By-catch are species caught in a fishery which intended to target another species, as well as reproductively-immature juveniles of the target species. The OECD (1997) defines bycatch as Total fishing mortality excluding that accounted directly by the retained catch of target species. According to Alverson et al. (1994) there are at least four different uses of the word by-catch in fisheries. By-catch may refer to catch which is retained and sold but which isn't the target species for the fis… (More on Bycatch)