Knowledge gaps and myths about salmon

Three new research reports show that we know too little about how farmed salmon affect wild salmon, and that it is not communicated clearly enough what we do actually know. Researchers from Nofima are critical about the lack of correlation between the public administration's communication and the actual scientific basis, reports www.megafishnet.com with reference to Nofima.

Senior scientist Solveig van Nes has led a critical review of the factual basis of interactions between farmed and wild salmon as it applies to salmon lice.

"Although salmon lice, like many other factors, can be fatal for individual salmon smolts, there is no documented scientific evidence that salmon lice alone can reduce entire stocks of wild salmon," she says.

"Since it's communicated as a fact that such a reduction occurs, efforts should be placed into finding out if this is actually the case, and to include other possible explanatory models."

In an equivalent report about the genetic influences from escaped farmed salmon on wild salmon populations, scientist Céleste Jacq says:

"To date no published studies have attempted to identify whether the natural selection of Norwegian wild salmon is changed as a result of interactions with farmed salmon. We require knowledge about different local salmon populations, their size, how large an area they cover, and how important local adaptation is before we can reach a conclusion about whether escaped farmed salmon influences precisely these factors."

Scientist Lill-Heidi Johansen was the project manager of an interdisciplinary team of scientists from Nofima, the Norwegian Veterinary Institute and the Institute of Marine Research whose report shed light on what we know about pathogen transfer between farmed and wild fish.

Their main conclusion is that there is little, or no, documented evidence of pathogen transmission between farmed and wild fish, even though in some cases it is established as probable that such transmission occurs. There is also a general lack of knowledge concerning naturally occurring pathogens in wild fish populations.

This research was commissioned by the Fishery and Aquaculture Industry Research Fund (FHF). The Norwegian Institute for Nature Research (NINA) also tendered and conducted evaluations concerning salmon lice and genetic interactions.