Dolphin and Salmon

Sometimes people may feel sad when they know twenty-three thousand of dolphins are being killed everyday but they may feel okay there are much more Salmon being killed everyday, why? Is it because dolphin is cute but salmon are not? Is it because dolphin is facing extinct but salmon are not? Isn't it "funny"? You eat chicken but you don't feel sad to chicken, but you don't want to eat monkey or dolphin.