The smoltification process that prepares salmon for ocean entry is a period of significant physiological stress — farm management during this transition has important welfare implications.
Smoltification represents a critical welfare window in salmon aquaculture. The profound physiological transformation required to switch from freshwater to saltwater osmoregulation places significant metabolic demands on fish during a period when they are simultaneously transitioning to a new environment and facing novel challenges including sea lice and pathogens. Management of artificial lighting regimes to induce smoltification at the optimal time is important for both production and welfare outcomes. Fish that undergo premature or incomplete smoltification experience osmotic stress and compromised physiological function. Post-smolt welfare in the first weeks of sea entry is particularly important, as osmoregulatory competence is still developing. Monitoring behavioral indicators of welfare during this transition allows early intervention when problems develop.