One-half of the injured fish had fractured spines without any associated skin damage; sources of these injuries could not be verified although they probably resulted from avian piscivores and resident salmonids.

Translate to French.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
La moitié des poissons blessés avaient des épines cassées, mais pas de blessures superficielles; la cause de ces blessures n'a pu être vérifiée, mais il est probable qu'elles sont dues aux oiseaux piscivores et aux salmonidés résidants.