Degraded river habitats reduce freshwater fish welfare through chronic stress, impaired migration, and loss of spawning and feeding grounds; habitat restoration delivers measurable welfare and population benefits.
Freshwater fish in degraded rivers experience cumulative welfare harms. Barriers to migration prevent access to upstream spawning grounds, forcing fish into futile and exhausting attempts to ascend impassable barriers. Oxygen depletion from agricultural runoff causes mass mortality events where fish suffocate. Temperature increases from reduced riparian shade push salmonids beyond their thermal tolerance. The chronic stress of degraded habitat suppresses immune function and reproductive success across entire river systems.