How to Identify Atlantic Salmon

To identify Atlantic Salmon (Salmo salar), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Adults in freshwater (spawning phase) are typically dark brown to bronze with reddish spots, often with a reddish belly in males. Sea-run adults are silvery with a dark back (blue-green to black) and scattered black spots, particularly above the lateral line. Juveniles (parr) have distinct dark vertical bars (parr marks) and red spots along their flanks.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Adipose fin present (a small, fleshy fin between the dorsal and caudal fins)., Large, well-developed scales., Relatively small mouth, extending to or slightly beyond the posterior margin of the eye., Vomerine teeth are present, typically in a single, irregular row., Caudal peduncle is slender.

Dorsal fin

Single dorsal fin, relatively short, with 10-13 soft rays. An adipose fin is present posterior to the dorsal fin.

Tail fin

Moderately forked caudal fin (tail fin).

Pectoral fin

Paired pectoral fins, relatively small.

Distinctive fins

Pelvic fins are abdominal, located beneath the dorsal fin. Anal fin is short with 8-11 soft rays.

Identification Tips

1. 1

   Parr Marks

   Juvenile Atlantic Salmon (parr) have 8-11 distinct, dark, vertical bars (parr marks) along their sides, often with a single red spot between each bar. This distinguishes them from trout parr which typically have more numerous and less distinct parr marks, and often more red spots.

2. 2

   Caudal Peduncle

   The caudal peduncle (the narrow part of the body connecting the main body to the tail fin) of Atlantic Salmon is noticeably slender, especially compared to Pacific salmon species.

3. 3

   Mouth Size

   The mouth of an Atlantic Salmon is relatively small, typically not extending beyond the posterior margin of the eye. This contrasts with many Pacific salmon species where the mouth extends well past the eye.

4. 4

   Spotting Pattern

   Sea-run Atlantic Salmon have relatively few, scattered black spots, primarily above the lateral line. These spots are usually X-shaped or star-shaped. Brown Trout (Salmo trutta) often have more numerous spots, including below the lateral line, and often with a halo effect.

5. 5

   Vomerine Teeth

   Adult Atlantic Salmon possess vomerine teeth (teeth on the roof of the mouth) in a single, irregular row. This differs from Brown Trout which typically have a double or zigzag row of vomerine teeth.

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