runs. Migration of adult Atlantic salmon may be limited by beaver dams during periods of low stream flows, but the presence of juvenile salmon upstream of the dams suggests they are penetrated by parr. Downstream migration of Atlantic salmon smolts was similarly unaffected by beaver dams, even in periods of low flows. In a 2003 study, Atlantic salmon and sea-run brown trout spawning in the Numedalslågen River and 51 of its tributaries in southeastern Norway was unhindered by beavers. In a restored, third-order stream in northern Nova Scotia, beaver dams generally posed no barrier to Atlantic salmon migration except in the smallest upstream reaches in years of low flow where pools were not deep enough to enable the fish to leap the dam or without a column of water over-topping the dam for the fish to swim up. The importance of winter habitat to salmonids afforded by beaver ponds may be especially important in streams of northerly latitudes without deep pools where ice cover makes contact with the bottom of shallow streams. In addition, the up to eight-year-long residence time of juveniles in freshwater may make beaver-created permanent summer pools a crucial success factor for Atlantic salmon populations. In fact, two-year-old Atlantic salmon parr in beaver ponds in eastern Canada showed faster summer growth in length and mass and were in better condition than parr upstream or downstream from the pond. Relationship to humans Atlantic salmon is a popular fish for human consumption and is commonly sold fresh, canned, or frozen. Wood and stone weirs along streams and ponds were used for millennia to harvest salmon in the rivers of New England. European fishermen gillnetted for Atlantic salmon in rivers using hand-made nets for many centuries and gillnetting was also used in early colonial America. In its natal streams, Atlantic salmon are considered prized recreational fish, pursued by fly anglers during its annual runs. At one time, the species supported an important commercial fishery, but having become endangered throughout its range globally, wild-caught Atlantic salmon are now virtually absent from the market. Instead, nearly all are from aquaculture farms, predominantly in Norway, Chile, Canada, the UK, Ireland, Faroe Islands, Russia and Tasmania in Australia. Aquaculture Adult male and female fish are anaesthetised; their eggs and sperm are "stripped" after the fish are cleaned and cloth dried. Sperm and eggs are mixed, washed, and placed into freshwater. Adults recover in flowing,