Scientists from Bangor University have revealed male farmed salmon are "less sexy" than their wild counterparts.
The new research found male farmed salmon have smaller "jaw hooks", making them less attractive to potential mates.
The findings are part of a wider project researching the differences between wild, farmed and "hybrid" salmon.
Lead author on the paper, William Perry, said the findings suggest farmed salmon are less likely to be successful in the wild.
The 24-year-old PhD student added: "They are also less likely to return from the ocean to freshwater rivers to spawn".
Jaw hooks in salmon are a secondary sexual trait - like manes on male lions and colourful feathers on male peacocks. It's thought the traits help animals compete for a mate.
The Bangor researchers said because farmed salmon are kept in enclosures, males do not have to compete for females, so don't need adaptations like large jaw hooks.