Steelheader's Advisory: Fall Chinook And Coho Salmon Headed For Idaho Waters

LEWISTON - Idaho steelhead anglers are already savvy at fish identification, but with the expected appearance of fall-run chinook and coho salmon in area rivers this fall, anglers must sharpen their skills even more. Some of these fish will have missing adipose fins, similar to hatchery steelhead, but there is no open season for fall chinook and coho salmon, and they must be released immediately. The easiest way to distinguish a chinook salmon from a steelhead is by checking the lower gum line of the jaw. If the lower gum is black, it's a chinook. Using the gum line test, identification can be made quickly without taking the fish out of the water. Another feature that helps differentiate chinook salmon from steelhead is the spotting on the back and tail. The dark spots on the back of a chinook are blotchy and irregular in shape. On a steelhead, the spots are rounded and more uniform. The black spots on the upper part of the tail fin of a chinook are large in comparison to the spots on the tail of a steelhead. Fall Chinook may range in size from 5 to 40 pounds. Coho salmon usually have dark mouths also, but white gums. Probably the easiest distinguishing mark is the tail fin. On a steelhead, black spots are distributed throughout the tail fin. On a coho salmon, spots appear only on the upper lobe of the fin, if at all. A second identifier is the anal fin, located on the underside of the fish in front of the tailfin. On a steelhead, the trailing edge of the anal fin lines up perpendicular to the fish's body, while the trailing edge of a coho's anal fin slants toward the body.