Effect of successive milt collection on sperm quality and reproduction of wild and cultured endangered caspian brown trout, Salmo trutta

In the present study, the effect of successive milt collection was investigated on spermatological parameters and reproduction successes of wild and cultured endangered caspian brown trout. The milt collection was done 3 times with two weeks intervals. After milt collection, amount of milt was allocated for milt quality evaluation and reminders used for fertilization. According to results, in wild fish, the values of fertilization rate, eyeing rate, hatching rate, milt volume and duration of sperm motility decreased during successive stripping (P<0.05) while the spermatocrit, sperm density did not show significant differences (P>0.05). Also, the percentage of abnormal spermatozoa increased during successive stripping in wild fish (P<0.05). The perm density, spermatocrit and survival percent of larvae did not show significant changes during successive stripping (P>0.05). In cultured fish, similar results were observed about fertilization rate, milt volume and duration of sperm motility (P<0.05), although the eyeing rate, hatching rate, spermatocrit and sperm density values did not show significant changes during successive stripping (P>0.05). Also, the survival rates of larvae were statistically different between second and third stripping (P<0.05). In conclusion, our results showed that the successive milt collection has a significant influence on milt quality and reproductive efficiency of male caspian brown trout, with the best milt being available at the first stripping.