Many animals experience pain, anxiety and suffering, physically and psychologically, when they are held in captivity or subjected to starvation, social isolation, physical restraint, or painful situations from which they cannot escape. Even if it is not the same experience of pain, anxiety, or suffering undergone by humans- or even other animals, including members of the same species- an individual's pain, suffering, and anxiety matter.
We generally accept that it's natural for carnivorous wild animals to kill other animals in order to live. But people don't often think (or even know) about the extraordinary and unnatural suffering that humans inflict on the animals that we freely harvest for food, with the help of modern high technology and the animal food sciences.
Hunting and fishing involve killing animals with devices (such as guns) for which the animals have not evolved natural defenses. No animal on earth has adequate defense against a human armed with a gun, a bow and arrow, a trap that can maim, a snare that can strangle, or a fishing lure designed for the sole purpose of fooling fish into thinking they have found something to eat