The walleye (Sander vitreus, synonym Stizostedion vitreum), also called the walleyed pike,[3] yellow pike, yellow pikeperch or yellow pickerel,[4] is a freshwater perciform fish native to most of Canada and to the Northern United States. It is a North American close relative of the European zander, also known as the pikeperch. The walleye is sometimes called the yellow walleye to distinguish it from the blue walleye, which is a color morph that was once found in the southern Ontario and Quebec regions, but is now presumed extinct.[5] However, recent genetic analysis of a preserved (frozen) 'blue walleye' sample suggests that the blue and yellow walleye were simply phenotypes within the same species and do not merit separate taxonomic classification.[6] In parts of its range in English-speaking Canada, the walleye is known as a pickerel, though the fish is not related to the true pickerels, which are members of the family Esocidae.[7] It is also sometimes called a dory in British English (and its common name in French is the similar doré—meaning golden or gilded), although this name is also used for various other species.[8] Walleyes show a fair amount of variation across watersheds. In general, fish within a watershed are quite similar and are genetically distinct from those of nearby watersheds. The species has been artificially propagated for over a century and has been planted on top of existing populations or introduced into waters naturally devoid of the species, sometimes reducing the overall genetic distinctiveness of populations.