When discussing the world's most iconic anadromous fish, the question "how many species of salmon are there" appears simple but requires a nuanced answer. At the broadest taxonomic level, there are five primary species of Pacific salmon belonging to the genus *Oncorhynchus*. These are consistently recognized as the Chinook, Coho, Sockeye, Pink, and Chum salmon, each occupying distinct ecological niches and fisheries across the North Pacific. However, the biological reality is more intricate, involving numerous subspecies, regional variations, and a distinct sixth species found in the Atlantic.
The Five Pacific Salmon Species
Understanding the core five species is fundamental to answering the question of salmon diversity. These fish share a similar anadromous lifecycle—born in freshwater, migrating to the ocean to grow, and returning to their natal streams to spawn—but they differ significantly in size, flavor, texture, and spawning behavior. This variation ensures the resilience of the genus *Oncorhynchus* and supports a wide range of commercial and recreational fisheries throughout Alaska, British Columbia, Washington, Oregon, and Northern California.
Chinook Salmon
Known also as King salmon, Chinook (*Oncorhynchus tshawytscha*) is the largest of the Pacific species, with some specimens reaching over 100 pounds. They are prized for their high fat content, which creates a rich, buttery texture and makes them a favorite among commercial and sport fishermen. Chinook are the first to spawn in the spring and are considered an indicator species for the health of the entire ecosystem due to their position at the top of the food web.
Coho Salmon
Coho salmon, or Silver salmon (*Oncorhynchus kisutch*), are the acrobats of the salmon world. They are known for their spectacular leaping ability when navigating upstream obstacles. Coho are generally smaller than Chinook but offer a milder, sweeter taste with a medium fat content. Their vibrant red flesh and striking silver scales in their ocean phase make them easily identifiable and a popular target for anglers during their fall runs.
Sockeye Salmon
Sockeye salmon (*Oncorhynchus nerka*) are unique for their dramatic physical transformation. While in the ocean they are a silvery blue, but upon entering freshwater to spawn, their bodies turn a brilliant red and their heads develop a distinctive green head. Sockeye are the most commercially valuable of the Pacific salmon in some regions due to their firm, orange-red flesh and high oil content. Unlike other species, a significant portion of the Sockeye population is landlocked, living entirely in lakes and never migrating to the sea.
Pink and Chum Salmon
Pink salmon (*Oncorhynchus gorbuscha*) are the most abundant species in the Pacific and the smallest of the group, rarely exceeding 15 pounds. They are easily identified by the large humps that develop on their backs during spawning, leading to their nickname "Humpback" salmon. Chum salmon (*Oncorhynchus keta*), also called Dog salmon, are the most widely distributed species geographically. They have a milder flavor and are often the primary subsistence food for indigenous communities across the North Pacific, valued for their reliability rather than their culinary delicacy.
The Atlantic Salmon
To fully answer how many species of salmon exist, one must look across the Atlantic Ocean. Here, there is a single species, *Salmo salar*, which translates from Latin as "the leaper." Atlantic salmon share the same anadromous lifecycle as their Pacific cousins but belong to a different genus. Historically, they were found in rivers from Connecticut to northern Russia, but populations have declined sharply due to dams, pollution, and overfishing. Conservation efforts are now focused heavily on restoring these historic runs, distinguishing them ecologically and genetically from the *Oncorhynchus* genus.
