Around 250,000 farmed non-native Atlantic salmon were accidentally released into the wild near Cypress Island, Washington.

Fish farming or pisciculture involves commercial breeding of fish, most often for food, in fish tanks or artificial enclosures such as fish ponds. It is a particular type of aquaculture, which is the controlled cultivation and harvesting of aquatic animals such as fish, crustaceans, molluscs and so on, in natural or pseudo-natural environments. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species produced in fish farming are carp, catfish, salmon and tilapia.

The Atlantic salmon is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Siberian taimen and Pacific Chinook salmon, growing up to 1 m (3.3 ft) in length. Atlantic salmon are found in the northern Atlantic Ocean and in rivers that flow into it. Most populations are anadromous, hatching in streams and rivers but moving out to sea as they grow where they mature, after which the adults seasonally move upstream again to spawn.

On August 19, 2017, a net pen at a salmon farm near Cypress Island, Washington, broke, accidentally releasing hundreds of thousands of non-native Atlantic salmon into the Pacific Ocean. The fish farm was run by Cooke Aquaculture Pacific, LLC. According to the Washington State Department of Natural Resources, inadequate cleaning was likely the primary cause for the pen break; the nets were supporting more than six times their own weight in biofouling. Coastal tribes were hired to fish the escaped salmon. Atlantic salmon farming was later banned in Washington state in reaction to the incident.

Cypress Island is the westernmost part of Skagit County, Washington, and is about halfway between the mainland and offshore San Juan County. It is separated from Blakely Island to the west by Rosario Strait and from Guemes Island to the east by Bellingham Channel. The island has a land area of 5,500 acres (22 km²), and a population of 40 persons as of the 2000 United States Census.