Although North American salmon were released many times since 1924 into Chilean waters, investigators trace the origins of the naturalized fish mainly to a period of ocean ranching lasting from 1978 to 1989. Fish hatcheries at two locations in southern Chile raised and released hundreds of thousands of chinook smolts into streams flowing into the Pacific Ocean. Their stocks came from the Cowlitz and Kalama Rivers, both tributaries of the Columbia River in southwest Washington state.
Farmed salmon that escaped from net pens during the 1990s are another possible source of the naturalized runs. This study's authors nevertheless assert that fish farm fugitives haven't contributed much to the wild Chilean populations.
Chinook salmon rapidly colonise South American rivers
US - It's taken less than thirty years for chinook salmon that were let loose in South America to establish spawning runs along 1500 kilometres of the South Pacific coast. Salmon from these introductions have also swum through the Strait of Magellan and into the Atlantic Ocean.