It works! Lumpfish can significantly lower sea lice infestation in large-scale salmon farming

• Published in: Biology Open
• Main Authors: Imsland, Albert Kjartan Dagbjartarson, Hanssen, Anna, Nytrø, Ane Vigdisdatter, Reynolds, Patrick, Jonassen, Thor Magne, Hangstad, Thor Arne, Elvegard, Tor Anders, Urskog, Tonje Cecilie, Mikalsen, Bjørn
• Format: Text
• Language: English
• Published: The Company of Biologists Ltd 2018
• Subjects: RESEARCH ARTICLE; Atlantic salmon
• Online Access: http://bio.biologists.org/cgi/content/short/7/9/bio036301; https://doi.org/10.1242/bio.036301

To assess the efficacy of lumpfish grazing on attached sea lice on Atlantic salmon, six large-scale sea cages, (130 m circumference, 37,688 m3 volume) each stocked with approximately 200,000 salmon 0+ smolts, were stocked with a 4, 6 and 8% density (8000, 12,000 and 16,000, respectively) of lumpfish. The sea cages without lumpfish acted as controls. Sea lice infestation levels on the salmon were monitored weekly and bi-weekly from 6 October to 17 May the subsequent year. Mortality of the lumpfish rose with decreasing sea temperatures to around 0.8% week−1 and did not vary between the lumpfish groups. There were clear signs of lumpfish grazing on sea lice, with significantly lower average levels of chalimus, pre-adult and adult female L epeophtheirus salmonis and Caligus elongatus sea lice per salmon. Lumpfish in the high density (8%) group reduced the mature female L . salmonis to levels equal to or lower than the counts recorded prior to the start of the study. Overall, the present results indicate that lumpfish are a suitable cold-water option for biological delousing of Atlantic salmon in large-scale production conditions.