Post-thaw storage of sperm from various salmonid species

Summary The effects of post‐thaw storage on the motility and fertilizing capacity of cryopreserved sperm were investigated in four salmonid species, including the Adriatic grayling (Thymallus thymallus; five males), rainbow trout (Oncorhynchus mykiss; six males), marble trout (Salmo marmoratus; five males) and the brown trout (Salmo trutta m. Fario; six males). The sperm of rainbow trout and marble trout was cryopreserved in the presence of either methanol or dimethyl‐sulfoxide (DMSO) as a cryoprotectant; for the sperm of the Adriatic grayling and brown trout, only methanol was used. A 1‐h storage of sperm did not reduce the fertilizing capacity of the three species, whereas in the marble trout a gradual decrease in the percentage of eyed eggs in parallel with post‐thaw storage time was observed. The use of methanol was found to result in higher fertilization than that of DMSO in the rainbow trout and marble trout. Remarkably high post‐thaw motility expressed in % motile cells was observed following post‐thaw storage of brown trout sperm for 10 (53 ± 12%) or 60 (56 ± 15%) min. The results indicate that immediate use of cryopreserved sperm for fertilization following thawing is not mandatory to attain successful fertilization.