By-catch
By-catches are fish that are caught but not the intended target species in fishing. The term is used in both commercial and recreational fishing. For example, if you are target coho salmon in a river but chum salmon are caught, then chum salmon are by-catches. By-catches are usually not targeted because they are protected and required to be released. If the species is protected, selective fishing techniques are required to be used to reduce the number of by-catches.