Fish passage structures enable salmon to bypass dams and barriers, but their design significantly affects the welfare impact on migrating fish navigating these structures.
Fish ladder design is a welfare issue because poorly designed structures require migrating salmon to expend excessive energy attempting to navigate barriers — energy that is critical for successful spawning. Fish that exhaust themselves in ineffective passage structures may complete upstream migration but lack the reserves for successful reproduction. Evidence-based passage design that minimises energy expenditure, provides adequate resting zones and ensures fish can actually locate and use the structure makes a meaningful difference to welfare outcomes for millions of migrating fish annually.