Sperm morphometry in the Atlantic salmon

This study sampled sperm from wild Atlantic salmon to explore relationships between sperm form and function. Detailed measurements of sperm morphometry (head, flagellum and total length) and sperm activity (longevity and % motility) were made from 24 reproductively active males (13 anadromous and 11 mature parr) on two occasions post-stripping. There was significant between-male variance in total sperm length but this variance was not related to body size. Despite this variance in sperm length, no relationships were found between a male's sperm activity (longevity or % motility) and his sperm length. There were also no relationships between sperm head length and flagellar length, and no evidence for a trade-off between sperm length and numbers. It is suggested that the significant between-male variance in sperm morphometry supports diploid control of spermatogenesis: haploid expression of sperm phenotype would be manifested as profound variance within (and not between) each male's spermatozoal characteristics.