They migrate seawards and spend two winters at sea. Some of the salmon migrate to feeding areas probably not beyond the continental shelf and some may actually remain in coastal waters within the influences of the rivers where they were born, but the majority of the salmon migrate well beyond the continental shelf and spend much of their sea life in the rich feeding grounds off west Greenland before returning once again to freshwater to reproduce or spawn. Survival rates for fish in the wild are naturally low, with values of less than 1 percent common but sufficient to sustain the population if not over harvested. Good husbandry practices necessary . . . The life cycle of the cultured salmon reflects the natural cycle, but like any farming enterprise, the implementation of good husbandry practices allows for improved survival and growth over their wild counterparts.
Production begins with the removal of eggs from mature females, a process called stripping.
Eggs are then fertilized with the sperm from male salmon, taken in a similar fashion. The eggs are incubated under controlled conditions in a freshwater hatchery until they hatch. The young salmon, called fry, are nurtured throughout the year until they are physiologically capable of responding to the increasing light conditions of springtime, that is, they smolt. In captivity, the freshwater period seldom exceeds 16 months. Prior to transport to sea cages, the smolts are vaccinated against common salmon diseases, much as children are routinely vaccinated against common human diseases.