Linked from
The 24 pages that link to Anadromy, each with the reason it gives.
Arctic charRelated: Some Arctic char populations feed at sea and return to freshwater to spawn.
Sea lampreyRelated: Many sea lampreys feed in marine waters before returning to rivers to spawn.
ClupeidaeRelated: Several shads in Clupeidae use this migration pattern to reach spawning grounds.
Brown troutRelated: Sea trout exhibit this pattern, while many brown trout remain in freshwater.
CoregonusRelated: Some Coregonus populations move between marine and freshwater habitats.