Sperm characteristics of wild‐caught and hatchery‐reared turbot, Scophthalmus maximus, originated from the Black Sea.

In this study sperm characteristics (sperm volume, sperm volume per kg fish, spermatocrit, sperm concentration, pH, and sperm motility) of wild‐caught and hatchery‐reared turbot (Scophthalmus maximus), originated from the Black Sea population, were assessed. In this regard, two different trials were conducted. On the Trial‐I, sperm characteristics of wild‐caught and hatchery‐reared turbot (4‐, 7‐, and 10‐year‐old) were comparatively investigated during the spawning season (May), on the Trial‐II, monthly variations of sperm characteristics of hatchery‐reared turbot (4‐year‐old) were investigated. On the Trial‐I, a positive correlation between body weight and sperm volume was recorded. Significant differences were noted in sperm volume, and sperm concentration, however, there was no significant difference between the groups in terms of sperm volume per kg of body weight, spermatocrit, and pH. The sperm motility showed a significant decrease after the 15 minutes post‐activation in all the specimens. The active spermatozoa rate of the wild‐caught turbot was 44% at 15 minutes post‐activation, whereas it was 16%, 13%, and 64% for 4‐, 7‐, and 10‐year‐old turbot, respectively. The average motility duration of the wild‐caught turbot spermatozoa was significantly longer compared to hatchery‐reared turbot despite having a comparatively lower initial motility rate than hatchery‐reared turbot. On Trial‐II spermiation duration of hatchery reared Black Sea turbot was determined as 6 months, starting from February until the end of July. The highest and the lowest sperm volume, and sperm volume per kg were recorded in June and July, respectively. Significant differences were determined between the months in terms of sperm volume per kg, sperm volume, spermatocrit, and sperm concentration, however, the pH was similar. These results demonstrate the sperm characteristics of wild‐caught and hatchery‐reared Black Sea turbot were different in the spawning season (May) and the potential spermiation season was between February and July. [ABSTRACT FROM AUTHOR]