is now. This argument was primarily based on a paucity of bone data in archaeological sites relative to other fish species, and the assertion that historical claims of abundance may have been exaggerated. This argument was later challenged in another paper which claimed that lack of archaeological bone fragments could be explained by salmon bones being rare at sites that still have large salmon runs and that salmonid bones in general are poorly recovered relative to other fish species. Atlantic salmon populations were significantly reduced in the United States following European settlement. The fur trade, timber harvesting, dams and mills and agriculture degraded freshwater habitats and lowered the carrying capacity of most North American streams. Beaver populations were trapped to near-extinction by 1800, and log drives and clear-cutting further exacerbated stream erosion and habitat loss. As timber and fur gave way to agriculture, freshwater Atlantic salmon habitat was further compromised. According to historian D.W. Dunfield (1985) "over half of the historical Atlantic salmon runs had been lost in North America by 1850". As early as 1798, a bill for the preservation of Atlantic Salmon was introduced in Canadian Parliament, to protect populations in Lake Ontario. In the Gulf Region of Nova Scotia it was reported that 31 of the 33 Atlantic salmon streams were blocked off by lumber dams, leading to the extirpation of early-run fish in many watersheds. The inshore Atlantic salmon fishery became a major export of the New World, with major fishing operations establishing along the shores of major river systems. The southernmost populations were the first to disappear. Young salmon spend one to four years in their natal river. When they are large enough (c. ), they smoltify, changing camouflage from stream-adapted with large, gray spots to sea-adapted with shiny sides. They also undergo some endocrinological changes to adapt to osmotic differences between fresh water and seawater habitat. When smoltification is complete, the parr (young fish) now begin to swim with the current instead of against it. With this behavioral change, the fish are now referred to as smolt. When the smolt reach the sea, they follow sea surface currents and feed on plankton or fry from other fish species such as herring. During their time at sea, they can sense the change in the Earth magnetic field through iron in their lateral line. When they have had a year of good growth, they will move