ASSESSMENT OF SPERM CONCENTRATION AND MOTILITY IN TURBOT (SCOPHTHALMUS-MAXIMUS)

Several techniques allowing an assessment of turbot sperm quality in terms of concentration and motility were assessed. They included techniques adapted to experimental objectives as well as practical gross evaluation techniques which could be used easily in production operations. Sperm concentration could not be accurately estimated by spermatocrit. Counting in a Malassez's cell was an accurate but time-consuming technique. Sperm concentration could be evaluated by spectrophotometry at a 420 nm wavelength. Samples with a viscous aspect had a higher concentration (54.6 x 10(9) +/- 5.4 spermatozoa/ml) than liquid ones (20.0 x 10(9) +/- 2.4). Increasing dilution from 1:10 to 1:1000 affected sperm motion in terms of activation and duration of movement. At dilution 1:10, sperm motility presented a linear decrease with time. Hence, the duration of movement could characterize sperm motion. Using these method, sperm samples collected during the first stripping of the natural spawning season were described (volume 1.6 +/- 0.2 ml; concentration 38.3 x 10(9) +/- 5.9 spermatozoa/ml; motility 6.06 +/- 1.08 min.s.; and spermatocrit 40.4 +/- 5.8%).