Atlantic Salmon
  • Side view adult.
  • Side view adult.
  • Side View adult.
  • Top view adult.
  • Bottom view adult.
  • Head-on view adult.
  • Close-up flank.
  • Close-up head.
  • Close-up mouth and snout.
  • Close-up tail.
  • Close-up dorsal fin.
  • Close-up anal fin.
  • Close-up pectoral fins.
  • Close-up felvic fin.
  • View of inside: There are 40-74 pyloric caecae.
  • The tail shows a few spots limited to the base.
  • The flanks show dark spots on light background, some of them X-shaped, no red spots, 109-121 lateral line scales.
  • The head region also shows dark spots on light background, some of them X-shaped, some nearly as large as the pupil.
  • There are 11-12 principal dorsal rays; there are no spots on the dorsal fin.
  • Close-up of underside of lower jaw: There are usually 11-12 branchiostegal rays on each side.
  • Close-up of inside of mouth: Vomerine teeth on the middle of the roof of the mouth are poorly developed or absent.
  • The inside of mouth is white with little pigment.
  • Close-up of tail region: Note that the adipose fin is not edged in red.
  • There are 7-12, usually 9-11, principal anal rays. The image shows a breeding fish recognizable by its very dark fin.
  • Males develop a very dark color and a hooked lower jaw.
  • Females develop a very dark color, but no hooked lower jaw.
  • Females develop a very dark color, but no hooked lower jaw.
  • Males develop a very dark color and a hooked lower jaw.
  • Side view of young-of-year showing parr marks.
  • Side view of young-of-year showing parr marks.
DescriptionSimilar Species
Family
Trouts (Salmonidae)
Body
Mouth and snout: The Atlantic salmon has a large, slightly oblique terminal mouth with numerous small to medium-sized teeth on the upper and lower jaws (but few or none on vomer). There are no barbels. Body pattern: There are spots on each side; juveniles also have a thick dark vertical bar (“parr marks”). The background body color is silvery, silver-blue, or light olive, grading to cream on the belly. The spots are mostly dark brown or black with often a few reds; some are round, others irregular ovals, and others “X” shaped, some nearly as large as the pupil of the eye. The Atlantic salmon has 109-121 cycloid lateral line scales. The dorsal and tail fins are tan or olive; dorsal fins and the tail have few or no spots, usually limited to base of tail. Pectoral, pelvic, and anal fins are light olive or tan without spots. The adipose fin is not edged in red or orange. The body shape is fusiform and oval in cross section. In Great Lakes, TL is typically 450-600 mm (18-24 in) with the maximum about 700 mm (28 in).
Fins
Tail, dorsal and other fins: Slightly forked to square tail. Single dorsal fin with no spines and usually 11-12 principal rays. Pelvic fins abdominal with axillary process. Adipose fin present. Anal fin with 7-12 principal rays, usually 9-11.
Distinguishing Characteristics
The Atlantic salmon can be distinguished by its pattern of dark spots on a light background. See also similar species information.
Breeding Adults
Breeding adults: Males develop a hooked lower jaw. The body and fins of both sexes become darker (bronze to dark brown) with pronounced spots prior to spawning and turn black after spawning.
Juveniles
Juveniles gave 8-11 narrow oval vertical bars (“parr marks”) on sides. Spots are relatively scarce and inconspicuous in young-of-year fish. Older juveniles have more adult-like spotting patterns but retain parr marks, which disappear as the fish smolts and leaves the natal stream and moves into the Great Lakes.
Hybrids
None known from Wisconsin.
Compare Similar Species
Spot Characteristics
Salmon, AtlanticUsually few, covering upper sides; black & sometimes red present; nearly as large as pupil of eye; round, irregular ovals, or “X” shaped
Salmon, ChinookModerate to numerous, limited to upper half of sides; black only; much smaller than pupil of eye; round or irregular in shape
Salmon, CohoUsually few, and limited to back and upper sides; black only; much smaller than pupil of eye; round or irregular in shape
Salmon, KokaneeAlmost none, limited to upper back; black only; much smaller than pupil of eye; round to slightly oval in shape
Salmon, PinkModerate in number, covering upper sides; black only; nearly as large as pupil of eye; round or oval in shape
Trout, BrookModerate to numerous; covering sides; cream, light, olive, yellow, red, sometimes with bluish halo; much smaller than pupil of eye; round
Trout, BrownFew to many, covering most of sides; both black and red present; nearly as large as pupil of eye; round or irregular ovals in shape
Trout, LakeMany; covering sides; cream to light olive; much smaller than pupil of eye; irregular shape, much smaller than pupil of eye
Trout, RainbowMany, covering most of sides; black only; much smaller than pupil of eye; round or irregular in shape
Tail Spots
Salmon, AtlanticFew or none, usually limited to base of tail
Salmon, ChinookModerate to numerous and on both lobes
Salmon, CohoFew, limited to top of upper lobe
Salmon, KokaneeNone
Salmon, PinkNumerous and on both lobes, forming lines of elongated oval spots along rays
Trout, BrookFew and lighter
Trout, BrownFew or none, usually limited to base of tail
Trout, LakeNumerous and on both lobes
Trout, RainbowNumerous and on both lobes
Principal Anal Rays
Salmon, Atlantic7-12, usually 9-11
Salmon, Chinook14-19
Salmon, Coho12-17, 1st ray elongated; fin distinctly falcate in YOY
Salmon, Kokanee11-16, usually 13-14
Salmon, Pink13-19
Trout, Brook7-13, usually 9
Trout, Brown8-12, usually 9-11
Trout, Lake8-10
Trout, Rainbow8-12
Lateral Line Scales
Salmon, Atlantic109-121
Salmon, Chinook130-165
Salmon, Coho112-148
Salmon, Kokanee121-140
Salmon, Pink147-205
Trout, Brook210-244
Trout, Brown120-130
Trout, Lake185-210
Trout, Rainbow100-150
Inside of Mouth in Breeders
Salmon, AtlanticWhite
Salmon, ChinookBlack or dark gray
Salmon, CohoBlack or gray; gums white
Salmon, KokaneeDark gray with white mottling
Salmon, PinkTongue and tip of jaw black or gray; gums white
Trout, BrookWhite on the teeth, tongue, and inside of mouth, but black on the gums
Trout, BrownWhite
Trout, LakeWhite
Trout, RainbowWhite
Other Features
Salmon, AtlanticBranchiostegal rays usually 11-12, principal dorsal rays 11-12, adipose fin not edged in red, pyloric caecae 40-74, gill rakers 15-20, vomerine teeth poorly developed, dorsal fin with few or no spots
Salmon, ChinookBranchiostegal rays usually 13-19, principal dorsal rays 10-14, adipose fin not edged in red, pyloric caecae 140-185, gill rakers 16-26, vomerine teeth well developed, dorsal fin spotted
Salmon, CohoBranchiostegal rays usually 11-15, principal dorsal rays 9-12, adipose fin not edged in red, pyloric caecae 45-114, gill rakers 18-25, vomerine teeth well developed, dorsal fin with few or no spots
Salmon, KokaneeBranchiostegal rays usually 13-14, principal dorsal rays 11-13, adipose fin not edged in red, pyloric caecae 50-87, gill rakers 29-43, vomerine teeth well developed, dorsal fin with few or no spots
Salmon, PinkBranchiostegal rays usually 9-15, principal dorsal rays 10-15, adipose fin not edged in red, pyloric caecae 95-224, gill rakers 24-35, vomerine teeth well developed, dorsal fin with few or no spots
Trout, BrookBranchiostegal rays usually 9-13, principal dorsal rays 10-14; adipose fin not edged in red, but dark margin in young; pyloric caecae 23-55; gill rakers 9-12; vomerine teeth well developed; dorsal fin spotted
Trout, BrownBranchiostegal rays usually 10, principal dorsal rays 9-11, adipose fin often edged in red, pyloric caecae 30-60, gill rakers 14-17, vomerine teeth well developed, dorsal fin spotted
Trout, LakeBranchiostegal rays usually 10-14, principal dorsal rays 8-10, adipose fin not edged in red, pyloric caecae 93-208, gill rakers 16-26, vomerine teeth well developed, dorsal fin spotted
Trout, RainbowBranchiostegal rays usually 9-13, principal dorsal rays 10-12, adipose fin not edged in red, pyloric caecae 27-80, gill rakers 16-22, vomerine teeth well developed, dorsal fin heavily spotted
Similarity Index
Salmon, AtlanticN/A
Salmon, ChinookModerately similar
Salmon, CohoModerately similar
Salmon, KokaneeModerately similar
Salmon, PinkModerately similar
Trout, BrookModerately similar
Trout, BrownVery similar
Trout, LakeModerately similar
Trout, RainbowModerately similar
Comments
Salmon, AtlanticNot native; stocked in the past without estabishing a population. Occurs only in the Great Lakes as a rare stray from other states and Ontario.
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