Oncorhynchus keta

Chum salmon have many small scales, a dorsal fin, and an adipose fin (between the dorsal and tail fins). Their fins have no spines. They have 18 to 28 short, stout, smooth gill rakers in their first gill arch. Neither their back nor their tail has distinct large black spots; rather, the upper side of the larger salmon is steel-blue with black speckles. They have silvery sides and a silvery to white belly. The tips of the tail, anal, and pectoral (side) fins are tinged black in males.

Spawning males: A dark olive to black upper side, green sides with vertical red or dusky bars or blotches, and white-tipped anal and pelvic fins.

Spawning females: Similar to spawning males, but less distinctly marked.

Juveniles: Have six to 14 narrow, short parr marks (dark round patches) on each side.

Adults can reach a total length of around 102 cm.

This species has the widest natural range of all the Pacific salmon species. In Asia, the range extends from Korea north to the Arctic Ocean and west along the coast of northern Asia to the Lena River/Laptev Sea. (Consider adding a country to orient readers.) In North America, chum salmon occurred historically from the Sacramento River drainage, California (rarely the San Lorenzo River, Southern California), to northwestern Alaska, and east along the Arctic coast to the Anderson and Mackenzie Rivers, Northwest Territories. The species is now rare or locally extirpated from southern Oregon southward. Immatures are widely distributed over the north Pacific Ocean.

Chum salmon spawn in gravel riffles in rivers and streams of various sizes, but spend most of their lives in the ocean.
 

Chum salmon spend most of their lives (sometimes 2 to 7 years, usually 3 to 5 years) in the ocean. Adults return to spawn in the streams where they hatched. They sometimes swim up to 2,000 km (about 1,2500 miles) upstream in rivers that do not have major barriers in Alaska and Canada, but most spawn in rivers not far from saltwater (usually within 100 km or 62 miles). In many areas, chum salmon enter streams in distinct seasonal runs (e.g., summer and fall). In Washington state, spawning usually occurs in fall, October to December. Adults die about a week after spawning. Depending on the water temperature, eggs hatch within several months and the alevins (newly hatched) feed off their yolk in the gravel environment. Fry (the next stage of development) migrate directly to the sea soon after they emerge, with peak migration in April to May in Washington. Fry spend relatively little time in fresh water.