Brown Trout (Salmo trutta) is a predominantly freshwater fish, but also has anadromous (sea-running) populations, referred to as 'Sea Trout'. Brown Trout (Salmo trutta) have a broad range in Eurasia from Iceland, Great Britain, to North Africa and Pakistan. In the southern part of its native range, it is confined to higher elevations, but sea-run populations occur south to northern Spain. Brown Trout are one of the world's most popular sport fish, and have been stocked around the world. Brown Trout were first stocked in North America in 1883, in the Pere Marquette River, Michigan and soon were widely introduced in North America by the United States Fish Commission (USFC) and many state agencies, and, in many states, are stocked annually to the present day. This species has been stocked in 47 U.S. states, and is considered established in 36 states. Sea-Running populations of Brown Trout are known on the Atlantic Coast from Labrador to New Jersey, but many of these are dependent on stocking in coastal streams. On the Pacific Coast, sea-running populations are known in British Columbia, and have been suspected to occur in the Columbia River, the Trinity River, and the San Francisco estuary as well. Introduced anadromous populations are known from Hokkaido, Japan, South America, southern Australia, New Zealand, and sub-Antarctic islands. Introduced Brown Trout have displaced some native salmonid populations including sea-run Brook Trout (Salvelinus fontinalis) in New England, and Bull Trout (Salvelinus confluentus) in California.