“…Genetic differences between brackish and freshwater populations are also present and have been documented for grayling ( Thymallus thymallus ; Swatdipong, Vasemägi, Koskinen, Piironen, & Primmer, ) and northern pike (Bekkevold, Jakobsen, et al, ). Management advice presented in the scientific literature include identification of the size of management units of pike (Laikre, Miller, et al, ), identification of cod stocks in the eastern Baltic Sea and hybrid zones between stocks in the eastern and western Baltic Sea (Nielsen et al, ; Poćwierz‐Kotus et al, ), genetic differentiation among demersal and pelagic spawners in flounder (Florin & Höglund, ) genetically distinct populations of salmon and trout in separate rivers (and areas within rivers) warranting management of each river flowing into the Baltic Sea separately (Ståhl, ; Ozerov et al, ), and low, but detectable, differentiation among stocks of herring, which promotes management on a more local level than currently applied (Barrio et al, ; Bekkevold, Heylar et al, ; Teacher, André, Jonsson, & Merilä, ). Of specific conservation interest is the identification of sturgeon ( Acipenser oxyrinchus ) populations from Canada suggested as the most suitable source populations for reintroduction programmes in Poland and Germany of the extinct sturgeon (Popović et al, ).…”