How to Identify Chinook Salmon

To identify Chinook Salmon (Oncorhynchus tschawytscha), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Ocean-phase Chinook are typically iridescent blue-green on the back, fading to silvery sides and a white belly. They have irregular black spots on the back, dorsal fin, and both lobes of the caudal (tail) fin. Spawning adults undergo dramatic color changes, becoming darker, often olive-brown, reddish, or even black, with males developing a pronounced kype (hooked jaw).

Scale type

cycloid

Mouth position

terminal

Distinctive features

Large size, often exceeding 20 kg (44 lbs), Irregular black spots on the back and both lobes of the caudal fin, Black gum line at the base of the teeth in the lower jaw (distinguishes from other Pacific salmon), Relatively small, adipose fin present, Large, deeply forked caudal fin

Dorsal fin

Single, relatively tall dorsal fin with 10-14 rays, located mid-body. An adipose fin (small, fleshy fin without rays) is present between the dorsal and caudal fins.

Tail fin

Large, deeply forked caudal fin with irregular black spots on both lobes.

Pectoral fin

Paired pectoral fins located just behind the gills, moderately sized.

Distinctive fins

Pelvic fins are abdominal, located beneath the dorsal fin. Anal fin has 13-19 rays.

Identification Tips

1. 1

   Size

   Chinook are generally the largest Pacific salmon, often exceeding 10 kg (22 lbs) and sometimes reaching over 30 kg (66 lbs).

2. 2

   Black Gum Line

   Open the mouth and look at the lower jaw. Chinook Salmon have a distinctive black pigment along the gum line where the teeth are set, which is absent in other Pacific salmon species (except for some rare Coho variants, but Coho lack spots on both tail lobes).

3. 3

   Tail Spots

   Look for irregular black spots on both the upper and lower lobes of the caudal (tail) fin. Other salmon species may have spots on only the upper lobe or no spots at all.

4. 4

   Body Coloration (Ocean Phase)

   Iridescent blue-green back, silvery sides, and a white belly. Spawning coloration is much darker, often olive-brown to reddish.

5. 5

   Pyloric Caeca

   Internally, Chinook have a very high number of pyloric caeca (140-240), which are finger-like projections at the junction of the stomach and intestine. This is a definitive but invasive identification feature.

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