Fish are the most numerous vertebrates affected by human activity, with welfare implications at a scale that dwarfs terrestrial animal welfare concerns.
The sheer scale of fish involved in human food systems makes fish welfare one of the most numerically significant welfare issues in existence. If fish experience pain and suffering at even a fraction of the intensity of mammals, the total suffering involved in global fisheries is staggering. This scale makes progress in fish welfare potentially among the highest-impact areas of welfare improvement available.