Salmon divergence. Salmon eggs are laid in freshwater streams typically at high latitudes. The eggs hatch into alevin or sac fry. The fry quickly develop into parr with camouflaging vertical stripes. The parr stay for six months to three years in their natal stream before becoming smolts, which are distinguished by their bright, silvery colour with scales that are easily rubbed off. Only 10% of all salmon eggs are estimated to survive to this stage. The smolt body chemistry changes, allowing them to live in salt water. While a few species of salmon remain in fresh water throughout their life cycle,
Salmon louse attached to the abdomen. The salmon louse uses its feet to move around on the host or to swim from one host to another. This parasite is one of the major threats to salmon farmers. Salmon are stocked usually for a 14 - 18 month cycle. Salmon farms are an unusual, but ideal environment for the sea lice to breed. The infestations of sea lice in salmon farms increases the number of lice in the rest of the surrounding water dramatically if the eggs from the gravid louse are allowed to disperse. Sea lice can also affect juvenile salmon while