Rainbow trout are the most commonly farmed salmonid in Europe and North America, and their welfare in aquaculture is affected by stocking density, water quality, handling stress, and slaughter methods.
Trout welfare is influenced by decisions made throughout the production cycle. High stocking densities cause chronic low-level stress that compromises immune function and increases disease susceptibility. Handling events including grading, vaccination, and transport cause acute stress responses measurable through cortisol elevation. The slaughter method matters enormously — ice slurry immersion causes prolonged conscious suffering, while effective electrical or percussive stunning provides rapid insensibility. The existence of better alternatives makes ongoing use of inhumane slaughter methods an industry choice rather than a practical constraint.