Biological control of sea lice using wrasse and lumpfish has grown rapidly, but cleaner fish welfare is a major emerging concern. Understanding the trade-offs helps evaluate the approach.
The biological sea lice control approach has transferred welfare problems from salmon to cleaner fish — smaller, less visible animals that receive significantly less welfare attention. Wrasse and lumpfish placed in salmon cages die at high rates from disease, predation by salmon, cold stress, and overcrowding. The suffering experienced by these animals during their short, difficult lives in cage environments is substantial but largely invisible to consumers and regulators. The conservation dimension adds another layer: wild-caught wrasse populations may be suffering unsustainable removals in some Norwegian coastal areas. A welfare-positive approach to sea lice management would prioritize prevention (cage design, genetics) and ensure that any biological control approach incorporates cleaner fish welfare as a primary consideration alongside salmon welfare.