When Ivan Vindheim, CEO of the world's largest salmon company, said earlier this month that a vaccine against one of the more virulent viruses impacting Chile was losing efficacy, it belied a much wider problem.

The Norway-based group's second quarter presentation showed costs at the group's Chile operations rising, in part because the vaccine developed to fight the bacterial infection Piscirickettsia salmonis (SRS) has become less and less effective. Vindheim said the group is looking closely at the issue.

SRS is responsible for economic losses estimated annually at $700 million (€699 million), according to a study published in the scientific journal Biology.