Bluebacks: The history and biology of sea-run trout

The term ‘blueback’ refers to salmon and sea-run trout that possess blue backs and white bellies upon exiting the ocean. This coloration serves as camouflage against predators from both above and below. As these anadromous fish transition from salt to fresh water, they undergo physical transformations, including the loss of salt-water scales and changes in color to match riverbed rocks for spawning.

Sea-run cutthroat are frequently referred to as bluebacks and are considered an indicator of healthy salmon runs. Historically, the Lake Ozette sockeye was also known by this name, though it is now classified as a threatened or endangered species. On the Olympic Peninsula, the Beardslee trout of Lake Crescent were also called bluebacks, named after Admiral Lester Beardslee, who visited the area with the U.S. Navy’s Pacific Squadron in 1895.