Salmon lice are a major problem for fish farmers, costing billions of dollars every year. We previously reported about the issue of sea lice and that there was a concern that salmon, infected with sea lice and escaping from aquaculture could weaken the wild populations. A new report from NOFIMA, analysing peer-reviewed documentation, come to the conclusion that there is no confirmed scientific evidence that escaping, lice-infested salmon can weaken wild populations.

The report, presents a critical review of the factual basis concerning interactions between farmed and wild salmonids as it relates to salmon lice. It evaluates population dynamics, current knowledge about salmon lice, and vectors and dispersion models.

The report states that there is little documentation of lice abundance in a historical perspective, and that there is no evidence of a change in the level of infection of wild salmon at sea. However, it is well-documented that lice infestations in coastal areas near fish farms are more severe during certain times of the year, exposing migrating salmon smolts to greater infection pressure than would be the case without fish farms. The report also states that there is a correlation between the presence of fish farms and increased lice infestations, but that there is no clear cause-and-effect relationship between lice infestations and population size. Unfortunately, there appears to be a trend in science that scientific data presented in the authors’ manuscript do not support the conclusion drawn. The report of NOFIMA also reports the same finding, i.e. there is no evidence of a change in the level of infection of wild salmon at sea.

But there may be a solution to the sea-lice problem, and we take – forgive the pun – a deep-dive: The Norwegian farming company “AKVA group” may have found a solution to this issue. They have developed a method of lowering the net to the depth where the lice do not thrive and the lice separate from the salmon. This method has been tested and has shown positive results, with no lice treatment needed on the salmon taken up from the depth. This method, known as deep farming, also reduces energy consumption by around 70%. The results have caught the attention of other fish farmers.

And again, it is quite obvious that different skills, as well as reskilling and upskilling will be needed, which is where the EIT Food-funded AGAPE project.