The fresh and frozen Atlantic salmon sold in Costco warehouses under its Kirkland Signature brand is exclusively farmed rather than wild-caught. Because commercial fisheries do not capture wild Atlantic salmon in quantities sufficient to sustain global retail supply chains, virtually all Atlantic salmon found in mainstream supermarkets originates from aquaculture operations located in countries like Norway, Chile, Scotland, Canada, or Iceland. Costco sources its farmed salmon from certified suppliers that adhere to recognized aquaculture stewardship standards, though consumers seeking wild-caught options must specifically look for Pacific species like Sockeye or Coho.