Brown bears depend critically on salmon runs for the fat reserves needed to survive hibernation — declining salmon populations reduce bear welfare and reproductive success with cascading ecosystem effects.
Brown bears that cannot access sufficient salmon face a welfare deficit that extends into the hibernation period and beyond. Bears entering hibernation in poor condition may lose excessive muscle mass, wake early due to insufficient fat reserves, and face early spring starvation before food sources emerge. Female bears in poor condition produce reduced milk for cubs. The welfare chain linking salmon abundance to bear condition to reproductive success illustrates how ecosystem health and individual animal welfare are inseparable.