Migratory fish - including Atlantic and Pacific salmon, shad, lamprey, and sturgeon - face severe welfare and population impacts from physical barriers to migration. An estimated 1.2 million dams and weirs in the US alone block fish passage, preventing spawning migrations and causing population collapse in once-abundant species. Fish ladders and passes are widely installed but vary enormously in effectiveness; poorly designed passes cause exhaustion, injury, and high mortality in fish attempting passage. Atlantic salmon attempting poorly designed passes show elevated cortisol, depleted energy reserves, and delayed spawning or reproductive failure. Effective passage solutions include nature-like bypasses, rock ramps, and innovative designs including fishways with rest pools. Fish removal and trucking past barriers causes significant handling stress. Dam removal - over 1,200 removals in the US since 1990 - represents the most welfare-positive long-term solution, restoring natural migration corridors.