Is it a Chinook Salmon or Coho Salmon?

August 11, 2025

Fishing

Coho and Chinook salmon are two commonly caught species in the Siuslaw River in Oregon, each with distinct characteristics and significance to the river’s ecosystem and local fishing practices.

Coho Salmon (Oncorhynchus kisutch)

Identification: Coho salmon, also known as “silver” salmon, can be identified by the distinct banding pattern on their lower jaw, with a dark band outside the base of the teeth, a white or very light band at the base, and another dark band inside. They have sharp, firmly set teeth, and their tail may or may not have round spots in the upper lobe. Occasionally, coho will have spots in both lobes of the tail, and small spots may or may not be present on the back.

Life Cycle and Habitat: Coho salmon spend their early life in freshwater, migrate to the ocean, and return to freshwater to spawn and die. They are known for remaining at sea over the second winter, feeding voraciously before returning to their home streams or neighboring streams to spawn. After spawning, they die, contributing nutrients to support the next generation.

Conservation Efforts: The Siuslaw River, among other rivers on the Oregon coast, is a critical habitat for coho salmon. Efforts to restore salmon populations focus on improving fish habitat in watersheds, addressing factors of decline such as harvest and hatchery effects. The Siuslaw River basin supports some of the largest runs of coho salmon on the Oregon Coast.

Chinook Salmon (Oncorhynchus tshawytscha)

Identification: Chinook salmon, also known as “king” salmon, have a lower jaw that is a uniform dark coloration, sometimes mottled. Unlike coho, bone segments in the fin rays of the tail cannot be felt by lightly running a fingernail along the top of a fin ray. They also have sharp, firmly set teeth, and their tail may have round spots in both the upper and lower lobe. Large wavy spots are usually present on the back.

Size: Chinook salmon are the largest of the salmon species, with fish over 50 pounds being caught on occasion. The average size of an ocean-caught Chinook is 12-15 pounds.

Significance: The Siuslaw River is treasured by anglers for being home to Chinook, steelhead, and coho salmon. It supports a staggering array of fish and wildlife species, making it one of the richest ecosystems in the Coast Range.

Conservation and Fishing Practices

Both species are subject to fishing regulations that require anglers to correctly identify salmon species, as restrictions such as legal lengths and seasons often vary based on the species. Incorrect identification can lead to fines and confiscation of the catch. The Siuslaw River basin’s diverse geography supports a variety of wildlife species and is a cherished fishing destination, with salmon fishing peaking in September and early October.

Conclusion

While both coho and Chinook salmon are vital to the Siuslaw River’s ecosystem and local fishing community, they can be distinguished by physical characteristics such as the pattern on their lower jaw, the presence of bone segments in the fin rays of the tail, and size. Conservation efforts in the Siuslaw River basin aim to protect and improve habitat for these species, contributing to the recovery of threatened Oregon Coast Coho and ensuring the long-term health of the river’s salmon populations.