·13 min:22·8 min). Storage of freshly stripped semen was shown to be most successful at 4°C with a half‐life of 98·9 min. The cryopreservation of semen was tested using the cryoprotectants glycerol and dimethyl sulphoxide at concentrations ranging from 0·5M to 2·0M, and pre‐freezing equilibration times of 5 and 15 min. Glycerol at 20 M was shown to give significantly superior results. There was no significant difference between sperm activation or sperm half‐life for fresh‐stripped semen and frozen semen, using glycerol at 2·0M as the cryoprotectant. Copyright