Coho salmon and silver salmon refer to the same species of fish, Oncorhynchus kisutch. The term “silver salmon” is a widely used common name for the Coho, often employed in commercial and recreational fishing contexts. This article explores the characteristics of this Pacific salmon species and the reasons for its dual naming.
The Coho Salmon: A Single Species with Many Names
The Coho salmon, scientifically known as Oncorhynchus kisutch, is an anadromous species, meaning it hatches in freshwater, migrates to the ocean to mature, and then returns to freshwater to spawn. Native to the North Pacific Ocean, its range extends along the coasts of North America from Alaska to central California, and across to Asia, including Japan and eastern Russia. Some populations have also been introduced to the Great Lakes.
During their ocean phase, Coho salmon have silver sides and dark metallic blue or greenish backs. They possess small black spots on their back and the upper lobe of their tail fin. Adults typically weigh 8 to 12 pounds and measure 24 to 30 inches, though some can reach 36 pounds and over 40 inches. A distinguishing feature is their white gums at the base of their teeth, which helps differentiate them from other salmon.
The Coho salmon’s life cycle spans three to four years. Juveniles spend one to two years in their natal freshwater streams, feeding on insects and plankton. They then migrate to the ocean, spending 1.5 to 2 years feeding on smaller fish like herring and anchovies, and growing significantly. When mature, they migrate back to their original freshwater spawning grounds between September and March. After spawning, all Coho salmon die.
Why the Terminology Causes Confusion
Multiple common names for a single species, like Coho and silver salmon, often cause confusion. One reason for the “silver salmon” moniker is the fish’s silvery appearance during its ocean phase. This descriptive naming is common in biology, where species are often named based on physical traits, behaviors, or habitat.
Regional variations also contribute to naming complexity. Different areas or fishing communities adopt different common names for the same fish, creating a patchwork of terminology. Unlike common names, scientific names are standardized globally to avoid ambiguity.
Numerous distinct salmon species, each with their own common names, also add to public confusion. For instance, other Pacific salmon species have alternative common names, such as Chinook salmon (“King salmon”) or Sockeye salmon (“Red salmon”). This pattern of multiple common names within the salmon family can make it challenging to discern whether two names refer to the same species or different ones.