Lumpsuckers (Cyclopterus lumpus) are used in salmon aquaculture as biological alternatives to chemical treatments against sea lice. Deployed in salmon pens to consume lice from salmon, they face severe welfare challenges in a system fundamentally alien to their natural biology.
Lumpsuckers used as cleaner fish suffer from conditions poorly matched to their natural biology: salmon pens provide no rocky substrate for attachment, no appropriate diet, and expose them to predation by salmon if lice numbers are insufficient. High mortality within months of deployment indicates chronic welfare compromise. Unlike wrasse (another cleaner fish species), lumpsuckers appear less able to adapt to salmon pen conditions and show characteristic welfare signs including emaciation, injury, and abnormal behaviour. The welfare cost of lumpsucker cleaner fish programs must be weighed against the alternative of chemical sea lice treatments, which have their own environmental and fish welfare implications. Mechanically harvesting sea lice using snorkel technology or lasers represents a non-animal welfare alternative.