Fucus serratus (Toothed Wrackl Serrated Wrack; Toothed Rockweed) is a brown seaweed native to rocky intertidal and shallow subtidal zones from Norway to Spain, and the central Baltic to Poland. This seaweed has been introduced to Iceland, with a first record in 1903. In North America, it was collected once in 1851, in Newburyport, Massachusetts, but did not become established. It was collected in Pictou, Nova Scotia, on the Gulf of St. Lawrence in 1861, and well-established by 1869, By 1902, it had spread eastward to Inverness, on the Gulf side of Cape Breton Island, and westward to Pugwash on the Northumberland Strait.. It was also found at Pirate Harbor, on the Strait of Canso, connecting to the Atlantic coast of Nova Scotia. On the Atlantic coast of Nova Scotia ,it has spread at spot locations, reaching the Yarmouth area, Nova Scotia, on the Gulf of Maine by 1948. Records from the coast Maine. An attempt was made before 1902 to transplant this seaweed to Pelham Bay, New York City, but this transplant was apparently unsuccessful. Pictou was a major landing site for immigrants to Canada, and the apparent introduction site for Fucus serratus and the Common Periwinkle (Littorina littorea) Genetic analysis and historical records suggests that both species were introduced from Ireland and Scotland, probably in the solid ballast of ships carrying immigrants.