"We’ve never been closer to the answer than we are now, and the new findings have inspired several new avenues for research that could bring us even closer,” said Nofima researcher Lene Sveen, the lead author of the study.
Photo: Nofima
New scientific findings suggest that a rapid immune reaction in salmon may be crucial for resisting infestation by sea lice, according to researchers at the Norwegian food research institute Nofima.
A recent study, led by Nofima researcher Lene Sveen, has investigated how certain Pacific salmon species respond when sea lice initially attach to their skin. The research indicates that the early stages of this interaction are critical to preventing the parasite from becoming established.
“When the sea louse attaches, some species of Pacific salmon produce a rapid and strong response, and the louse falls off,” said Sveen, who is the lead author of the study, via a Norwegian language press release.
Rather than analysing the fish’s full immune system, the research team focused on the exact location where the lice latch onto the salmon’s skin.
This localised approach revealed that species such as coho salmon trigger a strong inflammatory response within 48 hours of louse attachment. Immune cells quickly move to the affected area, disrupting the parasite’s ability to remain attached.
By contrast, Atlantic salmon exhibited a much weaker response.
“This is exactly where the battle begins,” said Nick Robinson, project leader at Nofima. “If the salmon can respond quickly enough, it can prevent the louse from gaining a foothold.”
The study also observed that other chum and pink salmon - other Pacific species - also show significant resistance to lice. These species have a dense concentration of mucus cells in their skin, which may form an additional barrier against infestation. In some cases, researchers had to sedate the fish in order for the lice to attach during the trial, indicating the parasite’s difficulty in establishing contact under normal conditions.
“This suggests their skin surface is naturally unsuitable for the parasite and that several mechanisms are at play,” Sveen noted.
The findings are part of the international research initiative CrispResist, which includes scientists and industry partners from Europe, North America, and Australia.
The project's goal is to identify why some salmon species are more resistant to lice and apply that understanding to improve resistance in Atlantic salmon through selective breeding or other methods.
The research is funded by the Norwegian Seafood Research Fund (FHF), and partners include the University of Edinburgh, University of Bergen, Deakin University, and major aquaculture companies such as Mowi and Salmar.